Abstract: Described are magnetic recording heads that include an overcoat that includes a titanium oxynitride (TiON) layer.

Abstract: An apparatus according to one embodiment includes a beam and a module coupled to the beam. The module has an array of transducers. A displacement device is positioned between the beam and the module for bending the module, thereby altering a pitch of the transducers. A method according to one embodiment includes applying a control signal to a displacement device positioned between a module having an array of transducers and a beam for bending the module, thereby altering a pitch of the transducers.

Abstract: Disclosed herein are slider designs having improved trailing air flow dams, and data storage devices including such sliders. In some embodiments, a slider comprises a trailing edge and an air-bearing surface (ABS) comprising a trailing edge pad, and a trailing air flow dam coupled to the trailing edge pad, wherein, in an ABS view of the slider, the trailing air flow dam is recessed from and curves away from the trailing edge. In the ABS view, a shape of the trailing air flow dam may comprise two segments. The slider also has a leading edge and may at least one sub-ambient pressure cavity adjacent to the trailing air flow dam and disposed between the trailing air flow dam and the leading edge. A contact point of the trailing air flow dam may be at least 50 microns from a corner of the slider.

Abstract: Described are magnetic recording heads that include an air-bearing surface and that are designed to be useful or potentially useful in two or more different types of fluid atmospheres; also described are related methods of testing the magnetic recording heads and installing the magnetic recording heads in a hard disk drive, as well as hard disk drives that contain a magnetic recording head as described.

Abstract: A piston ring having a hard carbon film formed on at least an external peripheral sliding surface of a piston ring base material, the hard carbon film having an sp2 component ratio within a range of 40% to 80% inclusive as measured by a TEM-EELS spectrum which combines electron energy loss spectroscopy (EELS) with a transmission electron microscope (TEM), a hydrogen content being in a range of 0.1 at. % to 5 at. % inclusive, and an amount of macroparticles appearing on the surface being within a range of 0.1% to 10% inclusive by area ratio. The hard carbon film is formed on a hard carbon foundation film formed under low-speed film-forming conditions on the side of the piston ring base material, and the hard carbon foundation film is formed with an arc current value 80% or less of the arc current value during the formation of the hard carbon film.

Abstract: A slider for a head to read data from or write data to a magnetic media is disclosed. The slider includes an air bearing surface including raised bearing surface(s) elevated above recessed bearing surface(s) to pressurize air flow along the air bearing surface to provide a fly height for the slider above the media. The raised bearing surfaces are formed along one or more raised substrate structures etched from a substrate body. The slider includes one or more insets inset into the one or more raised substrate structures formed of an inset material having a different coefficient of expansion than a substrate material of the slider to compensate for temperature and/or humidity changes.

Abstract: Reducing slider bounce within a hard disk drive. A force is received at a first material while the first material is in contact with a disk of a hard disk drive; the first material comprising a portion that is flexible in a first direction and is substantially non-flexible in a second direction. The first direction is a direction that is normal to the disk and the second direction is a direction that is parallel to a surface of the disk. The force is substantially absorbed by the portion that is flexible to reduce the force associated with interaction between the first material and the disk, thereby reducing slider bounce within the hard disk drive.

Abstract: A magnetic data storage drive that includes a self-assembled monolayer having a magnetic function. The drive comprises a magnetic data storage medium having a magnetic surface, a slider having a working surface, the slider positioned and configured to detect magnetic fields from the magnetic surface of the medium, and a self-assembled monolayer between the magnetic surface and the working surface, the self-assembled monolayer having a magnetic function to reduce dispersion of magnetic fields from the magnetic surface of the medium to the working surface of the slider.

Abstract: A magnetic-recording head with touch-down detector incorporating a carbon nano-tube (CNT). The magnetic-recording head includes a write element, a read element and a touch-down detector. The write element is configured to write data to a magnetic-recording disk. The read element is configured to read data from the magnetic-recording disk. The touch-down detector includes a thermal sensor, and a CNT portion. The thermal sensor is configured to convert heat to a voltage signal. The CNT portion is configured to touch down on the magnetic-recording disk. The CNT portion is also coupled to the thermal sensor, and is configured to transfer heat generated by contact between the CNT portion and the magnetic-recording disk to the thermal sensor. A hard-disk drive (HDD) including the magnetic-recording head with touch-down detector incorporating a CNT, and a method for detecting contact between the magnetic-recording head and a recording surface of a magnetic-recording disk are also provided.

Abstract: A magnetic slider for magnetic data recording constructed by a process that allows for careful control of seed layer and overcoat thickness. The slider is treated by a process that result in surface pits and scratches. A refill layer is used to fill in the pits and scratches, the refill layer being constructed of a material that does not include Si or carbon. An angled ion beam etching can be used to remove portions of the refill layer that extend outside of the pits and scratches. Then, a seed layer comprising Si and a protective layer comprising C are deposited over the surface. Because the refill layer does not contain either of Si or C, the thickness of the seed layer and carbon overcoat can be acurately measured and controlled, without the refill layer being mistaken for seed or overcoat material.

Abstract: A head-slider. The head-slider includes a slider, and a thin-film magnetic-recording head. The thin-film magnetic-recording head includes: a read element; a write element; a non-magnetic insulating protective layer disposed around both read and write elements; a resist disposed at a position further away from an air-bearing surface than the read element; and, a hard-material member including a material selected from the group consisting of silicon carbide and tungsten, which is disposed at a position further away from the air-bearing surface than the read element and the write element. Both an end of the resist and an end of the hard-material member overlap the write element when viewed in a stacking direction. A ratio of a distance from the air-bearing surface to a deepest end of the hard-material member to a distance from the air-bearing surface to a deepest end of the resist is at least 0.9.

Abstract: A magnetic slider for magnetic data recording constructed by a process that allows for careful control of seed layer and overcoat thickness. The slider is treated by a process that result in surface pits and scratches. A refill layer is used to fill in the pits and scratches, the refill layer being constructed of a material that does not include Si or carbon. An angled ion beam etching can be used to remove portions of the refill layer that extend outside of the pits and scratches. Then, a seed layer comprising Si and a protective layer comprising C are deposited over the surface. Because the refill layer does not contain either of Si or C, the thickness of the seed layer and carbon overcoat can be accurately measured and controlled, without the refill layer being mistaken for seed or overcoat material.

Abstract: A magnetic head that includes: a slider having a leading edge and a trailing edge; and a transducer, the transducer formed on the trailing edge of the slider and the transducer including: a substrate; a basecoat positioned adjacent the substrate, wherein the basecoat includes a material having a Young's modulus that is less than that of alumina and a coefficient of thermal expansion that is less than that of alumina; a reader; a writer; a heater; and an overcoat encasing at least a portion of the transducer, wherein the overcoat includes a material having a Young's modulus that is less than that of alumina and a coefficient of thermal expansion that is less than that of alumina.

Abstract: A magnetic device that includes a write pole having a write pole tip; a read pole having a read pole tip; an optical near field transducer; and a contact pad. The contact pad includes Ni100-aXa, wherein X is chosen from Ru, Re, Zr, Cr, and Cu; and a is the atomic percent of the element X, and can range from about 20 to about 90. The optical near field transducer is positioned between the read pole and the write pole and the contact pad is positioned adjacent the write pole opposite the optical near field transducer.

Abstract: A slider includes a slider body having a first side and edges defined adjacent to the first side, at least two separate insulators each adjacent to the first side of the slider body and supported by the slider body, and a conductive trace adjacent to each of the at least two separate insulators and opposite the first side of the slider body. The at least two separate insulators each are in physical contact with the slider body along the first side of the slider body such that the at least two separate insulators are physically attached to the slider body to electrically insulate each conductive trace from the slider body.

Abstract: A magnetic disk device includes a magnetic disk and a magnetic head having a magnetic head slider flying by an action of air during rotation of the magnetic disk, wherein an inflow of air from a direction of a leading side face of the magnetic head slider forming an air bearing film effect at an air bearing surface face of the magnetic head slider which faces the magnetic disk, and the air flows out from a trailing side face of the magnetic head slider. The magnetic head slider has a wettability, in at least a part of an outer region defined on the trailing side face and adjoining other faces including the air bearing surface face of the magnetic head slider, which is lower than a wettability of at least one other region present at the trailing side face.

Abstract: A substrate for a magnetic read/write head is disclosed. The substrate can reduce detachment of crystal grains when the substrate is machined. The substrate may be machined when the substrate is cut into strips or a flow path surface recess is formed to produce the magnetic read/write head. The reduced detachment of crystal grains makes the magnetic read/write head more resilient to chipping, which allows the magnetic read/write head to have a lower and more stable flying height that increases recording density.

Abstract: A magnetic device that includes a write pole having a write pole tip; a read pole having a read pole tip; an optical near field transducer; and a contact pad. The contact pad includes Ni100-aXa, wherein X is chosen from Ru, Re, Zr, Cr, and Cu; and a is the atomic percent of the element X, and can range from about 20 to about 90. The optical near field transducer is positioned between the read pole and the write pole and the contact pad is positioned adjacent the write pole opposite the optical near field transducer.

Abstract: A slider is formed of a two-phase material having a first component and a second component that is harder than the first component. A media-facing surface is formed on two-phase material, with a leading edge extending transversely from the media-facing surface. The second component is selectively removed from the two-phase material in a contact region located along at least one of the leading edge and the media-facing surface, such that a hardness of the slider is reduced in the contact region.

Abstract: A magnetic head slider according to the present invention comprises: a slider body including either a write head element or a read head element or both the write head element and the read head element; a seed layer provided on an air bearing surface of the slider body, the seed layer covering either the write head element or the read head element or both the write head element and the read head element, the seed layer having a film thickness that is less than 1 nm; and a protective film formed of diamond-like carbon, the protective film covering the seed layer. The seed layer is mainly formed of silicon and contains a 6A group element in a proportion of 2 atomic % or more and 30 atomic % or less.

Abstract: A slider resistant to lubricant accumulation. The slider resistant to lubricant accumulation includes a positive-air-pressure portion of the slider configured to levitate the slider above a magnetic-recording disk and a negative-air-pressure portion of the slider configured to bring the slider into proximity with the magnetic-recording disk at a fly height sufficient for writing data to and reading data from the magnetic-recording disk. The slider resistant to lubricant accumulation also includes a lubricant-accumulation barrier disposed in proximity to a trailing edge of the slider. The lubricant-accumulation barrier is configured to reduce lubricant accumulation on the slider. The lubricant-accumulation barrier also includes a plurality of lubricant-accumulation-barrier portions disposed at a plurality of respective depths below an outer-most surface of a disk-facing side of the slider.

Abstract: A ceramic sintered body contains Al2O3 crystal grains, internal TiC crystal grains existing in the Al2O3 crystal grains and external TiC crystal grains other than the internal TiC crystal grains. The Al2O3 crystal grains and the external TiC crystal grains retain stress caused by the difference in thermal expansion coefficient remaining after sintering, so that the Al2O3 crystal grains and the external TiC crystal grains pull each other in the interface therebetween. As a result, when the ceramic sintered body is machined, micro-cracks generated in the interface can easily grow due to the residual stress in addition to the shearing force caused by the machining operation, so that machinability is improved.

Abstract: A slider resistant to lubricant accumulation. The slider resistant to lubricant accumulation includes a positive-air-pressure portion of the slider configured to levitate the slider above a magnetic-recording disk and a negative-air-pressure portion of the slider configured to bring the slider into proximity with the magnetic-recording disk at a fly height sufficient for writing data to and reading data from the magnetic-recording disk. The slider resistant to lubricant accumulation also includes a lubricant-accumulation barrier disposed in proximity to a trailing edge of the slider. The lubricant-accumulation barrier is configured to reduce lubricant accumulation on the slider.

Abstract: A head slider includes a medium opposing surface configured to oppose a recording surface of a magnetic recording medium, a head element provided on the medium opposing surface, and an outlet end surface provided on a downstream side of the head element in a direction in which the magnetic recording medium moves relative to the head element, and extending substantially in a perpendicular direction from the medium opposing surface. The outlet end surface has a surface free energy greater than a surface free energy of the medium opposing surface.

Abstract: A thin-film magnetic head substrate according to the present invention includes: a ceramic base with a principal surface; and an undercoat film, which covers the principal surface of the ceramic base. An electrical/magnetic transducer is provided on the undercoat film. The substrate further includes an intermediate layer between the principal surface of the ceramic base and the undercoat film. The intermediate layer is made of a material other than an aluminum oxide and has been patterned so as to make a portion of the principal surface of the ceramic base contact with the undercoat film.

Abstract: An apparatus includes a slider body having a leading edge and an opposite trailing edge, as well as a top face and a bottom face each extending between the leading edge and the trailing edge. The slider body further includes a plurality of protrusions extending from the bottom face, a first recess defined on one of the protrusions, and a sacrificial layer deposited on the slider body in the recess. A bottom surface of the sacrificial layer extends at least as far from the bottom face as bottom surfaces of the plurality of protrusions. In another aspect, a first blocking feature is located at a first uptrack edge on an air bearing surface of a slider, with the first blocking feature being substantially continuous along the first uptrack edge and protruding outwardly from the air bearing surface to reduce particle interaction with the air bearing surface.

Abstract: Recording heads for a data storage system include a first side having at least a portion of a metal component. A carbon overcoat is on the first side and covers the at least a portion of a metal component. A corrosion inhibitor is incorporated in the carbon overcoat. The corrosion inhibitor is illustratively located between the carbon overcoat and the at least a portion of a metal component, on top of the carbon overcoat, or within the carbon overcoat. In an embodiment, the carbon overcoat includes diamond-like carbon.

Abstract: A slider for magnetic data recording having a semiconductor based magnetoresistive sensor such as a Lorentz magnetoresistive sensor formed on an air bearing surface of the slider body. The slider is constructed of Si, which advantageously provides a needed physical robustness as well being compatible with the construction of a semiconductor based sensor thereon. A series of transition layers are provided between the surface of the Si slider body and the semiconductor based magnetoresistive sensor in order to provide a necessary grain structure for proper functioning of the sensor. The series of transition layers can be constructed of layers of SiGe each having a unique concentration of Ge.

Abstract: A head slider that can furnish excellent head flying stability and a magnetic recording device having excellent head flying stability are provided. For the head slider, the protective layer is composed of two layers, that is, a lower layer and an upper layer thereon; the ionization potential of the lower layer is made to be smaller than that of the upper layer; and the surface free energy of the upper layer is made to be 45 mN/m or less.

Abstract: A protective bilayer on a magnetic read/write head or magnetic disk is formed as an adhesion enhancing and corrosion resistant underlayer and a protective diamond-like carbon (DLC) overlayer. The underlayer is a transition metal oxynitride, having the general formula MeOxNy, where Me represents a single element or an alloy of the following transition metal elements: Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W, here x can be within the range between 0 and 3 and y is in the range between approximately 0 and 2. Adjusting the values of x and y contributes to such qualities of the protective bilayer as stress compensation, chemical and mechanical stability and low electrical conductivity. Methods of forming the adhesion layer, include reactive ion sputtering, plasma assisted chemical vapor deposition, pulsed laser deposition and plasma immersion ion implantation.

Abstract: A method is disclosed for producing sliders with protective contacts features the fabrication of which is initiated at the wafer level. Recesses are formed in the wafer, a protective material is provided in the recesses, and the wafer is sliced along the recesses and diced into sliders, such that the protective material forms corners of the sliders. The protective material may be disposed such that it has a low elastic modulus at the corners, and a higher elastic modulus at a displacement from the corners which is still lower than the elastic modulus of the slider body, thereby providing superior protection for potential contacts between the slider and an adjacent media surface.

Abstract: A transducer carrying structure includes a first portion carrying the transducer, a second portion spaced from the transducer, and a spacing control actuation system operable to adjust a position of the first portion of the transducer carrying structure. An overcoat is provided on a surface of the transducer carrying structure. The overcoat has a first thickness in the first region of the transducer carrying structure and a second thickness in the second region of the transducer carrying structure, the second thickness being greater than the first thickness. This configuration provides increased wear robustness to the transducer carrying structure without causing the transducer to be excessively spaced from a medium during operation of the transducer.

Abstract: A head-slider. The head-slider includes a slider, and a thin-film magnetic-recording head. The thin-film magnetic-recording head includes: a read element; a write element; a non-magnetic insulating protective layer disposed around both read and write elements; a resist disposed at a position further away from an air-bearing surface than the read element; and, a hard-material member including a material selected from the group consisting of silicon carbide and tungsten, which is disposed at a position further away from the air-bearing surface than the read element and the write element. Both an end of the resist and an end of the hard-material member overlap the write element when viewed in a stacking direction. A ratio of a distance from the air-bearing surface to a deepest end of the hard-material member to a distance from the air-bearing surface to a deepest end of the resist is at least 0.9.

Abstract: A slider for an information storage system. The slider comprising a single overcoat layer, wherein the layer is deposited onto an ABS of the slider by a filtered cathodic arc process, the layer having a Si/C ratio less than about 10% and a thickness of less than about 15 ?.

Abstract: A slider is formed of a two-phase material having a first component and a second component that is harder than the first component. A media-facing surface is formed on two-phase material, with a leading edge extending transversely from the media-facing surface. The second component is selectively removed from the two-phase material in a contact region located along at least one of the leading edge and the media-facing surface, such that a hardness of the slider is reduced in the contact region.

Abstract: A substrate for a magnetic read/write head is disclosed. The substrate can reduce detachment of crystal grains when unexpected vibrations or impacts are applied. The substrate may be machined when the substrate is cut into strips or a flow path surface recess is formed to produce the magnetic read/write head. The reduced detachment of crystal grains makes the magnetic read/write head more resilient to chipping, which allows the magnetic read/write head to have good performance in read/write.

Abstract: A magnetic head slider according to the present invention comprises: a slider body including either a write head element or a read head element or both the write head element and the read head element; a seed layer provided on an air bearing surface of the slider body, the seed layer covering either the write head element or the read head element or both the write head element and the read head element, the seed layer having a film thickness that is less than 1 nm; and a protective film formed of diamond-like carbon, the protective film covering the seed layer. The seed layer is mainly formed of silicon and contains a 6A group element in a proportion of 2 atomic fractions or more and 30 atomic fractions or less.

Abstract: In one embodiment of the present invention, a method of producing a magnetic head slider comprises the steps of forming, on the air bearing surface of the slider, an air bearing surface overcoat, removing the surface region from a hard amorphous carbon film by the irradiation with an ion beam which is tilted with respect to a normal to the air bearing surface, and forming a rail in the air bearing surface on which the air bearing surface overcoat has been formed. A high density and covering performance are obtained when the angle of irradiating the ion beam is not smaller than about 60 degrees from a normal to the air bearing surface of the magnetic head slider and when the acceleration voltage for the ion beam is not higher than about 300 V in the step of removing part of the air bearing surface overcoat.

Abstract: A method for forming a protective bilayer on a magnetic read/write head or magnetic disk. The bilayer is formed as an adhesion enhancing underlayer and a protective diamond-like carbon (DLC) overlayer. The underlayer is formed of an aluminum or alloyed aluminum oxynitride, having the general formula AlOxNy or MezAlOxNy where Mez symbolizes Tiz, Siz or Crz and where x, y and z can be varied within the formation process. By adjusting the values of x and y the adhesion underlayer contributes to such qualities of the protective bilayer as stress compensation, chemical and mechanical stability and low electrical conductivity. Various methods of forming the underlayer are provided, including reactive ion sputtering, plasma assisted chemical vapor deposition, pulsed laser deposition and plasma immersion ion implantation.

Abstract: A system and method for measuring and neutralizing the electrical charge at the interface of a magnetic head and a magnetic storage medium, such as a disk, is disclosed. A surface treatment material is applied to the magnetic head. The surface treatment material matches the medium surface material on the surface of the magnetic storage medium. The surface treatment material on the magnetic read/write head may be a fluorinated carbon, such as a Fomblin Z-derivative, perfluoro alkyl trichlorosilane, a FC-722, or a fluorinated polymer. The surface treatment material can be applied to the magnetic head by a vapor deposition process or by a liquid immersion process. The charge on the head-disk interface can be measured by applying varying external charges to the head while reading a signal previously written to the disk.

Abstract: A head slider in a magnetic disk drive wherein provisions are made to facilitate the evaporation of lubricant adhering to the slider and thereby substantially reduce the chance of the fly height of the slider becoming unstable due to a lubricant drop. A head element, a heat generating element, and a multilayered heat conducting structure formed from multiple layers stacked along a longitudinal direction of the slider, with at least one layer extending up to portions near both lateral sides of the slider, are embedded into a nonmagnetic insulating layer formed in an air exit end portion of the slider. The heat generated by the heat generating element is efficiently conducted throughout the nonmagnetic insulating layer to heat the entire structure of the nonmagnetic insulating layer. As a result, the lubricant adhering to any portion of the nonmagnetic insulating layer is efficiently heated, causing the lubricant to evaporate or flow.

Abstract: A method of manufacturing a head suspension assembly for mounting a head slider on a suspension includes an irradiating light step, acquiring position information step and head slider mounting step. The irradiating light step is the step of irradiating light on a protective film and a marker at an incidence angle ?. The acquiring position information step is the step of acquiring position information of the marker by measuring reflected light from the protective film and that of the marker. The head slider mounting step is the step of mounting the head slider at a predetermined position of the suspension by using the difference of the intensity of reflected light from the protective film and that of the marker.

Abstract: Slider including at least one pad including shape memory alloy layer with titanium oxide contact layer. When slider contacts disk surface, pad(s) undergoes solid-to-solid phase change from the first to second phase, absorbing energy and possibly deforming. When contact is removed, the pad recovers its shape as shape metal alloy undergoes a reverse solid-to-solid phase change. A shape memory alloy of elements refers to any molecular or crystalline combination which is a solid possessing the shape memory property of at least two solid phases in the operating and storage conditions of a hard disk drive. A head gimbal assembly including the slider, head stack assembly including at least one head gimbal assembly, and the hard disk drive including the head stack assembly. Manufacturing methods for the slider, the head gimbal assembly, the head stack assembly, and the hard disk drive, as well as the products of these manufacturing processes.

Abstract: In a magnetic disk device, cost reduction is designed by improving productivity, and increase in recording density and increase in capacity of the device or size reduction are designed with reliability being ensured. In one embodiment, a magnetic disk device has a magnetic disk arranged rotatably, a magnetic head slider arranged in a manner of facing a surface of the magnetic disk, and a driving device for moving the magnetic head slider in a radial direction of the surface of the magnetic disk. The magnetic head slider has a silicon slider-substrate-portion and a thin-film head portion which is formed on the slider substrate portion using a thin-film process and forms an air-bearing surface along with the slider substrate portion.

Abstract: The magnetic head slider material of the present invention is a magnetic head slider material made of a sintered body containing alumina, titanium carbide, and carbon; wherein a titanium carbide crystal grain has an average crystal grain size greater than that of an alumina crystal grain in the sintered body.

Abstract: A magnetic head slider disposed opposite to a surface of a magnetic disk, includes a slider main body, a magnetic head element that reads and reproduces data from the magnetic disk, and a vibration absorbing unit that absorbs vibrations generated due to contact between any portion of the slider main body and the surface of the magnetic disk, and that is provided on the slider main body at a predetermined position.

Abstract: A system and method for measuring and neutralizing the electrical charge at the interface of a magnetic head and a magnetic storage medium, such as a disk, is disclosed. A surface treatment material is applied to the magnetic head. The surface treatment material matches the medium surface material on the surface of the magnetic storage medium. The surface treatment material on the magnetic read/write head may be a fluorinated carbon, such as a Fomblin Z-derivative, perfluoro alkyl trichlorosilane, a FC-722, or a fluorinated polymer. The surface treatment material can be applied to the magnetic head by a vapor deposition process or by a liquid immersion process. The charge on the head-disk interface can be measured by applying varying external charges to the head while reading a signal previously written to the disk.

Abstract: A method for forming a planarized surface for at least one bar of sliders for utilization in a hard disk drive is disclosed. In general, at least one bar of sliders is placed on an adhesive layer. A single thermoplastic layer is then provided above the at least one bar of sliders. The single thermoplastic layer is then heated to a softening temperature such that the single thermoplastic layer will flow between the at least one bar of sliders. The single thermoplastic layer is then cooled to form a planarized surface of both said single thermoplastic layer and said at least one bar of sliders at said adhesive layer.

Abstract: The magnetic head slider material of the present invention is constituted by a sintered body containing 100 parts by weight of alumina, 20 to 120 parts by weight of titanium carbide, and 0.2 to 9 parts by weight of carbon.

Abstract: A magnetic recording medium and head slider that can furnish excellent head flying stability, a magnetic recording device having excellent head flying stability, and a method for manufacturing, in a short time, a magnetic recording medium and head slider that can furnish such excellent head flying stability, are provided. For both of the magnetic recording medium and head slider, the protective layers are each composed of two layers, that is, a lower layer and an upper layer thereon; the ionization potential of the lower layer is made to be smaller than that of the upper layer; and the surface free energy of the upper layer is made to be 45 mN/m or less.