Abstract: Disclosed are a fast, highly-integrated and highly-reliable magnetoresistive random access memory (MRAM) and a semiconductor device which uses the MRAM. The semiconductor device performs the read-out operation of the MRAM using memory cells for storing information by using a change in magnetoresistance of a magnetic tunnel junction (MTJ) element with a high S/N ratio. Each memory cell includes an MTJ element and a bipolar transistor. The read-out operation is carried out by selecting a word line, amplifying a current flowing in the MTJ element of a target memory cell by the bipolar transistor and outputting the-amplified current to an associated read data line.

Abstract: A magnetic head at high sensitivity and with enhanced output having a magnetoresistive element of high output and optimal for use in CPP-GMR, the magnetoresistive element comprising a pinned layer 606 containing a half-metal, a free layer 608 formed on one main surface of the pinned layer 606 a spacer 607 formed between the pinned layer 606 and the free layer 608, an anti-ferromagnetic layer 603 formed on the main surface of the pinned layer 606, a soft magnetic layer 604 formed between the pinned layer 606 and the anti-ferromagnetic layer 606, and a noble-metallic layer 605 formed between the pinned layer 606 and the soft magnetic layer.

Abstract: An optical head including a semiconductor laser source, a condenser lens, a photodiode for detecting a laser light emitter from said semiconductor laser source, and an optical coupler unit for collecting the laser light to the photodiode. A chromatic aberration W of condenser lens is satisfied by an expression W(h, NA)={(NA)3&Dgr;&lgr;/4&lgr;}h, where h is a height of incident light from an optical axis on a hologram, NA is a numerical aperture, &Dgr;&lgr; is a wavelength fluctuation, and a &lgr; is a wavelength at recording. The height h is determined so that the chromatic aberration W becomes equal to or less than &lgr;/4.

Abstract: Disclosed are a fast, highly-integrated and highly-reliable magnetoresistive random access memory (MRAM) and a semiconductor device which uses the MRAM. The semiconductor device performs the read-out operation of the MRAM using memory cells for storing information by using a change in magnetoresistance of a magnetic tunnel junction (MTJ) element with a high S/N ratio. Each memory cell includes an MTJ element and a bipolar transistor. The read-out operation is carried out by selecting a word line, amplifying a current flowing in the MTJ element of a target memory cell by the bipolar transistor and outputting the amplified current to an associated read data line.

Abstract: Disclosed are a fast, highly-integrated and highly-reliable magnetoresistive random access memory (MRAM) and a semiconductor device which uses the MRAM. The semiconductor device performs the read-out operation of the MRAM using memory cells for storing information by using a change in magnetoresistance of a magnetic tunnel junction (MTJ) element with a high S/N ratio. Each memory cell includes an MTJ element and a bipolar transistor. The read-out operation is carried out by selecting a word line, amplifying a current flowing in the MTJ element of a target memory cell by the bipolar transistor and outputting the amplified current to an associated read data line.

Abstract: An optical head including a semiconductor laser source, a condenser lens, a photodiode for detecting a laser light emitter from said semiconductor laser source, and an optical coupler means for collecting the laser light to the photodiode. A chromatic aberration W of condenser lens is satisfied by an expression W(h,NA)={(NA)3&Dgr;&lgr;/4&lgr;}h, where h is a height of incident light from an optical axis on a hologram, NA is a numerical aperture, &Dgr;&lgr; is a wavelength fluctuation, and a &lgr; is a wavelength at recording. The height h is determined so that the chromatic aberration W becomes equal to or less than &lgr;/4.

Abstract: A magnetoresistive head which has a high low resistance and a high MR ratio at room temperature and a S/N ratio that does not decrease sharply upon application of a bias voltage. The magnetoresistive head comprises a soft magnetic free layer, a non-magnetic insulating layer, and a ferromagnetic pinned layer. The ferromagnetic pinned layer may have a spin valve layer whose magnetization is fixed with respect to the magnetic field to be detected, and the soft magnetic free layer permits its magnetization to rotate in response to an external magnetic field, thereby changing the relative angle with the magnetization of said ferromagnetic pinned layer and producing the magnetoresistive effect. The absolute value of the magnetoresistive effect has a peak at a temperature in the range from about 0° C. to 60° C. and for a bias voltage Vs (applied across said ferromagnetic pinned layer and said soft magnetic free layer) in the range from +0.2 to +0.8 V and from −0.8 to −0.2 V.

Abstract: A recording disk has a surface provided with guide grooves for controlling the position of a recording head, and recording bits formed in the guide grooves for high-density recording. The recording bits have the shape of a tadpole in a plane. The width Ws of the recording bits is greater than the width Wg of the guide grooves. An AFM probe serving as a recording head travels along the guide grooves without running off the guide grooves. When a tip part of the AFM probe coincides with the recording bit, the tip part drops deep into the guide groove, whereby the recording bit is detected.

Abstract: There are provided a magnetic reproducing head and a magnetic recording head, which are easy to manufacture and suited for recording and reproducing by means of magnetic recording medium of narrow track size. The magnetic reproducing head is constituted by a GMR or TMR magnetic sensor, and a flux guide for introducing a magnetic flux into the magnetic sensor, wherein at least a portion of the flux guide is constituted by a material which is capable of permitting the magnetic flux to pass therethrough at a temperature of not lower than a predetermined temperature Tp, but not permitting the magnetic flux to pass therethrough at a temperature of lower than Tp.

Abstract: There are provided a magnetic reproducing head and a magnetic recording head, which are easy to manufacture and suited for recording and reproducing by means of magnetic recording medium of narrow track size. The magnetic reproducing head is constituted by a GMR or TMR magnetic sensor, and a flux guide for introducing a magnetic flux into the magnetic sensor, wherein at least a portion of the flux guide is constituted by a material which is capable of permitting the magnetic flux to pass therethrough at a temperature of not lower than a predetermined temperature Tp, but not permitting the magnetic flux to pass therethrough at a temperature of lower than Tp.

Abstract: A recording disk has a surface provided with guide grooves for controlling the position of a recording head, and recording bits formed in the guide grooves for high-density recording. The recording bits have the shape of a tadpole in a plane. The width Ws of the recording bits is greater than the width Wg of the guide grooves. An AFM probe serving as a recording head travels along the guide grooves without running off the guide grooves. When a tip part of the AFM probe coincides with the recording bit, the tip part drops deep into the guide groove, whereby the recording bit is detected.

Abstract: A pad for controlling the state of contact or flying of a slider with or to an information-recording medium and a probe for exciting near-field light having a small spot size are mounted on the slider and the pad is near to the probe. Semiconductor laser light focused by an objective lens is converted into near-field light having a small spot size near the top of the probe for exciting near-field light. The slider travels at a height of several tens nm to a recording medium substrate and information is recorded or read out on or from the information-recording medium formed on the recording medium substrate.

Abstract: The optical head is arranged such that a semiconductor laser and a photodetector are formed via a buffer layer on the same substrate; and an opening portion is formed in the substrate under the semiconductor laser and the photodetector. This optical head is further arranged by that the opening portion is filled with a first transparent layer; a diffraction grating is formed on a lower surface of the first transparent layer; a second transparent layer is stacked on a lower surface of the first transparent layer; and a condenser lens is formed on a lower surface of the transparent layer.

Abstract: The optical head is arranged such that a semiconductor laser and a photodetector are formed via a buffer layer on the same substrate; and an opening portion is formed in the substrate under the semiconductor laser and the photodetector. This optical head is further arranged by that the opening portion is filled with a first transparent layer; a diffraction grating is formed on a lower surface of the first transparent layer; a second transparent layer is stacked on a lower surface of the first transparent layer; and a condenser lens is formed on a lower surface of the transparent layer.

Abstract: The optical head is arranged such that a semiconductor laser and a photodetector are formed via a buffer layer on the same substrate; and an opening portion is formed in the substrate under the semiconductor laser and the photodetector. This optical head is further arranged by that the opening portion is filled with a first transparent layer; a diffraction grating is formed on a lower surface of the first transparent layer; a second transparent layer is stacked on a lower surface of the first transparent layer; and a condenser lens is formed on a lower surface of the transparent layer.

Abstract: The present invention provides an optical recording device which is of ultra-high density and is small in size. It comprises a subminiature optical head comprising in turn a semiconductor laser, a photodetector, grating lenses, a cover layer, and a floating slider on which the optical head is mounted. This configuration can provide an optical recording device which is of ultra-high recording density and is subminiature.

Abstract: A multilayer optical information medium provided with structure in which first and second substrates respectively provided with two to four layers of planar information areas are respectively arranged outside wherein the thickness of the above-described first and second substrates is set in the range of 0.52 to 0.65 mm. The above-described planar information area consists of embossed pits provided, for example on the surface of respective substrates or on the surface of a layer formed by transparent material and a semi-reflective layer provided on the embossed pits. A planar information area arranged in the farthest position from respective substrates is provided with a reflective layer in place of the above-described semi-reflective layer. The planar information area arranged in the farthest position from respective substrates may be constituted by a recording layer and a reflective layer provided on the recording layer.

Abstract: There is disclosed a harmonic modulation device of waveguide type including a semiconductor laser, a waveguide for generating a nonlinear optical harmonic of the semiconductor laser by keeping phase matching, means for leading an optical beam of the semiconductor laser to the waveguide, electrodes disposed on the waveguide, and means for modulating a refractive index of the waveguide electro-optically to modulate a phase matching condition and thereby modulate an intensity of the harmonic.

Abstract: An optical information recording/reproducing method for recording and reproducing information using an evanescent light beam includes the steps of installing an optical head near an optical information recording medium, the optical head having a semiconductor laser, a photodetector for detecting a laser beam emitted from a first end surface of the semiconductor laser, and a device for generating evanescent light from the laser beam emitted from a second end surface of the semiconductor laser; injecting a current into the laser to produce a laser beam; generating an evanescent light by the laser beam in the evanescent light generating device; and interacting the evanescent light with the recording medium to record information on or reproduce information from the recording medium.

Abstract: The optical head is arranged such that a semiconductor laser and a photodetector are formed via a buffer layer on the same substrate; and an opening portion is formed in the substrate under the semiconductor laser and the photodetector. This optical head is further arranged by that the opening portion is filled with a first transparent layer; a diffraction grating is formed on a lower surface of the first transparent layer; a second transparent layer is stacked on a lower surface of the first transparent layer; and a condenser lens is formed on a lower surface of the transparent layer.