Abstract: A buffer layer can be used to smooth the surface roughness of a galvanic contact layer (e.g., of niobium) in an electronic device, the buffer layer being made of a stack of at least four (e.g., six) layers of a face-centered cubic (FCC) crystal structure material, such as copper, the at least four FCC material layers alternating with at least three layers of a body-centered cubic (BCC) crystal structure material, such as niobium, wherein each of the FCC material layers and BCC material layers is between about five and about ten angstroms thick. The buffer layer can provide the smoothing while still maintaining desirable transport properties of a device in which the buffer layer is used, such as a magnetic Josephson junction, and magnetics of an overlying magnetic layer in the device, thereby permitting for improved magnetic Josephson junctions (MJJs) and thus improved superconducting memory arrays and other devices.

Abstract: A hysteretic magnetic Josephson junction (HMJJ) device is provided that comprises a non-magnetic spacer disposed between a first ferromagnetic layer and a second ferromagnetic layer, a first ferrimagnetic layer having a first side disposed on a side of the first ferromagnetic layer opposite the non-magnetic spacer, and a second ferrimagnetic layer having a first side disposed on a side of the second ferromagnetic layer opposite the non-magnetic spacer. The first ferrimagnetic layer and the second ferrimagnetic layer are formed from a composition that provides orthogonally magnetic responses relative to the magnetic responses of the first ferromagnetic layer and the second ferromagnetic layer. The HMJJ further comprises a first superconducting material layer having a first side disposed on a second side of the first ferromagnetic layer and a second superconducting material layer having a first side disposed on a second side of the second ferromagnetic layer.

Abstract: A hysteretic magnetic Josephson junction (HMJJ) device is provided that comprises a non-magnetic spacer disposed between a first ferromagnetic layer and a second ferromagnetic layer, a first ferrimagnetic layer having a first side disposed on a side of the first ferromagnetic layer opposite the non-magnetic spacer, and a second ferrimagnetic layer having a first side disposed on a side of the second ferromagnetic layer opposite the non-magnetic spacer. The first ferrimagnetic layer and the second ferrimagnetic layer are formed from a composition that provides orthogonally magnetic responses relative to the magnetic responses of the first ferromagnetic layer and the second ferromagnetic layer. The HMJJ further comprises a first superconducting material layer having a first side disposed on a second side of the first ferromagnetic layer and a second superconducting material layer having a first side disposed on a second side of the second ferromagnetic layer.

Abstract: One example includes a magnetic Josephson junction (MJJ) system. The system includes a first superconducting material layer and a second superconducting material layer each configured respectively as a galvanic contacts. The system also includes a ferrimagnetic material layer arranged between the first and second superconducting material layers and that is configured to exhibit a fixed net magnetic moment at a predetermined operating temperature of the MJJ system. The system also includes a ferromagnetic material layer arranged between the first and second superconducting material layers and that is configured to exhibit a variable magnetic orientation in response to an applied magnetic field. The MJJ system can be configured to store a binary logical value based on a direction of the variable magnetic orientation of the ferromagnetic material layer. The system further includes a spacer layer arranged between the ferromagnetic and the ferrimagnetic material layers.

Abstract: One example includes a magnetic Josephson junction (MJJ) system. The system includes a first superconducting material layer and a second superconducting material layer each configured respectively as a galvanic contacts. The system also includes a ferrimagnetic material layer arranged between the first and second superconducting material layers and that is configured to exhibit a fixed net magnetic moment at a predetermined operating temperature of the MJJ system. The system also includes a ferromagnetic material layer arranged between the first and second superconducting material layers and that is configured to exhibit a variable magnetic orientation in response to an applied magnetic field. The MJJ system can be configured to store a binary logical value based on a direction of the variable magnetic orientation of the ferromagnetic material layer. The system further includes a spacer layer arranged between the ferromagnetic and the ferrimagnetic material layers.

Abstract: A magnetic Josephson junction (MJJ) device having a ferrimagnetic/ferromagnetic (FIM/FM) exchange-biased bilayer used as the magnetic hard layer improves switching performance by effectively sharpening the hysteresis curve of the device, thereby reducing error rate when the device is used in a Josephson magnetic random access memory (JMRAM) memory cell. Thus, the materials and devices described herein can be used to build a new type of MJJ, termed a ferrimagnetic Josephson junction (FIMJJ), for use in JMRAM, to construct a robust and reliable cryogenic computer memory that can be used for high-speed superconducting computing, e.g., with clock speeds in the microwave frequency range.

Abstract: A memory cell is provided that comprises a first superconductor electrode, a second superconductor electrode, and a magnetic Josephson junction (MJJ) stack disposed between the first superconductor electrode and the second superconductor electrode. The MJJ stack includes a magnetic reference layer and a magnetic storage layer. The memory cell further comprises a magnetically stabilizing structure disposed between the MJJ stack and the second superconductor electrode, wherein the magnetic stabilizing structure magnetically couples with the magnetic reference layer to strengthen the fixed state of the magnetic reference layer.

Abstract: A buffer layer can be used to smooth the surface roughness of a galvanic contact layer (e.g., of niobium) in an electronic device, the buffer layer being made of a stack of at least four (e.g., six) layers of a face-centered cubic (FCC) crystal structure material, such as copper, the at least four FCC material layers alternating with at least three layers of a body-centered cubic (BCC) crystal structure material, such as niobium, wherein each of the FCC material layers and BCC material layers is between about five and about ten angstroms thick. The buffer layer can provide the smoothing while still maintaining desirable transport properties of a device in which the buffer layer is used, such as a magnetic Josephson junction, and magnetics of an overlying magnetic layer in the device, thereby permitting for improved magnetic Josephson junctions (MJJs) and thus improved superconducting memory arrays and other devices.

Abstract: A buffer layer can be used to smooth the surface roughness of a galvanic contact layer (e.g., of niobium) in an electronic device, the buffer layer being made of a stack of at least four (e.g., six) layers of a face-centered cubic (FCC) crystal structure material, such as copper, the at least four FCC material layers alternating with at least three layers of a body-centered cubic (BCC) crystal structure material, such as niobium, wherein each of the FCC material layers and BCC material layers is between about five and about ten angstroms thick. The buffer layer can provide the smoothing while still maintaining desirable transport properties of a device in which the buffer layer is used, such as a magnetic Josephson junction, and magnetics of an overlying magnetic layer in the device, thereby permitting for improved magnetic Josephson junctions (MJJs) and thus improved superconducting memory arrays and other devices.

Abstract: A buffer layer can be used to smooth the surface roughness of a galvanic contact layer (e.g., of niobium) in an electronic device, the buffer layer being made of a stack of at least four (e.g., six) layers of a face-centered cubic (FCC) crystal structure material, such as copper, the at least four FCC material layers alternating with at least three layers of a body-centered cubic (BCC) crystal structure material, such as niobium, wherein each of the FCC material layers and BCC material layers is between about five and about ten angstroms thick. The buffer layer can provide the smoothing while still maintaining desirable transport properties of a device in which the buffer layer is used, such as a magnetic Josephson junction, and magnetics of an overlying magnetic layer in the device, thereby permitting for improved magnetic Josephson junctions (MJJs) and thus improved superconducting memory arrays and other devices.

Abstract: A magnetic Josephson junction (MJJ) device having a ferrimagnetic/ferromagnetic (FIM/FM) exchange-biased bilayer used as the magnetic hard layer improves switching performance by effectively sharpening the hysteresis curve of the device, thereby reducing error rate when the device is used in a Josephson magnetic random access memory (JMRAM) memory cell. Thus, the materials and devices described herein can be used to build a new type of MJJ, termed a ferrimagnetic Josephson junction (FIMJJ), for use in JMRAM, to construct a robust and reliable cryogenic computer memory that can be used for high-speed superconducting computing, e.g., with clock speeds in the microwave frequency range.