Abstract: A method for synthesis of high anisotropy L10 FeNi (tetrataenite) thin films is provided that combines physical vapor deposition via atomic layer sputtering and rapid thermal annealing with extreme heating and cooling speeds. The methods can induce L10-ordering in FeNi thin films. The process uses a base composite film of a support substrate, a seed layer, a multilayer thin film of FeNi with alternating single atomic layers of Fe and Ni that mimics the atomic plane of the final L10 FeNi alloy, and a capping layer. The Fe and Ni bilayers are grown on top of a Si substrate with a thermally oxidized SiO2 seed layer to mechanically strain the sample during rapid thermal annealing.

Abstract: A method for synthesis of high anisotropy L10 FeNi (tetrataenite) thin films is provided that combines physical vapor deposition via atomic layer sputtering and rapid thermal annealing with extreme heating and cooling speeds. The methods can induce L10-ordering in FeNi thin films. The process uses a base composite film of a support substrate, a seed layer, a multilayer thin film of FeNi with alternating single atomic layers of Fe and Ni that mimics the atomic plane of the final L10 FeNi alloy, and a capping layer. The Fe and Ni bilayers are grown on top of a Si substrate with a thermally oxidized SiO2 seed layer to mechanically strain the sample during rapid thermal annealing.

Abstract: A method for fabricating artificial skyrmions and skyrmion lattices with a stable ground state at room temperature and in the absence of magnetic fields is provided. The lattices are formed by patterning vortex-state nanodots over macroscopic areas on top of an underlayer with perpendicular magnetic anisotropy (PMA); and preparing artificial skyrmion lattices using ion irradiation to suppress PMA in the underlayer and allow imprinting of the vortex structure from the nanodots to form the skyrmion lattices. Alternatively the skyrmions can be formed by ion-irradiating select asymmetric nanodot regions of the PMA underlayer, leading to planar skyrmions without nanodot protrusions. These artificial skyrmions can be used for low dissipation information storage, such as magnetic memory, logic devices and sensors.

Abstract: Ultralow density ionic material foams, with density approaching 0.1% of the bulk density, and synthesis methods using interconnected metallic nanowires are provided. Nanowires of various sizes and metals are dispersed into a freezable liquid through a suitable fluid exchange. Surface treatments ensure that nanowires remain sufficiently metallic and physically separated. Wire-liquid solutions can be dropped directly into liquid nitrogen in the form of droplets or placed into molds of various shapes. A freeze drying technique is employed to turn the resulting ice-wire mixture into a freestanding, low-density foam composed of interlocked nanowires. Sintering or oxidation and reduction treatment of the foam material at elevated temperatures is used to connect the nanowires into an interconnected metallic foam. Metals of the metal foams are then processed into ionic materials including oxides, nitrides, chlorides, hydrides, fluorides, iodides and carbides.

Abstract: Ultralow density pure metal foams, with density approaching 0.1% of the bulk density, and synthesis methods using interconnected metallic nanowires are provided. Nanowires of various sizes and metals are synthesized by electrodeposition into nanoporous templates such as anodized aluminum oxide or polycarbonate. The templates are etched away and the nanowires are dispersed into water through a suitable fluid exchange. Surface treatments ensure that nanowires remain sufficiently metallic and physically separated. Wire-water solutions can be dropped directly into liquid nitrogen in the form of droplets or placed into molds of various shapes. A freeze drying technique is employed to turn the resulting ice-wire mixture into a freestanding, low-density foam composed of interlocked nanowires. Finally, sintering or oxidation and reduction treatment of the foam material at elevated temperatures is used to connect the nanowires into an interconnected metallic foam, greatly improving the strength of the structure.

Abstract: A method for fabricating artificial skyrmions and skyrmion lattices with a stable ground state at room temperature and in the absence of magnetic fields is provided. The lattices are formed by patterning vortex-state nanodots over macroscopic areas on top of an underlayer with perpendicular magnetic anisotropy (PMA); and preparing artificial skyrmion lattices using ion irradiation to suppress PMA in the underlayer and allow imprinting of the vortex structure from the nanodots to form the skyrmion lattices. Alternatively the skyrmions can be formed by ion-irradiating select asymmetric nanodot regions of the PMA underlayer, leading to planar skyrmions without nanodot protrusions. These artificial skyrmions can be used for low dissipation information storage, such as magnetic memory, logic devices and sensors.