09:30 〜 09:45
▼ [17a-D704-3] Development of a vertical domain wall motion memory with perpendicular magnetic anisotropy
キーワード：domain wall motion memory, spin-transfer torque, spin-orbit torque
Domain wall motion memory is promising to achieve high-density and non-violate storage as a candidate of the next-generation memory. In this memory, the logic bits are stored in domains and separated by domain walls in a ferromagnetic nanowire. By injecting electric current, the logic bits can be carried to desired storage position by domain wall motion. A vertical domain wall motion memory was designed in our previous work and simulations showed that it is possible to obtain a low critical current density Jc (<1011 A m-2 ) and a high thermal stability (Δ > 60, Δ = EB/kBT) by tuning parameters of each layer. In this research, we investigate the feasibility of this novel structure starting from a simple 1-bit sample with the composition Si-SiO2//Ta(5)/Pt(10)/[Co(0.2)/Pt(0.2)]n/Co(0.2)/Cu(3)/[Co(0.23)/Pt(0.4)]12/Ta(3)/Pt(3), n = 2, 3, 4.
The films were grown on a Si-SiO2 substrate by sputtering and fabricated by electron beam lithography as well as Ar milling to form the desired patterns. Then, SiO2 was deposited as insulator to avoid short circuit. The spin-transfer torque (STT) and spin-orbit torque (SOT) induced magnetization switching were measured through the giant magnetoresistance effect. A sudden change of resistance was observed by sweeping the out-of-plane magnetic field which indicates the strong perpendicular magnetic anisotropy provided by Co/Pt multilayers. When the current pulse was injected into the pillar, the free layer reversed by STT and the pillar magnetization was switched between parallel and anti-parallel states. The writing process using SOT induced by spin Hall effect was also observed in this device.
The films were grown on a Si-SiO2 substrate by sputtering and fabricated by electron beam lithography as well as Ar milling to form the desired patterns. Then, SiO2 was deposited as insulator to avoid short circuit. The spin-transfer torque (STT) and spin-orbit torque (SOT) induced magnetization switching were measured through the giant magnetoresistance effect. A sudden change of resistance was observed by sweeping the out-of-plane magnetic field which indicates the strong perpendicular magnetic anisotropy provided by Co/Pt multilayers. When the current pulse was injected into the pillar, the free layer reversed by STT and the pillar magnetization was switched between parallel and anti-parallel states. The writing process using SOT induced by spin Hall effect was also observed in this device.