[25a-P01-1~51] 10 Spintronics and Magnetics (Poster)

English Presentation

[25a-P01-51] Spin-orbit-torque-induced magnetization switching in 75^o-canted MTJ

〇Anh ThiVan Nguyen^1,2, Hiroshi Naganuma^1,2,3,4, Hiroaki Honjo², Shoji Ikeda^1,2, Tetsuo Endoh^1,2,5,6 (1.CSIS, Tohoku Univ., 2.CIES, Tohoku Univ., 3.NAIAS, Nagoya Univ., 4.IMaSS, Nagoya Univ., 5.ECEI, Tohoku Univ., 6.RIEC, Tohoku Univ.)

Keywords:

SOT-MRAM,Ultrafast switching,Canted MTJ

SOT-induced magnetization switching has been widely investigated for high-performance MRAMs. So far, we have demonstrated the 0.35 ns field-free switching in canted SOT devices with 88 nm x 315 nm MTJ. For the SRAM replacement, a faster switching time and a lower switching current in a smaller MTJ are required for the low power consumption and high-density MRAM. Thus, a thoughtful simulation is necessary to support the experimental results efficiently. Herein, we investigate the change in SOT-induced magnetization switching in a 75deg-canted MTJ against a channel line by using micro-magnetic simulations under the influence of the effective anisotropy (Hk), and the field-like coefficient (b), i.e., the ratio between the field-like torque and the Slonczewski-like torque. The 10 nm x 30 nm elliptic MTJ device model was designed so that the current was applied in a direction that was 75deg-canted along the long axis of the MTJ. The free layer has an in-plane easy axis with an effective out-of-plane magnetic anisotropy field of Hk, including the bulk anisotropy field, the interfacial anisotropy field, and the demagnetization field. Fig. 1 (a) shows the time evolution of the magnetization for two devices with Hk = -0.9 T and Hk = -0.08 T. The switching time (t) is when the magnetization of the free layer is switched from the P state to the AP state. t for the former is 0.32 ns while t for the latter is 0.19 ns. As a result, the voltage for the P-AP switching at a pulse width of 0.35 ns in the latter (0.205 V) is 30% smaller than that for the former (0.295 V) (Fig. 1 (b)). Fig. 1 (c) shows the b dependence of t for two devices. When b increases, t decreases and can be reduced to 0.03 ns by increasing b to 1 in the device with Hk = - 0.08 T. To achieve the same result in the device with Hk = - 0.9 T, b must be increased to 6. These results indicate a way to achieve ultrafast field-free SOT switching of a few tens of ps in nm-sized MTJ devices.