[17a-M_374-1~12] 10.3 スピンデバイス・磁気メモリ・ストレージ技術

10:15 〜 10:30英語発表

[17a-M_374-6] Magnetic Tunnel Junctions with Magnetic Vortex CoFeSiB-Ta Free Layer

〇Hiroto Kimijima¹, Seiya Takano¹, Takafumi Nakano^1,2, Mikihiko Oogane^1,3 (1.Tohoku Univ., 2.Green X-Tech, Tohoku Univ., 3.CSIS, Tohoku Univ.)

キーワード：

spintronics、TMR、magnetic sensor

Tunnel magnetoresistance (TMR) sensors utilizing magnetic tunnel junctions (MTJs) are high- sensitivity magnetic sensors capable of operating at room temperature. The sensitivity is defined as TMR ratio/2H_s [%/Oe], where H_s is saturation field. One of the methods to obtain a linear response is to utilize magnetic vortex structure. This structure has no domain walls; therefore, it has hysteresis-free and highly linear response. In the previous work, it was reported that high TMR ratio (180%~190%) and the sensitivity 0.6%/Oe was achieved using CoFeSiB as the free layer. To increase the sensitivity further, we leveraged a free layer CoFeSiB-Ta as a key approach. By doping CoFeSiB with Ta, the crystallization temperature increases, enabling high-temperature annealing of TMR sensors; therefore, TMR ratio and sensitivity increase. However, there are no reports of TMR sensors using CoFeSiB-Ta as a free layer. In this work, we developed MTJs using Ta-doped CoFeSiB vortex free layer and investigated their TMR effect.