[14p-PA1-1~74] 10 Spintronics and Magnetics

▼ [14p-PA1-66] Efficient heat induced magnetic anisotropy change by a multiple interfacial cap layer in a magnetic tunnel junction

〇(M1)Ryota Okuno¹, Yuma Yamada¹, Minori Goto^1,2, Hikaru Nomura^1,2, Yoshishige Suzuki^1,2 (1.Osaka Univ., 2.CSRN-Osaka)

Keywords:magnetic tunnel junction

Magnetic tunnel junctions (MTJs) have attracted great attention as a next generation microwave emitter. One of the driving methods of MTJs is changing the magnetic anisotropy of the free layer by the temperature change due to Joule heating. In this system, the enhancement of the temperature change is significant. Because the temperature change is enhanced by the suppression of the heat dissipation due to high interfacial thermal resistance at a metal layer / insulation layer interface, increasing the number of interfaces may enable to enhance the heat induced magnetic anisotropy change through the temperature change. In this study, we stack a W / MgO film on the exsisting MgO barrier / FeB free layer / MgO cap structure in the MTJ, and investigate heat-controlled magnetic anisotropy (HCMA) of the MTJ with a multiple interfacial cap layer.
Film structure is buffer layer / IrMn (7) / CoFe / Ru / CoFeB pinned layer / MgO barrier (0.95) / FeB free layer (2) / MgO(0.3)|W(2)|MgO(0.4) cap / metal cap (units of nm). The measurement of the spin-torque diode effect of the MTJ under the out-of-plane magnetic field provides the perpendicular magnetic anisotropy field. Magnetic anisotropy energy is obtained by the magnetic anisotropy field and saturation magnetization. The magnetic anisotropy energy of the free layer changes linearly to the Joule heating, and the slope is the efficiency of the HCMA. As a result, the HCMA value of the MTJ with the MgO / W / MgO multiple interfacial cap is higher than that of the MTJ with only the MgO cap.