13:30 〜 15:30
▲ [18p-PB1-51] Temperature dependence of mangnetoelectric switching conditionof perpendicular exchange bias
キーワード：Magnetoelectric Cr2O3, Electrical-induced switching of exchange bias, Perpendicular exchange bias
Recent progress in electric field induced switching of the perpendicular exchange bias (PEB) at the magnetoelectric (ME) Cr2O3/ferromagnetic interface has achieved the isothermally reversible PEB even for the all-thin-film systems [1,2]. To realize the application in spintronics devices, it is essential to clarify the energy condition of the ME switching of the PEB. So far, the relationship between the applied magnetic field H and threshold electric field E for the ME switching of PEB was suggested: a(E-E0)H = ± 2K_AFM - J_INT/t_AFM (eq.1) (where a is a ME coefficient of Cr2O3, K_AFM and t_AFM are magnetic anisotropy energy and thickness of the Cr2O3 layer, J_INT is the interface exchange coupling, and E0 is the interfacial magnetization - induced electric field) [3]. While the previous researches on the ME switching were normally conducted at a certain temperature below the Néel temperature (T_N), in this study, to obtain a deeper understanding of the effect, we examined the temperature dependence of the energy condition for ME switching of PEB.
The Pt(1.2 nm)/Co(0.4 nm)/Au(0.5 nm)/Cr2O3(173 nm)/Pt(20 nm) stacked film was fabricated by using DC magnetron sputtering. The electric-field induced ME switching was investigated at different temperatures T (from 284 K to 296 K) by the anomalous Hall effect measurements, following the reversible isothermal approach. Using eq.1, we estimated the temperature T dependence of K_AFM,J_INT, E0. Fig. 1 shows that K_AFM,J_INT, E0 decrease as T increases. We compared the T dependence of J_INT with that of J_K, where J_K was calculated using the exchange bias field and the saturation magnetization per unit area (Fig. 1b). The result shows a bifurcated tendency between them at J_INT ~ 0.02-0.03 mJ/m2, suggesting a clear restriction of J_K by the magnetic domain wall energy of the AFM layer.
The Pt(1.2 nm)/Co(0.4 nm)/Au(0.5 nm)/Cr2O3(173 nm)/Pt(20 nm) stacked film was fabricated by using DC magnetron sputtering. The electric-field induced ME switching was investigated at different temperatures T (from 284 K to 296 K) by the anomalous Hall effect measurements, following the reversible isothermal approach. Using eq.1, we estimated the temperature T dependence of K_AFM,J_INT, E0. Fig. 1 shows that K_AFM,J_INT, E0 decrease as T increases. We compared the T dependence of J_INT with that of J_K, where J_K was calculated using the exchange bias field and the saturation magnetization per unit area (Fig. 1b). The result shows a bifurcated tendency between them at J_INT ~ 0.02-0.03 mJ/m2, suggesting a clear restriction of J_K by the magnetic domain wall energy of the AFM layer.