15:30 〜 15:45
▲ [11p-M101-9] Choking nonlocal magnetic damping in exchange-biased ferromagnets
キーワード：Antiferromagnet, Exchange bias
The Gilbert damping constant, α, is one of the important parameters characterizing the magnetization dynamics. It influences the switching speed of the magnetization and also determines the threshold current for various spin-torque-related phenomena [1]. It is, however, one of the least experimentally controllable magnetic parameters. Recently, we have revisited the mechanism of the non-local damping with the exchange biased ferromagnet (FM)/antiferromagnet (AFM) multilayers and showed that the non-local damping was influenced by the Néel order in the AFM [2]. These results indeed offer a control of the magnetic damping by the magnetic order in the adjacent AFM.
In this work, we particularly investigated the temperature dependence of the non-local damping in the exchange biased AFM/FM multilayer. α was characterized for the magnetization pointing along the exchange bias (EB) direction and against the EB direction by ferromagnetic resonance at elevated temperatures.
Figure 1 (a) shows the temperature dependence of α in Pt (5nm)/FeMn (tFeMn = 0 and 20nm)/FeNi (4nm). While α for tFeMn = 0 nm slightly increases with the temperature, α for tFeMn = 20 nm drastically decreases with increasing temperature. We also found that α measured against the EB is always greater than that measured along the EB. As shown in Fig. 1 (b), the difference (Δα) is linearly correlated with the strength of the EB, which is consistent with our previous observation [2]. The results essentially indicate that the non-local damping can be controlled by the adjacent antiferromagnet and its temperature dependent exchange bias. We also point out that such a strong temperature dependent damping may be very beneficial for spintronic applications involving a Joule heating upon the operation [3].
In this work, we particularly investigated the temperature dependence of the non-local damping in the exchange biased AFM/FM multilayer. α was characterized for the magnetization pointing along the exchange bias (EB) direction and against the EB direction by ferromagnetic resonance at elevated temperatures.
Figure 1 (a) shows the temperature dependence of α in Pt (5nm)/FeMn (tFeMn = 0 and 20nm)/FeNi (4nm). While α for tFeMn = 0 nm slightly increases with the temperature, α for tFeMn = 20 nm drastically decreases with increasing temperature. We also found that α measured against the EB is always greater than that measured along the EB. As shown in Fig. 1 (b), the difference (Δα) is linearly correlated with the strength of the EB, which is consistent with our previous observation [2]. The results essentially indicate that the non-local damping can be controlled by the adjacent antiferromagnet and its temperature dependent exchange bias. We also point out that such a strong temperature dependent damping may be very beneficial for spintronic applications involving a Joule heating upon the operation [3].