13:30 〜 15:30
▲ [19p-P1-43] Effect of voltage on the magneto-static spin waves in magnetic tunnel junction with perpendicular magnetization
キーワード：Voltage Induced Phenomena,TE-FMR,MgO-MTJ
Voltage effects on the magnetic properties are being actively studied because of its expectations to provide new functions in the spintronics devices. The magnetic anisotropy (Fe/MgO) [1], the Curie temperature (Co) [2], as well as the asymmetric exchange interaction (DMI) [3] have been successfully controlled by external voltage. In this work, we analyze the voltage induced changes of eigen-mode frequencies of the magnetic resonance in the 100 nm circular perpendicular magnetized FeB nanomagnets to characterize the voltage controlled exchange interaction.
We prepared CoFeB (2 nm)/MgO/FeB(2 nm) magnetic tunnel junctions (MTJs) by magnetron sputtering systems. The designed junction has a circular shape (100 nm). The resistance area product and magnetoresistance ratio were 5.34 Ωμm2 and 92%, respectively. Since the CoFeB reference layer has an in-plane magnetization, the MTJ is very sensitive to the fluctuation of the FeB free layer magnetization along the perpendicular direction. Thermally excited ferromagnetic resonance (TE-FMR) [4] spectra were measured with spectrum analyzer using lock-in technique. The block diagram of the measurement setup is shown in Fig. 1(a). Typical TE-FMR spectra which were taken at 4.0 GHz under different voltage application are shown in Fig. 1(b). From the voltage-induced change in eigen-mode frequencies, we evaluate the voltage modulation mechanism by comparison with micromagnetic simulations.
This work was supported by ImPACT Program of Council for Science, Technology and Innovation.
1. T. Murayama et al., Nat. Nanotech. 4, 158-161 (2009).
2. D. Chiba et al., Nat. Mater. 10, 853-856 (2011).
3. K. Nawaoka et al., Appl. Phys. Expr. 8, 0640041-0630044 (2015).
4. S. Tamaru et al., J. Appl. Phys. 115, 17C7401-17C7403 (2014).
We prepared CoFeB (2 nm)/MgO/FeB(2 nm) magnetic tunnel junctions (MTJs) by magnetron sputtering systems. The designed junction has a circular shape (100 nm). The resistance area product and magnetoresistance ratio were 5.34 Ωμm2 and 92%, respectively. Since the CoFeB reference layer has an in-plane magnetization, the MTJ is very sensitive to the fluctuation of the FeB free layer magnetization along the perpendicular direction. Thermally excited ferromagnetic resonance (TE-FMR) [4] spectra were measured with spectrum analyzer using lock-in technique. The block diagram of the measurement setup is shown in Fig. 1(a). Typical TE-FMR spectra which were taken at 4.0 GHz under different voltage application are shown in Fig. 1(b). From the voltage-induced change in eigen-mode frequencies, we evaluate the voltage modulation mechanism by comparison with micromagnetic simulations.
This work was supported by ImPACT Program of Council for Science, Technology and Innovation.
1. T. Murayama et al., Nat. Nanotech. 4, 158-161 (2009).
2. D. Chiba et al., Nat. Mater. 10, 853-856 (2011).
3. K. Nawaoka et al., Appl. Phys. Expr. 8, 0640041-0630044 (2015).
4. S. Tamaru et al., J. Appl. Phys. 115, 17C7401-17C7403 (2014).