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[18a-E216-3] Magnetic anisotropy switching from perpendicular to in-plane with temperature
in heavily-Fe-doped ferromagnetic semiconductor (Ga,Fe)Sb
Keywords:Ferromagnetic Semiconductor, Ferromagnetic Resonance, Magnetic Anisotropy
Ferromagnetic semiconductors (FMSs) with high Curie temperature Tc are strongly required for spintronics device applications. So far, the mainstream study of FMSs is Mn-doped III-V FMSs; however they are only p-type and Tc is much lower than 300 K. Recently, we have grown Fe-doped FMSs, such as (Ga,Fe)Sb with high Tc [> 300 K][1] which are promising for spintronics applications. In order to use (Ga,Fe)Sb, understanding its magnetic anisotropy (MA) is essential.
Recently, we found that in (Ga0.7,Fe0.3)Sb thin films, the MA changes from in-plane magnetic anisotropy (IMA) to perpendicular magnetic anisotropy (PMA) with increasing the thickness from 15 nm to 55 nm [2]. Here, we report on the temperature dependence of the MA of a 40 nm thick (Ga0.7,Fe0.3)Sb film grown on AlSb/semi-insulating GaAs(001) substrates by low-temperature molecular-beam epitaxy (LT-MBE). We estimated the MA constants of the film by measuring the ferromagnetic resonance (FMR) and magnetization using superconducting quantum interference device (SQUID) magnetometry. We estimated the perpendicular MA energy Ep as a function of temperature. When we decrease the temperature from 300 K to 10 K, Ep changes its sign from positive to negative, indicating a switching from IMA to PMA. From microstructure characterizations, we attribute the origin of this temperature dependence to the fluctuation in the local Fe density, which causes nano-columnar-like Fe-rich regions growth. PMA at low temperature may be due to the dominant magnetization alignment along the perpendicular direction inside these nanocolumns.
This work was partly supported by Grants-in-Aid for Scientific Research (Nos. 26249039, 17H04922, 16H02095, and 18H03860), CREST of JST (JPMJCR1777), and Spin-RNJ.
Refs: [1] N. T. Tu et al., PRB 92, 144403 (2015); APL 108, 192401 (2016). [2] S. Goel et al., PRM, submitted.
Recently, we found that in (Ga0.7,Fe0.3)Sb thin films, the MA changes from in-plane magnetic anisotropy (IMA) to perpendicular magnetic anisotropy (PMA) with increasing the thickness from 15 nm to 55 nm [2]. Here, we report on the temperature dependence of the MA of a 40 nm thick (Ga0.7,Fe0.3)Sb film grown on AlSb/semi-insulating GaAs(001) substrates by low-temperature molecular-beam epitaxy (LT-MBE). We estimated the MA constants of the film by measuring the ferromagnetic resonance (FMR) and magnetization using superconducting quantum interference device (SQUID) magnetometry. We estimated the perpendicular MA energy Ep as a function of temperature. When we decrease the temperature from 300 K to 10 K, Ep changes its sign from positive to negative, indicating a switching from IMA to PMA. From microstructure characterizations, we attribute the origin of this temperature dependence to the fluctuation in the local Fe density, which causes nano-columnar-like Fe-rich regions growth. PMA at low temperature may be due to the dominant magnetization alignment along the perpendicular direction inside these nanocolumns.
This work was partly supported by Grants-in-Aid for Scientific Research (Nos. 26249039, 17H04922, 16H02095, and 18H03860), CREST of JST (JPMJCR1777), and Spin-RNJ.
Refs: [1] N. T. Tu et al., PRB 92, 144403 (2015); APL 108, 192401 (2016). [2] S. Goel et al., PRM, submitted.