2018年第65回応用物理学会春季学術講演会

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10 スピントロニクス・マグネティクス » 10.4 半導体スピントロニクス・超伝導・強相関

[20a-D104-1~11] 10.4 半導体スピントロニクス・超伝導・強相関

2018年3月20日(火) 09:00 〜 12:00 D104 (56-104)

吉野 淳二(東工大)、新屋 ひかり(横国大)

11:15 〜 11:30

[20a-D104-9] Magneto-thermopower in Ferromagnetic Semiconductor In1-xFexSb

〇(P)CONG TINH BUI1、CHRISTINA GARCIA2、NGUYEN THANH TU3、MASAAKI TANAKA3、PHAM NAM HAI1,3 (1.Tokyo Tech.、2.UCSB、3.Univ. of Tokyo)

キーワード:ferromagnetic semiconductor, magneto-thermopower, planar Nernst effect

Spin caloritronics, which studies the interaction of spin current with heat current, has recently attracted much attention due to its novel physical effects and possible applications to thermoelectric as well as spintronic devices. Among promising candidates for spin caloritronics, ferromagnetic semiconductors (FMS) are technologically interesting as they possess both ferromagnetic and semiconducting properties which could be exploited for development of more efficient energy harvesting devices. In this research, we systematically studied the transverse magneto-thermoelectric effects in an n-type In1-xFexSb (x = 16%) thin film [1], epitaxially grown on GaAs (001) substrates by molecular beam epitaxy. The sample exhibits semiconducting and ferromagnetic behavior based on resistivity, magnetization, anomalous Hall effect, and magnetic circular dichroism measurements, which show the Curie temperature of 127 K. The transverse thermal voltage Vxy increases linearly with the temperature gradient, indicating the thermoelectric origin of the effect. We find that the transverse Seebeck coefficient Sxy increases monotonically at high magnetic fields, and also increases with increasing temperature up to TC. This might be related to the negative magnetoresistance ρxx at high magnetic fields following the Mott relation Sxy ~ 1/ρxx [2]. Meanwhile, in a low magnetic field range, the polarity of Sxy depends on the angle α between the external magnetic field and the temperature gradient. Furthermore, α-dependence of Sxy at 5 K and 100 K under a magnetic field of 8 kG follows the sin(2α) function, indicating the planar Nernst effect (PNE) origin of Sxy at low fields. However, PNE is nearly temperature independent (~ 0.3 μV/K), despite the large change in the conductivity at 5 K and 100 K. Our findings are the first step toward better understanding of the magneto-thermoelectric phenomena in similar Fe-doped ferromagnetic semiconductors.

Refs. [1] N. T. Tu et al., arXiv:1706.00735. [2] Y. Pu et al., Phys. Rev. Lett. 101, 117208 (2008).