09:45 〜 10:00
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[18a-E216-2] Giant rectification effect in semiconductor-based
non-magnetic InAs / ferromagnetic (Ga,Fe)Sb bilayer heterostructures
キーワード：Spintronics, Ferromagnetic Semiconductor, non-reciprocal phenomena
Recently, unidirectional magnetoresistance (UMR), which shows odd function behavior against an external magnetic field, is observed in a system with a space symmetry breaking under a static electric and magnetic field (E and B). This UMR magnitude is expressed by |I·E×B|, where I is an electric current. Although this effect gives us an insight into the symmetry in materials, it is very weak and hard to detect.
It is experimentally confirmed that the UMR magnitude is proportional to the current density. Therefore, a narrower cross-sectional path of carriers should be effective to increase UMR. Here, we focus on a one-dimensional (1D) edge channel in a semiconductor heterostructure originated from the Fermi level pinning and demonstrate giant UMR observed with DC currents in nonmagnetic semiconductor InAs / ferromagnetic semiconductor (Ga,Fe)Sb bilayers. (Ga,Fe)Sb is a p-type ferromagnetic semiconductor with high Curie temperature (> 300 K). Our InAs/(Ga,Fe)Sb bilayer heterostructures have a small lattice mismatch (< 0.6%) and staggered band diagram. Thus, we can obtain high-quality Rashba system with ferromagnetic coupling in the semiconductor heterostructures. As a result of the transport measuremen, we observe a clear Shubunikov de Haas oscillation and a large odd-functoin component Rodd.
Triangular potentials are formed at the side surface of InAs, leading to E parallel to the y direction. When I and B is applied to the x and z direction, respectively, |I·E×B| is maximized. The UMR magnitude is expressed as UMR = R(B) − R(−B) = 2γR(0)|I||B|, where γ is an index of UMR: We found that γ is estimated to be 1.4×104 [A−1T−1] in our bilayers and this value is much larger than that reported in other systems by 4 - 7 orders of magnitude.
It is experimentally confirmed that the UMR magnitude is proportional to the current density. Therefore, a narrower cross-sectional path of carriers should be effective to increase UMR. Here, we focus on a one-dimensional (1D) edge channel in a semiconductor heterostructure originated from the Fermi level pinning and demonstrate giant UMR observed with DC currents in nonmagnetic semiconductor InAs / ferromagnetic semiconductor (Ga,Fe)Sb bilayers. (Ga,Fe)Sb is a p-type ferromagnetic semiconductor with high Curie temperature (> 300 K). Our InAs/(Ga,Fe)Sb bilayer heterostructures have a small lattice mismatch (< 0.6%) and staggered band diagram. Thus, we can obtain high-quality Rashba system with ferromagnetic coupling in the semiconductor heterostructures. As a result of the transport measuremen, we observe a clear Shubunikov de Haas oscillation and a large odd-functoin component Rodd.
Triangular potentials are formed at the side surface of InAs, leading to E parallel to the y direction. When I and B is applied to the x and z direction, respectively, |I·E×B| is maximized. The UMR magnitude is expressed as UMR = R(B) − R(−B) = 2γR(0)|I||B|, where γ is an index of UMR: We found that γ is estimated to be 1.4×104 [A−1T−1] in our bilayers and this value is much larger than that reported in other systems by 4 - 7 orders of magnitude.