17:45 〜 18:00
[12p-S302-16] Magnetic proximity effect in In1-xGaxAs/(Ga,Fe)Sb bilayers via proximity magnetoresistance
キーワード：磁気近接効果、強磁性半導体
Utilizing a magnetic proximity effect (MPE) in a non-magnetic (NM)/ferromagnetic (FM) bilayer system is a promising way for introducing ferromagnetic coupling into a high-mobility non-magnetic channel. One direct consequence of the MPE is the proximity magnetoresistance (PMR), which was demonstrated recently at an interface between a NM semiconductor InAs and a FM semiconductor (Ga,Fe)Sb. In this system, the PMR can be used to probe the spin splitting energy ΔE in the NM channel, which can be largely modulated by twenty-fold using a gate voltage. This large modulation of ΔE can be explained qualitatively by enhancement of the penetration of the electron wavefunction in the NM channel into the insulating FM side, which enhances MPE. However, the detailed mechanism of MPE at the interface of NM/FM semiconductor bilayer remains unclear and needs thorough investigations.
In this work, we prepare In1-xGaxAs (x = 0%, 5%, 7.5%, 10%)/(Ga,Fe)Sb bilayers, on which we formed field-effect-transistor structures, and investigate MPE by measuring the PMRs under various gate voltage Vg. As shown for the case of x = 5%, we are able to largely control the PMR in both sign and magnitude, which reflects the MPE change by Vg application. Our analysis of the PMR using a modified Khosla-Fischer model indicates that ΔE in the NM channel is enhanced by two factors, (i) penetration of the carrier wavefunction into the FM layer, and (ii) increasing the carrier concentration n. The carrier-induced ferromagnetism via MPE in (ii) is clearly observed in NM semiconductor. Furthermore, we also observe dependence of ΔE on the carrier relaxation time, which implies that the electron-electron interaction suppresses the enhancement of ΔE. This will be discussed in detail. These results provide insights into the mechanism of MPE at semiconductor-based FM/NM interfaces.
In this work, we prepare In1-xGaxAs (x = 0%, 5%, 7.5%, 10%)/(Ga,Fe)Sb bilayers, on which we formed field-effect-transistor structures, and investigate MPE by measuring the PMRs under various gate voltage Vg. As shown for the case of x = 5%, we are able to largely control the PMR in both sign and magnitude, which reflects the MPE change by Vg application. Our analysis of the PMR using a modified Khosla-Fischer model indicates that ΔE in the NM channel is enhanced by two factors, (i) penetration of the carrier wavefunction into the FM layer, and (ii) increasing the carrier concentration n. The carrier-induced ferromagnetism via MPE in (ii) is clearly observed in NM semiconductor. Furthermore, we also observe dependence of ΔE on the carrier relaxation time, which implies that the electron-electron interaction suppresses the enhancement of ΔE. This will be discussed in detail. These results provide insights into the mechanism of MPE at semiconductor-based FM/NM interfaces.