Spin-polarized electric currents in diluted magnetic semiconductor heterostructures induced by terahertz and microwave radiation

TL;DR

This study investigates how terahertz and microwave radiation induce spin-polarized electric currents in various diluted magnetic semiconductor heterostructures, revealing enhanced effects due to magnetic ion interactions.

Contribution

It demonstrates the mechanism of spin-polarized current generation in DMS heterostructures and highlights the significant enhancement caused by exchange interactions with magnetic ions.

Findings

Photocurrent arises from spin-dependent scattering of carriers.

Magnetic ions significantly enhance current generation efficiency.

Exchange interaction causes giant Zeeman spin-splitting.

Abstract

We report on the study of spin-polarized electric currents in diluted magnetic semiconductor (DMS) quantum wells subjected to an in-plane external magnetic field and illuminated by microwave or terahertz radiation. The effect is studied in (Cd,Mn)Te/(Cd,Mg)Te quantum wells (QWs) and (In,Ga)As/InAlAs:Mn QWs belonging to the well known II-VI and III-V DMS material systems, as well as, in heterovalent AlSb/InAs/(Zn,Mn)Te QWs which represent a promising combination of II-VI and III-V semiconductors. Experimental data and developed theory demonstrate that the photocurrent originates from a spin-dependent scattering of free carriers by static defects or phonons in the Drude absorption of radiation and subsequent relaxation of carriers. We show that in DMS structures the efficiency of the current generation is drastically enhanced compared to non-magnetic semiconductors. The enhancement is caused by the exchange interaction of carrier spins with localized spins of magnetic ions resulting, on the one hand, in the giant Zeeman spin-splitting, and, on the other hand, in the spin-dependent carrier scattering by localized Mn2+ ions polarized by an external magnetic field.