Sign-reversal electron magnetization in Mn-doped semiconductor structures

TL;DR

This paper demonstrates that in Mn-doped semiconductor structures, optical excitation can induce a reversal of electron magnetization through interactions between different Mn impurity types, with potential for experimental observation via polarized photoluminescence.

Contribution

It reveals a novel optical mechanism for electron spin reversal in Mn-doped semiconductors involving impurity interactions and provides insights into controlling magnetization.

Findings

Electron magnetization can be reversed by optical excitation in Mn-doped structures.

The spin reversal is due to impurity-to-band excitation and electron capture by interstitial Mn.

At higher excitation, the electron spin polarization returns to normal, confirming the reversible nature.

Abstract

The diversity of various manganese types and its complexes in the Mn-doped ${\rm A^{III}B^V}$ semiconductor structures leads to a number of intriguing phenomena. Here we show that the interplay between the ordinary substitutional Mn acceptors and interstitial Mn donors as well as donor-acceptor dimers could result in a reversal of electron magnetization. In our all-optical scheme the impurity-to-band excitation via the Mn dimers results in direct orientation of the ionized Mn-donor $d$ shell. A photoexcited electron is then captured by the interstitial Mn and the electron spin becomes parallel to the optically oriented $d$ shell. That produces, in the low excitation regime, the spin-reversal electron magnetization. As the excitation intensity increases the capture by donors is saturated and the polarization of delocalized electrons restores the normal average spin in accordance with the selection rules. A possibility of the experimental observation of the electron spin reversal by means of polarized photoluminescence is discussed.