Spin textures in strongly coupled electron spin and magnetic or nuclear spin systems in quantum dots

TL;DR

This paper predicts the formation of anti-ferromagnetic spin textures in quantum dots with strongly coupled electron and nuclear spins, revealing phase transitions and symmetry-breaking phenomena relevant for spintronics and quantum computing.

Contribution

It introduces a novel theoretical framework combining ab-initio density functional and exact diagonalization to describe spin textures in strongly coupled electron-magnetic/nuclear systems in quantum dots.

Findings

Prediction of anti-ferromagnetic spin textures at low temperatures

Identification of phase diagram and critical temperature

Symmetry-breaking in charge density and magnetization

Abstract

Controlling electron spins strongly coupled to magnetic and nuclear spins in solid state systems is an important challenege in the field of spintronics and quantum computation. We show here that electron droplets with no net spin in semiconductor quantum dots strongly coupled with magnetic ion/nuclear spin systems break down at low temperature and form a non-trivial anti-ferromagnetic spatially ordered spin-texture of magneto-polarons. The spatially ordered combined electron-magnetic ion spin-texture, associated with spontaneous symmetry-breaking in the parity of electronic charge density and magnetization of magnetic ions, emerge from both ab-initio density functional approach to the electronic system coupled with mean-field approximation for the magnetic/nuclear spin system and fully mircoscopic exact diagonalization of small systems. The predicted phase diagram determines the critical temperature as a function of coupling strength and identifies possible phases of the strongly coupled spin system. This prediction may arrest fluctuations in spin system and open the way to control, manipulate and prepare magnetic and nuclear spin ensembles in semiconductor nanostructures.