Observation of a two-dimensional spin-lattice in non-magnetic semiconductor heterostructures

TL;DR

This paper reports the discovery of an intrinsic 2D spin-lattice in high-mobility GaAs/AlGaAs heterostructures, revealing localized spins that interact via RKKY exchange, enabling new spin-based quantum functionalities.

Contribution

It demonstrates the existence of an intrinsic, disorder-bound 2D spin-lattice in non-magnetic semiconductor heterostructures, a novel source of localized spins without magnetic impurities.

Findings

Localized spins are observed in high-mobility heterostructures.

Spins interact via RKKY exchange below 100 mK.

The spin system mimics a 2D lattice-Kondo model.

Abstract

Tunable magnetic interactions in high-mobility nonmagnetic semiconductor heterostructures are centrally important to spin-based quantum technologies. Conventionally, this requires incorporation of "magnetic impurities" within the two-dimensional (2D) electron layer of the heterostructures, which is achieved either by doping with ferromagnetic atoms, or by electrostatically printing artificial atoms or quantum dots. Here we report experimental evidence of a third, and intrinsic, source of localized spins in high-mobility GaAs/AlGaAs heterostructures, which are clearly observed in the limit of large setback distance (=80 nm) in modulation doping. Local nonequilibrium transport spectroscopy in these systems reveals existence of multiple spins, which are located in a quasi-regular manner in the 2D Fermi sea, and mutually interact at temperatures below 100 milliKelvin via the Ruderman-Kittel-Kasuya-Yosida (RKKY) indirect exchange. The presence of such a spin-array, whose microscopic origin appears to be disorder-bound, simulates a 2D lattice-Kondo system with gate-tunable energy scales.