The possibility of an intrinsic spin lattice in high-mobility semiconductor heterostructures

Abstract

Embedding magnetic moments into semiconductor heterostructures offers a tuneable access to various forms of magnetic ordering and phase transitions in low-dimensional electron systems. In general, the moments are introduced artificially, by either doping with ferromagnetic atoms, or electrostatically confining odd-electron quantum dots. Here, we report experimental evidence of an independent, and intrinsic, source of localized spins in high-mobility GaAs/AlGaAs heterostructures with large setback distance (≈80 nm) in modulation doping. Measurements reveal a quasi-regular distribution of the spins in the delocalized Fermi sea, and a mutual interaction via the Ruderman-Kittel-Kasuya-Yosida (RKKY) indirect exchange below 100 mK. We show that a simple model on the basis of the fluctuations in background potential on the host two-dimensional electron system can explain the observed results quantitatively, which suggests a 'disorder-templated' microscopic origin of the localized moments. ©2007 Nature Publishing Group.