Magnetic Order in Kondo-Lattice Systems due to Electron-Electron Interactions

TL;DR

This paper demonstrates that electron-electron interactions in two-dimensional Kondo-lattice systems can induce nuclear magnetic order through a phase transition, linking low-dimensional magnetism with electron system non-analyticities.

Contribution

It reveals that electron-electron interactions enable nuclear magnetic ordering in 2D Kondo-lattice systems via a thermodynamic phase transition, with the Curie temperature increasing due to these interactions.

Findings

Nuclear spins can order magnetically in 2D electron gases due to RKKY interactions.

Electron-electron interactions enhance the Curie temperature of nuclear magnetism.

Nuclear magnetic order depends on the anomalous behavior of 2D electron spin susceptibility.

Abstract

The hyperfine interaction between the electron spin and the nuclear spins is one of the main sources of decoherence for spin qubits when the nuclear spins are disordered. An ordering of the latter largely suppresses this source of decoherence. Here we show that such an ordering can occur through a thermodynamic phase transition in two-dimensional (2D) Kondo-lattice type systems. We specifically focus on nuclear spins embedded in a 2D electron gas. The nuclear spins interact with each other through the RKKY interaction, which is carried by the electron gas. We show that a nuclear magnetic order at finite temperature relies on the anomalous behavior of the 2D static electron spin susceptibility due to electron-electron interactions. This provides a connection between low-dimensional magnetism and non-analyticities in interacting 2D electron systems. We discuss the conditions for nuclear magnetism, and show that the associated Curie temperature increases with the electron-electron interactions and may reach up into the millikelvin regime. The further reduction of dimensionality to one dimension is shortly discussed.