Interacting spin-droplets and magnetic properties of a low-density two-dimensional electron gas

Abstract

We argue that the magnetic susceptibility data, Refs. 1-3, for the low-density two-dimensional (2D) silicon-based electron gas indicate that magnetically active electrons are localised in spin-droplets. The droplets exist in both the insulating and metallic phases, and interact ferromagnetically, forming an effective 2D Heisenberg ferromagnet. Comparing the data with known analytical and numerical results for a 2D Heisenberg ferromagnet, we determine that JS^2 \approx 0.6K, where S is the spin of the droplet and J is the ferromagnetic exchange constant between droplets. We further argue that most likely S=1 with four electrons occupying each droplet on average. We discuss the dependence of the magnetic susceptibility and the specific heat on the external magnetic field, which follows from the model, and hence we suggest further experimental tests of the model.

References in corpus (7)

• Metal-insulator transition in two-dimensional electron systems
• Metal-Insulator Transition in Disordered Two-Dimensional Electron Systems
• Theoretical Studies of Superconductor-Insulator Transitions
• Spin-Droplet State of an Interacting 2D Electron System
• Thermodynamics of Heisenberg ferromagnets with arbitrary spin in a magnetic field
• Thermodynamic magnetization of two-dimensional electron gas measured over wide range of densities
• Electron correlations in two-dimensional small quantum dots

Cited by in corpus (4)

• Novel Energy Scale in the Interacting 2D Electron System Evidenced from Transport and Thermodynamic Measurements
• Probing spin susceptibility of a correlated two-dimensional electron system by transport and magnetization measurements
• Magnetic-field-driven redistribution between extended and localized electronic states in high-mobility Si MOSFETs at low temperatures
• Phase Separation in Two-Dimensional Electron Systems: Experimental View