Spin-droplet state of an interacting 2D electron system

Area of Science:

• Condensed matter physics
• Materials science

Background:

• Two-dimensional electron systems (2DES) in semiconductors are crucial for understanding fundamental quantum phenomena.
• High-mobility silicon metal-oxide-semiconductor field-effect transistors (Si MOSFETs) offer a versatile platform for studying 2DES.

Purpose of the Study:

• To investigate the thermodynamic properties of 2D electrons in Si MOSFETs.
• To identify and characterize novel electron states and their behavior across different phases.

Main Methods:

• Thermodynamic magnetization measurements were performed on high-mobility Si MOSFETs.
• The experiments analyzed the temperature and magnetic field dependence of magnetization.

Main Results:

• Evidence for an easily polarizable electron state was observed across a wide density range, from insulating to metallic regimes.
• Magnetization data suggests the formation of large-spin droplets in the insulating phase.
• These spin droplets were found to melt with increasing density and temperature in the metallic phase, but persisted at high densities.

Conclusions:

• A unique, easily polarizable electron state exists in 2D systems within Si MOSFETs.
• The observed spin droplets provide insights into electron correlations and phase transitions in these systems.
• The persistence of these droplets even in the metallic phase warrants further investigation into electron behavior in 2D systems.