Two disordered phases of the beta-tin structure in binary semiconductors

Area of Science:

• Condensed matter physics
• Materials science
• Computational materials science

Background:

• The Ising model on a beta-tin structure exhibits three distinct phases: order, disorder, and frustrated ordering.
• X-ray crystallography indicates no ordered beta-tin phases at room temperature in compound semiconductors, suggesting paramagnetic or frustrated disorder.
• Understanding these phases is crucial for predicting material properties and behaviors.

Purpose of the Study:

• To investigate the phase diagram of the Ising model on a beta-tin structure.
• To determine the regimes real materials fall into using computational methods.
• To predict temperature-driven phase transitions in beta-tin structured materials.

Main Methods:

• Utilized the Ising model to simulate phase behavior on a beta-tin lattice.
• Employed density functional pseudopotential calculations.
• Analyzed x-ray crystallographic data for compound semiconductors.

Main Results:

• The Ising model on a beta-tin structure presents ordered, disordered, and frustrated ordering phases.
• Density functional calculations can differentiate between these regimes in real materials.
• Predicted two temperature-driven transitions in GaSb: ordered to frustrated order, then to disordered beta-tin structures.

Conclusions:

• The study clarifies the complex phase behavior of beta-tin structures.
• Computational methods are effective in predicting material-specific phase transitions.
• Materials like GaSb may exhibit dynamic or static disorder at room temperature, with potential for multiple phase transitions.