Effect of phonon-phonon interactions on localization.

Area of Science:

• Classical mechanics
• Condensed matter physics
• Statistical mechanics

Background:

• Disordered systems exhibit unique transport properties.
• Heat current (J) in low dimensions is sensitive to disorder and boundary conditions.
• Localized modes in harmonic systems prevent efficient energy transport.

Purpose of the Study:

• To investigate the impact of anharmonicity on heat current in a classical 1D disordered chain.
• To understand the transition from localized to diffusive energy transport.
• To analyze the dependence of heat current on system size (N).

Main Methods:

• Simulations of a classical one-dimensional disordered chain.
• Connecting chain ends to stochastic thermal reservoirs at different temperatures.
• Analyzing the heat current (J) under varying degrees of anharmonicity.

Main Results:

• In the absence of anharmonicity, all modes are localized, leading to exponential decay of J with system size (N).
• Even minimal anharmonicity induces a transition to diffusive energy transport.
• The heat current (J) exhibits an approximate 1/N dependence on system size (N) with anharmonicity.

Conclusions:

• Anharmonicity is crucial for enabling diffusive energy transport in such systems.
• The transition from localized to diffusive transport is sensitive to anharmonic effects.
• Findings suggest potential for engineering thermal conductivity in disordered materials.