Lattice, spin, and their interactions with other degrees of freedom are crucial for understanding properties such as thermal transportation, thermal expansion, and phase transformation with important science and engineering applications in energy materials, photonics materials, structural materials, and nano systems.
Spin waves (magnon) and phonons are strongly coupled in many ferromagnetic and antiferromagnetic structures.
Application: controlling heat flow on nanoscale, manipulating spin coherence, spintronics
Supported by: Thermal Transport Process Program, CBET, NSF
Phonons in low dimension
Lattice dynamics is significantly affected by the dimension of materials though phonon confinement and structure modification. We investigate the phonons in 2-D (thin films, thin superlattices), 1-D (nanothreads), and 0-D (quantum points, nanoparticles).
Application: photonics materials, structure materials
Materials under extreme environments
We study the structure, dynamics, and transport under extreme pressure, temperature, and magnetic field for energy applications.
Application: phonon engineering, photonics materials, van der Waals materials, thermoelectrics
Interfacial thermal transport
We study the effects of phonon anharmonicity on the interfacial thermal conductance.
Application: power electronics
Lattice dynamics can be suppressed by phonon nesting, resonance, nanostructure, doping, and many other approaches.
Application: thermal management, thermoelectrics
Negative thermal expansion
Exotic phonons may induce negative thermal expansion in structural materials through anharmonicity.
Application: controlling the thermal expansion of structural materials
Phonon anhamonicity and lifetime
Anharmonicity of materials can be probed by their temperature and pressure response, and lifetime.
Application: correlate anharmonicity and their thermodynamical effects
Frustrated magnetic ordering in antiferromagnetic materials allow abnormal spin fluctuations and competing ordering.
Applications: spintronics, quantum materials