Welcome to the Liu Research Group
The Liu Research Group at NC State studies how heat, spin, and orbital angular momentum move through materials at the nanoscale, and uses that understanding to design new materials for energy, water, and quantum information technologies. Recent discoveries from our group include the chiral-phonon-activated spin Seebeck effect (Nature Materials, 2023), the chiral-phonon-induced orbital Seebeck effect (Nature Physics, 2026), and a fully dense solid with thermal conductivity approaching that of air (Science Advances, 2026).
We combine ultrafast laser-based pump-probe measurements (TDTR and TR-MOKE) with atomistic simulations (molecular dynamics, density functional theory, and lattice dynamics). Our current research has three main directions: converting energy into information with chiral phonons, pushing the lower limit of thermal conductivity in solids, and actively controlling heat transport. We also study water and soft matter at the nanoscale. Together, this work provides building blocks for thermal management, energy conversion and storage, and low-power information devices.
Our graduate students are motivated to learn and enjoy solving multidisciplinary, challenging problems. They gain experience across optics, electronics, thermal science, materials, and solid-state physics.
If you want to see how the Nanoscale Thermal Transport Lab looks like, please click this 3D interactive video link: https://my.matterport.com/show/?m=GjZsFZ5UK2D
If you want to see the shared lab facility, please click this link: https://my.matterport.com/show/?m=J7WeZYuups1
(Updated on June 2026)
We have Ph.D. and postdoc openings in the group now. If you are interested to check, you can send an email to [email protected], and attach your CV and transcripts. Please also state your past experience and skill sets in the email.
We have thesis-based master student position openings in the group. Highly-motivated students who perform well during the master period can also be converted to Ph.D. students.
Chiral-phonon-activated spin Seebeck (CPASS) effect, Chiral phonon induced orbital Seebeck effect (CPOSE), and Chirality-induced spin selectivity (CISS) in chiral materials
We recently reported the spin current generation in an adjacent metallic layer attached to a non-magnetic chiral hybrid organic-inorganic perovskites when subjected to a thermal gradient, induced by chiral phonons possessing angular momentum. This work has been published in Nature Materials. Another effect found recently is the orbital current generation in an adjacent metallic layer attached to chiral quartz. This work has been published in Nature Physics. This funded Multi-University Research Project will explore the fundamental mechanisms of the transport and interactions of chiral phonons.
We also find that when injecting pure spin into chiral materials, direction matters. This work has been published in Science Advances.
Our follow-up work shows giant anisotropic spin absorption in chiral hybrid semiconductors. This work has been published in Advanced Materials (2026).
We also showed that an electric field can reverse phonon chirality in a ferroelectric crystal, coupling ferroelectricity and phonon chirality. This work has been published in Nature Communications (2026).
Pushing the Lower Limit of Thermal Conductivity: 2D Materials, van der Waals Heterostructures, and Hybrid Perovskites
Thermal conductivity of 2D materials and van der Waals heterostructures is of interest for energy storage, nanoelectronics, and optoelectronics. The effect of defects and disorders is important to know. We simulated the effect of mass disorder and stacking disorder on the anisotropic thermal conductivity using MD. We also measured the effect of structural and compositional disorders by TDTR and other characterization tools. See our recent work at Nature Communications. This NSF-funded project will explore the mechanism of thermal transport in layered materials and push the lower limit of thermal conductivity.
Recently we published in ACS Nano to show the anomalous dependence of thermal conductivity and elastic modulus in two-dimensional hybrid organic-inorganic metal halide perovskites.
Most recently, we demonstrated a rigid, fully dense layered hybrid perovskite with thermal conductivity approaching that of air. This work has been published in Science Advances (2026).
Domain wall engineering of thermal conductivity in ferroelectric materials and In-situ imaging of domain wall dynamics
We recently demonstrated the thermal conductivity modulation at room temperature in bulk scale (millimeter thick) using ferroelectric PMN-PT single crystals. Thermal conductivity measurements can be used as an alternative method to indicate the domain wall density and distribution in ferroelectric materials after poling. This work has been published in Advanced Materials. This NSF-funded project will explore the possibilities of using ferroelectric materials as a thermal switch.
We also find how to solve the long-standing challenge for piezoelectric materials, to electrically de-pole and re-pole piezoelectric crystals without heat treatment. This work has been published in Nature Communications.
We also imaged ferroelectric domain wall dynamics in real time during electric poling and depoling. This work has been published in Advanced Science (2026).
Modeling Water Evaporation and Condensation Dynamics at the Nanoscale
Understanding the water state and water dynamics for evaporation and condensation is essential for many engineering systems. We recently applied a methodology to achieve steady-state water evaporation and condensation in molecular dynamics simulations and used this modeling system to investigate the water dynamics in fibrous membranes and hydrogels. See our recent work at the Journal of Molecular Liquids. We also showed that oscillations in the incident electric field enhance interfacial water evaporation, published in Materials Horizons (2025). This NSF-funded project will explore the rational design of membranes for water desalination.
Anisotropic and Strain Effects in Polymers and Hydrogels
Thermal transport in the axial direction of polymer fibers has been extensively studied, while the thermal conductivity in the radial direction remains unknown. Because polymer fiber is an important type of high anisotropic materials, we measured the strain effect of thermal conductivity in the radial direction using TDTR (ACS Macro Letters) and simulated this effect using MD(Applied Physics Letters). This NWI-funded project will explore the mechanical response of polymers and hydrogels.
More research and publications here.
October 2026 Our work on giant anisotropic spin absorption in chiral hybrid semiconductors has been published in Advanced Materials!
September 2026 Our work on extremely low thermal conductivity in rigid layered hybrid perovskites has been published in Science Advances!
May 2026 Our work on coupled ferroelectricity and phonon chirality has been published in Nature Communications!
May 2026 Ziqi Wang and Saqlain Raza have graduated with their Ph.D. degrees! Congratulations, Dr. Wang and Dr. Raza!
March 2026 Aryan Jouneghaninaseri won 2nd place in the MAE Graduate Research Symposium poster competition!