Related Experiment Video
Updated: Jul 1, 2025
11:42
Fabrication of Gate-tunable Graphene Devices for Scanning Tunneling Microscopy Studies with Coulomb Impurities
Published on: July 24, 2015
15.4K
Moiré Pattern Controlled Phonon Polarizer Based on Twisted Graphene.
Zihao Qin1, Lingyun Dai1, Man Li1
1Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, Los Angeles, CA, 90095, USA.
Advanced Materials (Deerfield Beach, Fla.)
|March 2, 2024
Summary
Researchers demonstrated a phonon polarizer using twisted graphene, significantly modulating thermal conductance by up to 631% with Moiré patterns. This opens new possibilities for thermal management in nanoelectronics.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Nanotechnology
Background:
- Twisted van der Waals materials with Moiré patterns exhibit unique properties.
- Thermal transport in Moiré systems is crucial for nanoelectronics and thermal management but underexplored.
- Graphene's tunable electronic and optical properties make it a promising candidate for Moiré studies.
Purpose of the Study:
- To experimentally investigate thermal transport across twisted graphene Moiré superlattices.
- To demonstrate the concept of a phonon polarizer based on rotational misalignment.
- To understand the fundamental mechanisms governing phonon transmission in Moiré structures.
Main Methods:
- Direct thermal and acoustic measurements.
- Structural characterizations.
- Atomistic modeling using density functional theory (DFT) and molecular dynamics (MD) simulations.
Main Results:
- Achieved up to 631% modulation in thermal conductance by varying Moiré angles.
- Maintained high acoustic transmission across the twisted graphene layers.
- Quantified mode-dependent phonon transmission, attributing it to the coupling of flexural phonon modes.
Conclusions:
- Rotational misalignment in twisted graphene acts as an effective phonon polarizer.
- Thermal transport can be precisely tuned by controlling Moiré angles, impacting high-frequency thermal modes.
- This work provides fundamental insights for designing novel quantum thermal devices and manipulating vibrational properties.
Related Concept Videos
01:31Dielectric Polarization in a Capacitor
4.7K
The presence of a dielectric medium in a capacitor not only changes the voltage and capacitance but also affects the electric field. In general, dielectrics can be of two types: polar and nonpolar. In a polar dielectric, the positive and negative charges in the molecules are separated by a distance and hence have a permanent dipole moment. In contrast, no such charge separation exists in a nonpolar dielectric, however the nonpolar molecules get polarized in the presence of an external electric...
4.7K
01:29Potential Due to a Polarized Object
403
A neutral atom consists of a positively charged nucleus surrounded by a negatively charged electron cloud. When placed in an external electric field, the external electric force pulls the electrons and nucleus apart, opposite to the intrinsic attraction between the nucleus and the electrons. The opposing forces balance each other with a slight shift between the center of masses of the nucleus and the electron cloud, resulting in a polarized atom. On the other hand, a few molecules, like water,...
403
01:28Induced Electric Dipoles
4.2K
A permanent electric dipole orients itself along an external electric field. This rotation can be quantified by defining the potential energy because the external torque does work in rotating it. Then, the potential energy is minimum at the parallel configuration and maximum at the antiparallel configuration. While the former is a stable equilibrium, the latter is an unstable equilibrium.
Since the absolute value of potential energy holds no physical meaning, its zero value can be chosen as per...
Since the absolute value of potential energy holds no physical meaning, its zero value can be chosen as per...
4.2K