Magnetic Control of Soft Chiral Phonons in PbTe
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- Rice University, Houston, TX (United States)
- University of Sao Paulo (Brazil)
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Instituto Nacional de Pesquisas Espaciais, Sao Paulo (Brazil)
- Yokohama National University (Japan)
- Tohoku University, Sendai (Japan)
- Northeastern University, Boston, MA (United States); Massachusetts Institute of Technology (MIT), Cambridge, MA (United States)
We report PbTe crystals have a soft transverse optical phonon mode in the terahertz frequency range, which is known to efficiently decay into heat-carrying acoustic phonons, resulting in anomalously low thermal conductivity. Here, we studied this phonon via polarization-dependent terahertz spectroscopy. We observed softening of this mode with decreasing temperature, indicative of incipient ferroelectricity, which we explain through a model including strong anharmonicity with a quartic displacement term. In magnetic fields up to 25 T, the phonon mode splits into two modes with opposite handedness, exhibiting circular dichroism. Their frequencies display Zeeman splitting together with an overall diamagnetic shift with increasing magnetic field. Using a group-theoretical approach, we demonstrate that these observations are the result of magnetic field-induced morphic changes in the crystal symmetries through the Lorentz force exerted on the lattice ions. Thus, our Letter reveals a novel process of controlling phonon properties in a soft ionic lattice by a strong magnetic field.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA); USDOE Laboratory Directed Research and Development (LDRD) Program; National Science Foundation (NSF); Brasil@Rice Collaborative; Sao Paulo Research Foundation (FAPESP); National Council for Scientific and Technological Development (CNPq); USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division; Japan Society for the Promotion of Science (JSPS)
- Grant/Contract Number:
- 89233218CNA000001
- OSTI ID:
- 1874190
- Report Number(s):
- LA-UR-21-26398
- Journal Information:
- Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 7 Vol. 128; ISSN 0031-9007
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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