1. Ferroelectricity by Bose–Einstein condensation in a quantum magnet
- Author
-
Masayuki Hagiwara, Y. Sawada, Hidekazu Tanaka, K. Watanabe, K. Kakihata, Masashige Matsumoto, and Shojiro Kimura
- Subjects
Josephson effect ,Science ,General Physics and Astronomy ,02 engineering and technology ,01 natural sciences ,Article ,General Biochemistry, Genetics and Molecular Biology ,law.invention ,Superfluidity ,Quantization (physics) ,law ,Quantum mechanics ,0103 physical sciences ,010306 general physics ,Quantum statistical mechanics ,Quantum ,Condensed Matter::Quantum Gases ,Physics ,Multidisciplinary ,Condensed matter physics ,Condensed Matter::Other ,Magnon ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter::Strongly Correlated Electrons ,0210 nano-technology ,Bose–Einstein condensate ,Identical particles - Abstract
The Bose–Einstein condensation is a fascinating phenomenon, which results from quantum statistics for identical particles with an integer spin. Surprising properties, such as superfluidity, vortex quantization or Josephson effect, appear owing to the macroscopic quantum coherence, which spontaneously develops in Bose–Einstein condensates. Realization of Bose–Einstein condensation is not restricted in fluids like liquid helium, a superconducting phase of paired electrons in a metal and laser-cooled dilute alkali atoms. Bosonic quasi-particles like exciton-polariton and magnon in solids-state systems can also undergo Bose–Einstein condensation in certain conditions. Here, we report that the quantum coherence in Bose–Einstein condensate of the magnon quasi particles yields spontaneous electric polarization in the quantum magnet TlCuCl3, leading to remarkable magnetoelectric effect. Very soft ferroelectricity is realized as a consequence of the O(2) symmetry breaking by magnon Bose–Einstein condensation. The finding of this ferroelectricity will open a new window to explore multi-functionality of quantum magnets., Magnons, quantized spin excitations in magnetic materials, may undergo Bose-Einstein condensation into a macroscopic correlated quantum state at low temperature. Here, the authors demonstrate how magnon condensation in quantum magnet TlCuCl3 generates an electrical polarization.
- Published
- 2016