Fate of Pomeranchuk effect in ultrahigh magnetic fields
- Naofumi Matsuyama
- So Yokomori
- Toshihiro Nomura
- Yuto Ishii
- Hiroaki Hayashi
- Hajime Ishikawa
- Kazuki Matsui
- Hatsumi Mori
- Koichi Kindo
- Yasuhiro H. Matsuda
- Shusaku Imajo
2026-01-12
The Pomeranchuk effect is a counterintuitive phenomenon where liquid helium-3 ( 3 He) solidifies under specific pressures, not when cooled, but when heated. This behaviour originates from the magnetic entropy of nuclear spins, suggesting a magnetic field should influence it. However, its detailed response to magnetic fields remains elusive due to the small nuclear magneton of 3 He and lack of analogous fermion systems. Here, we show that an electron system also exhibit the Pomeranchuk effect, where the Fermi liquid state solidifies in a high magnetic field, unlike conventional electron systems where a field melts an electron solid into a metal. Remarkably, the electron system displays a reentrant liquid state in ultrahigh fields. These responses are explained by changes in magnetic entropy and magnetisation, extending the underlying physics to 3 He. Our findings clarify magnetic-field impact on the Pomeranchuk effect and open avenues for magnetic control of chemical interactions.