2025/01/15 by Mori, Yuichiro, Aoki, Katsutoshi, Takano, Masahiro +7
#FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci)
paper · doi:10.48550/arxiv.2501.08937
Hydrogen incorporation into iron interstitial sites under high-pressure conditions forms iron hydride with a double hexagonal close-packed (dhcp) structure. This phase is stable over a broad pressure-temperature range and exhibits a pressure-induced ferromagnetic-paramagnetic transition. In this study, we revealed that dhcp iron hydride exhibits the Invar-like behaviour and its thermal expansion becomes negative at elevated pressures by X-ray diffraction. Our findings, supported by DFT+DMFT calculations, demonstrate that these anomalous volume changes are governed by magnetic transitions. Notably, the experimentally determined magnetic volume contribution is an order of magnitude smaller than previous theoretical predictions.