Employing first-principles based calculations, we reexamined the high-pressure phases of the vacancy-ordered iron-selenides, i.e. A2Fe4Se5 phase. A magnetic transition from the block-spin antiferromagnetic phase to Neel-AM phase is observed under high pressure when the iron-vacancy order is preserved. The transition is first-order, driven by the collapse of c-axis and accompanied by an insulator-metal transition. In addition, the Neel-AM phase is a rare example of intrinsic altermagnetism that does not require ligand atoms nor supercell construction to break the spatial inversion or translational symmetry between the two spin sublattices, with a spin-splitting of the band structure as large as 300 meV. If the re-entrant superconducting phase of KyFe2-xSe2 under high pressure emerges from the Neel-AM normal state, an equal-spin triplet pairing would be naturally favored.
@article{arxiv.2503.11228,
title = {Pressure Induced Altermagnetism in Layered Ternary Iron-Selenides},
author = {Zilong Li and Xin Ma and Siqi Wu and H. -Q. Yuan and Jianhui Dai and Chao Cao},
journal= {arXiv preprint arXiv:2503.11228},
year = {2025}
}