Preprint

Emergent Polar Metal Phase in a Van der Waals Mott Magnet

Shiyu DengCavendish Laboratory , University of Cambridge , J.J. Thomson Avenue , Cambridge , CB3 0HE , UKMatthew CoakSchool of Physics and Astronomy , University of Birmingham , Edgbaston , Birmingham B15 2TT , United KingdomCharles R. S. HainesPhysics , University of East Anglia , Norwich NR4 7TJ , United KingdomH. HamidovNavoi State University of Mining and Technologies , 72 M. Tarobiy Street , Navoi 210100 , UzbekistanGiulio LamprontiDepartment of Earth Sciences , University of Cambridge , Downing Street , Cambridge CB2 3EQ , United KingdomDavid M. JarvisInstitut Laue-Langevin , 71 Avenue des Martyrs , 38000 Grenoble , FranceXiaotian ZhangCavendish Laboratory , University of Cambridge , J.J. Thomson Avenue , Cambridge , CB3 0HE , UKCheng LiuCavendish Laboratory , University of Cambridge , J.J. Thomson Avenue , Cambridge , CB3 0HE , UKDominik DaisenbergerDiamond Light Source , Harwell Science and Innovation Campus , Didcot , OX11 0DE , United KingdomMark R. WarrenDiamond Light Source , Harwell Science and Innovation Campus , Didcot , OX11 0DE , United KingdomThomas HansenInstitut Laue-Langevin , 71 Avenue des Martyrs , 38000 Grenoble , FranceStefan KlotzInstitut Parisien de Chimie MoléculaireChaebin KimDepartment of Physics and Astronomy , Seoul National University , Seoul 08826 , Republic of KoreaPengtao YangBeijing National Laboratory for Condensed Matter Physics andBosen WangBeijing National Laboratory for Condensed Matter Physics andJinguang ChengBeijing National Laboratory for Condensed Matter Physics andJe-Geun ParkDepartment of Physics and Astronomy , Seoul National University , Seoul 08826 , Republic of KoreaAndrew WildesInstitute of Physics , Chinese Academy of Sciences , Beijing 100190 , ChinaSiddharth SaxenaBritish Management University Tashkent , 35 Mirza Bobur Street , Tashkent , Uzbekistan

2025en

ABI

Annotatsiya

We report the emergence of a two-dimensional (2D) polar metal phase in van der Waals compound FePSe$_3$ under moderate pressures. This layered material is a Mott insulator with antiferromagnetic order under ambient conditions. We show that FePSe$_3$ uniquely allows tuning a 2D correlated insulator into an exotic metal state where a loss of inversion symmetry leads to periodic polar displacements of ions, within a conducting phase - a polar metal. Our combined synchrotron and neutron diffraction data allow us to present a long-sought, unambiguous high-pressure structural model and show the polar displacements of this new phase. We also observe the suppression of magnetic ordering at the insulator-to-metal transition correspondent with this structural change. Our work outlines a comprehensive temperature-pressure phase diagram of FePSe$_3$, combining detailed structural, magnetic and transport data. The high-pressure phase exhibits activated semiconductor behavior at high temperatures, a $T^2$-dependence in its resistivity at lower temperatures - despite the conditions required for a `good metal' Fermi-Liquid description not being met in this case - and a low-temperature resistivity upturn which is suppressed as the system is tuned away from the concomitant transitions. The realisation of a tunable 2D polar metal state in FePSe$_3$ due to the loss of its inversion symmetry combined with pressure-induced metallicity offers a promising new platform to investigate this exotic phase at accessible pressures.

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Identifikatorlar

DOI: 10.48550/arxiv.2501.13635

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