Pressure-Induced Structural and Magnetic Evolution in Layered Antiferromagnet YbMn$_2$Sb$_2$

TL;DR

This study investigates how applying pressure alters the structure, magnetism, and electronic properties of YbMn$_2$Sb$_2$, revealing a pressure-induced phase transition, magnetic evolution, and a semiconductor-metal transition supported by experimental and theoretical analysis.

Contribution

It provides the first detailed investigation of pressure effects on YbMn$_2$Sb$_2$, uncovering structural, magnetic, and electronic phase transitions and their underlying mechanisms.

Findings

Pressure induces a structural transition from trigonal to monoclinic phase.

Pressure suppresses resistance and induces metallic behavior beyond 5 GPa.

Neutron diffraction reveals an incommensurate magnetic structure under pressure.

Abstract

Electronic states under pressure exhibit unconventional spin and charge dynamics that provide a powerful route to uncover exotic phases in quantum materials. Here, we present the structural, magnetic, and electronic evolution of YbMn$_2$Sb$_2$ under pressure. Single-crystal X-ray diffraction reveals a pressure-induced structural transition from the space group trigonal $P\bar{3}m1$ to the monoclinic $P2_1$/$m$ phase near 3.5 GPa, which remains stable up to 10 GPa. Magnetization measurements display an anomalously weak net magnetic moment and the absence of Curie-Weiss behavior up to 400 K, suggesting the formation of short-range Mn moment pairs that cancel macroscopically and subsequently evolve into long-range order upon cooling. Temperature-dependent resistivity shows semiconducting behavior with a transition at ~119 K at ambient pressure, while pressure induces a dramatic suppression of resistance and the emergence of metallic-like temperature dependence, stabilized beyond 5 GPa. This pressure-driven semiconductor-metal transition is consistent with our density functional theory calculations, confirming the closing of the band gap under compression. Neutron diffraction under pressure identifies an incommensurate magnetic structure with antiparallel correlations between paired spins. Together, these results demonstrate how pressure-driven structural tuning and competing exchange interactions stabilize unconventional magnetic states in this low-dimensional magnetic semiconductor.