Monoclinic EuSn${}_2$As${}_2$: A Novel High-Pressure Network Structure

Abstract

The layered crystal of EuSn${}_2$As${}_2$ has a Bi${}_2$Te${}_3$-type structure in rhombohedral ($R\bar{3}m$) symmetry and has been confirmed to be an intrinsic magnetic topological insulator at ambient conditions. Combining {\it ab initio} calculations and \emph{in-situ} x-ray diffraction measurements, we identify a new monoclinic EuSn${}_2$As${}_2$ structure in $C2/m$ symmetry above $\sim$14 GPa. It has a three-dimensional network made up of honeycomb-like Sn sheets and zigzag As chains, transformed from the layered EuSn${}_2$As${}_2$ via a two-stage reconstruction mechanism with the connecting of Sn-Sn and As-As atoms successively between the buckled SnAs layers. Its dynamic structural stability has been verified by phonon mode analysis. Electrical resistance measurements reveal an insulator-metal-superconductor transition at low temperature around 5 and 15 GPa, respectively, according to the structural conversion, and the superconductivity with a \textit{T}${}_{\mathrm{C}}$ value of $\sim 4$ K is observed up to 30.8 GPa. These results establish a high-pressure EuSn${}_2$As${}_2$ phase with intriguing structural and electronic properties and expand our understandings about the layered magnetic topological insulators.

References in corpus (26)

• Topological Insulators
• Topological insulators and superconductors
• Restoring the density-gradient expansion for exchange in solids and surfaces
• Generalized gradient approximation for solids and their surfaces
• $Z_2$ Topological Order and the Quantum Spin Hall Effect
• Superconducting proximity effect and Majorana fermions at the surface of a topological insulator
• Topological Insulators with Inversion Symmetry
• Experimental Observation of the Quantum Anomalous Hall Effect in a Magnetic Topological Insulator
• Magnetic-field-induced quantized anomalous Hall effect in intrinsic magnetic topological insulator MnBi${}_2$Te${}_4$
• Topological axion states in magnetic insulator MnBi${}_2$Te${}_4$ with the quantized magnetoelectric effect
• Antiferromagnetic topological insulators
• Unique thickness-dependent properties of the van der Waals interlayer antiferromagnet $\mathrm{MnB}{\mathrm{i}}_2\mathrm{T}{\mathrm{e}}_4$ films
• Chiral Topological Superconductor From the Quantum Hall State
• Higher-order Topology of Axion Insulator EuIn${}_2$As${}_2$
• Superconductivity emerging from suppressed large magnetoresistant state in WTe2
• Pressure induced Superconductivity in Topological Compound Bi2Te3
• Dirac surface states in intrinsic magnetic topological insulators EuSn2As2 and MnBi2nTe3n+1
• Pressure-Induced Unconventional Superconducting Phase in the Topological Insulator Bi2Se3
• Superconductivity in Topological Insulator Sb2Te3 Induced by Pressure
• Magnetically Controllable Topological Quantum Phase Transitions in Antiferromagnetic Topological Insulator MnBi${}_2$Te${}_4$
• Superconductivity of topological insulator Bi2Se3 at high pressures
• Phase Diagram of Pressure-induced Superconductivity and its Relation to Hall Coefficient in Bi2Te3 Single Crystal
• Pressure-induced phase transition of Bi2Te3 into the bcc structure
• Topological phase transition in layered magnetic compound MnSb2Te4: Spin-orbit coupling and interlayer coupling dependeces
• Pressure-induced changes in the magnetic and valence state of EuFe2As2
• Phase Diagram of Pressure-Induced Superconductivity in EuFe2As2 Probed by High-Pressure Resistivity up to 3.2 GPa

Cited by in corpus (3)

• Intrinsic Magnetic Topological Materials
• Various magnetism of the compressed antiferromagnetic topological insulator EuSn2As2
• Thermal and mechanical properties and the structural phase transition under pressure in $A$In${}_2$As${}_2$ ($A$ = Ca, Sr, Ba)