GdAlSi: An antiferromagnetic topological Weyl semimetal with non-relativistic spin splitting

Abstract

Spintronics has emerged as a viable alternative to traditional electronics based technologies in the past few decades. While on one hand, the discovery of topological phases of matter with protected spin-polarized states has opened up exciting prospects, recent revelation of intriguing non-relativistic spin splitting in collinear antiferromagnetic materials with unique symmetries facilitate a wide possibility of realizing both these features simultaneously. In this work, we report the co-existence of these two intriguing properties within a single material: GdAlSi. It crystallizes in a body-centered tetragonal structure with a non-centrosymmetric space group $I{4}_{1}md$ ($109$), which is confirmed using detailed structural analysis through X-ray diffraction (XRD) and optical second harmonic generation (SHG) measurements. The magnetization data indicates AFM ordering with an ordering temperature ($T_N$) $\sim$ 32 K. Ab-initio calculations reveal GdAlSi to be a collinear antiferromagnetic Weyl semimetal with an unconventional, momentum-dependent spin splitting, also referred to as altermagnet. Angle-resolved photoemission spectroscopy measurements on GdAlSi single crystals subsequently confirm the presence of Fermi arcs, a distinctive hallmark of Weyl semimetals. Electric and magnetic multipole analysis provides a deeper understanding of the symmetry-mediated, momentum-dependent spin splitting, which has strictly non-relativistic origin. To the best of our knowledge, such co-existence of unconventional antiferromagnetic order and non-trivial topology is unprecedented and has never been observed before in a single material, rendering GdAlSi a special and promising candidate material. We propose a device harnessing these features, poised to enable practical and efficient topotronic applications.

24 pages (14 pages main, 10 pages supplement), 15 figures (7 figures main, 8 figures supplement)

References in corpus (17)

• Weyl semimetal phase in non-centrosymmetric transition metal monophosphides
• Altermagnetism: spin-momentum locked phase protected by non-relativistic symmetries
• Observation of spin splitting torque in a collinear antiferromagnet RuO2
• Observation of spin-splitter torque in collinear antiferromagnetic RuO${}_2$
• Antiferromagnetism in RuO${}_2$ as $d$-wave Pomeranchuk instability
• Bottom-up design of spin-split and reshaped electronic band structures in spin-orbit-coupling free antiferromagnets: Procedure on the basis of augmented multipoles
• Prediction of low-Z collinear and noncollinear antiferromagnetic compounds having momentum-dependent spin splitting even without spin-orbit coupling
• Topological Magnetic Phase in the Candidate Weyl Semimetal CeAlGe
• Magnetic octupoles as the order parameter for unconventional antiferromagnetism
• Observation of Weyl fermions in a magnetic non-centrosymmetric crystal
• Essential role of anisotropic magnetic dipole in anomalous Hall effect
• Ferrimagnetic Regulation of Weyl Fermions in a Noncentrosymmetric Magnetic Weyl Semimetal
• SHAARP: An Open-Source Package for Analytical and Numerical Modeling of Optical Second Harmonic Generation in Anisotropic Crystals
• Observation of Fermi arcs and Weyl nodes in a non-centrosymmetric magnetic Weyl semimetal
• Magnetic octupole tensor decomposition and second-order magnetoelectric effect
• Spin Conductivity Based on Magnetic Toroidal Quadrupole Hidden in Antiferromagnets
• Revealing hidden magneto-electric multipoles using Compton scattering

Cited by in corpus (9)

• Topological responses from gapped Weyl points in 2D altermagnets
• Pushing an Altermagnet to the Ultimate 2D Limit: Evidence of Symmetry Breaking in Monolayers of GdAlSi
• Designing Non-Relativistic Spin Splitting in Oxide Perovskites
• Weyl-mediated Ruderman-Kittel-Kasuya-Yosida interaction revisited: imaginary-time formalism and finite temperature effects
• Altermagnetism, ARPES, symmetry, non-relativistic band splitting
• Dirac edge states as signature of two-dimensional altermagnetic topological crystalline phase
• Crystalline electric field excitations in Weyl semimetal \textit{R}AlSi (\textit{R} = Ce, Pr and Nd)
• Correlated helimagnetic configuration in a nonsymmorphic magnetic nodal semimetal
• Quantum effects in the magnon spectrum of 2D altermagnets via continuous similarity transformations