Spin dynamics of a magnetic Weyl semimetal Sr${}_{1-x}$Mn${}_{1-y}$Sb${}_2$

Abstract

Dirac matters provide a platform for exploring the interplay of their carriers with other quantum phenomena. Sr${}_{1-x}$Mn${}_{1-y}$Sb${}_2$ has been proposed to be a magnetic Weyl semimetal and provides an excellent platform to study the coupling between Weyl fermions and magnons. Here, we report comprehensive inelastic neutron scattering (INS) measurements on single crystals of Sr${}_{1-x}$Mn${}_{1-y}$Sb${}_2$, which have been well characterized by magnetization and magnetotransport measurements, both of which demonstrate that the material is a topologically nontrivial semimetal. The INS spectra clearly show a spin gap of $\sim 6$ meV. The dispersion in the magnetic Mn layer extends up to about 76 meV, while that between the layers has a narrow band width of 6 meV. We find that the linear spin-wave theory using a Heisenberg spin Hamiltonian can reproduce the experimental spectra with the following parameters: a nearest-neighbor ($S{J}_1\sim 28.0$ meV) and next-nearest-neighbor in-plane exchange interaction ($S{J}_2\sim 9.3$ meV) , interlayer exchange coupling ($S{J}_c\sim -0.1$ meV), and spin anisotropy constant ($SD\sim -0.07$ meV). Despite the coexistence of Weyl fermions and magnons, we find no clear evidence that the magnetic dynamics are influenced by the Weyl fermions in Sr${}_{1-x}$Mn${}_{1-y}$Sb${}_2$, possibly because that the Weyl fermions and magnons reside in the Sb and Mn layers separately, and the interlayer coupling is weak due to the quasi-two-dimensional nature of the material, as also evident from the small $S{J}_c$ of -0.1 meV.

arXiv comment12 pages, 4 figures

References in corpus (57)

• The electronic properties of graphene
• Experimental Observation of Quantum Hall Effect and Berry's Phase in Graphene
• Electronic Structure of Pyrochlore Iridates: From Topological Dirac Metal to Mott Insulator
• Weyl and Dirac Semimetals in Three Dimensional Solids
• Discovery of a Weyl Fermion Semimetal and Topological Fermi Arcs
• Topological Insulator Materials
• Ultrahigh mobility and giant magnetoresistance in the Dirac semimetal Cd${}_3$As${}_2$
• Weyl semimetal phase in non-centrosymmetric transition metal monophosphides
• Giant anomalous Hall effect in a ferromagnetic Kagome-lattice semimetal
• Extremely large magnetoresistance and ultrahigh mobility in the topological Weyl semimetal NbP
• Observation of Weyl nodes in TaAs
• Observation of the chiral magnetic effect in ZrTe5
• Dirac materials
• Magnetic Weyl Semimetal Phase in a Kagome Crystal
• Fermi-arc diversity on surface terminations of the magnetic Weyl semimetal Co3Sn2S2
• Large intrinsic anomalous Hall effect in half-metallic ferromagnet Co3Sn2S2 with magnetic Weyl fermions
• Dirac Fermions in Solids - from High Tc cuprates and Graphene to Topological Insulators and Weyl Semimetals
• Linear spin wave theory for single-Q incommensurate magnetic structures
• Discovery of topological Weyl fermion lines and drumhead surface states in a room temperature magnet
• Quantum transport evidence for a three-dimensional Dirac semimetal phase in Cd3As2
• Linear magnetoresistance caused by mobility fluctuations in the n-doped Cd3As2
• Large nonsaturating magnetoresistance and signature of non-degenerate Dirac nodes in ZrSiS
• Anisotropic Dirac fermions in a Bi square net of SrMnBi2
• Topological surface Fermi arcs in the magnetic Weyl semimetal Co${}_3$Sn${}_2$S${}_2$
• Quantum Hall effect in a bulk antiferromagnet EuMnBi${}_2$ with magnetically confined two-dimensional Dirac fermions
• Helicity protected ultrahigh mobility Weyl fermions in NbP
• Spin fluctuation induced Weyl semimetal state in the paramagnetic phase of EuCd${}_2$As${}_2$
• A magnetic topological semimetal Sr1-yMn1-zSb2 (y, z< 0.1)
• Itinerant magnetic excitations in antiferromagnetic CaFe2As2
• Topological Semimetals in Square-Net Materials
• Quantum transport of two-dimensional Dirac fermions in SrMnBi2
• Two dimensional Dirac fermions and quantum magnetoresistance in CaMnBi${}_2$
• Anisotropic Fermi Surface and Quantum Limit Transport in High Mobility 3D Dirac Semimetal Cd3As2
• Anisotropic Dirac electronic structures of AMnBi${}_2$ (A=Sr, Ca)
• Effect of Eu magnetism on the electronic properties of the candidate Dirac material EuMnBi2
• Coupling of magnetic order to planar Bi electrons in the anisotropic Dirac metals AMnBi2 (A = Sr, Ca)
• Nontrivial Berry phase in magnetic BaMnSb2 semimetal
• Nearly massless Dirac fermions hosted by Sb square net in BaMnSb2
• Itinerant Spin Excitations in SrFe2As2 Measured by Inelastic Neutron Scattering
• Magnetic Excitations in Non-Collinear Antiferromagnetic Weyl Semimetal $\mathsf{M}{\mathsf{n}}_3\mathsf{Sn}$
• Quantum Oscillations and Coherent Interlayer Transport in a New Topological Dirac Semimetal Candidate: YbMnSb${}_2$
• Interplay of Dirac electrons and magnetism in AMnBi2 (A=Ca, Sr)
• Electron-hole asymmetry, Dirac fermions, and quantum magnetoresistance in BaMnBi2
• Observation of two-dimensional Fermi surface and Dirac dispersion in YbMnSb${}_2$
• Electrodynamic response of type II Weyl semimetals
• Unusual interlayer quantum transport behavior caused by the zeroth Landau level in YbMnBi2
• An optical investigation of the strong spin-orbital coupled magnetic semimetal YbMnBi${}_2$
• Evidence for a Dirac nodal-line semimetal in SrAs${}_3$
• Large linear magnetoresistance in a new Dirac material BaMnBi2
• Impact of antiferromagnetic order on Landau level splitting of quasi-two-dimensional Dirac fermions in EuMnBi${}_2$
• Electronic structure of the candidate 2D Dirac semimetal SrMnSb2: a combined experimental and theoretical study
• Observation of well-defined quasi-particle over a wide energy range in quasi-2D system
• Magnetic structure and excitations of the topological semimetal YbMnBi${}_2$
• Crystal growth, microstructure and physical properties of SrMnSb${}_2$
• Spindynamics in the antiferromagnetic phases of the Dirac metals $A$MnBi${}_2$ ($A=$ Sr, Ca)
• Signatures of coupling between spin waves and Dirac fermions in YbMnBi${}_2$
• Quasi-2D magnetism and origin of the Dirac semimetallic behavior in nonstoichiometric Sr${}_{1-y}$Mn${}_{1-z}$Sb${}_2$ (y, z~$<$0.1)

Cited by in corpus (6)

• Neutron spectroscopy evidence on the dual nature of magnetic excitations in a van der Waals metallic ferromagnet Fe${}_{2.72}$GeTe${}_2$
• Electronic structure and topology across $T_c$ in magnetic Weyl semimetal Co${}_3$Sn${}_2$S${}_2$
• Topological Signatures in Nodal Semimetals through Neutron Scattering
• Coupling of magnetism and Dirac fermions in YbMnSb2
• Crystalline electric field excitations in Weyl semimetal \textit{R}AlSi (\textit{R} = Ce, Pr and Nd)
• Spin waves in Dirac semimetal Ca${}_{0.6}$Sr${}_{0.4}$MnSb${}_2$ investigated with neutrons by the diffraction method