Electronic structure of the candidate 2D Dirac semimetal SrMnSb2: a  combined experimental and theoretical study

Ramankutty, S.V.; Henke, Jans; Schiphorst, Adriaan; Nutakki, Rajah; Bron, Stephan; Araizi-Kanoutas, Georgios; Mishra, Shrawan; Li, Lei; Huang, Yingkai; Kim, T. K.; Hoesch, Moritz; Schlueter, Christoph; Lee, Tien‐Lin; Visser, A. de; Zhong, Zhicheng; Wezel, Jasper van; Heumen, E. van; Golden, M. S.

doi:10.21468/scipostphys.4.2.010

Cited by 40 publications

(44 citation statements)

References 40 publications

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“…Such control can potentially be realized in materials in which magnetic order coexists with non-trivial electronic band topology. Recent ARPES, quantum oscillation, neutron diffraction and ab initio band structure studies suggest that materials in the AMnSb 2 (A = Ca, Sr, Ba, Eu, Yb) family display many of the required properties [9][10][11][12][13][14][15][16][17][18] . The two-dimensional zig-zag layer of Sb atoms [ Fig.…”

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confidence: 99%

Magnetic and electronic structure of Dirac semimetal candidate EuMnSb2

et al. 2019

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We report an experimental study of the magnetic order and electronic structure and transport of the layered pnictide EuMnSb2, performed using neutron diffraction, angle-resolved photoemission spectroscopy (ARPES), and magnetotransport measurements. We find that the Eu and Mn sublattices display antiferromagnetic (AFM) order below T Eu N = 21(1) K and T Mn N = 350(2) K respectively. The former can be described by an A-type AFM structure with the Eu spins aligned along the c axis (an in-plane direction), whereas the latter has a C-type AFM structure with Mn moments along the a-axis (perpendicular to the layers). The ARPES spectra reveal Dirac-like linearly dispersing bands near the Fermi energy. Furthermore, our magnetotransport measurements show strongly anisotropic magnetoresistance, and indicate that the Eu sublattice is intimately coupled to conduction electron states near the Dirac point. 75.30.Gw, 74.70.Xa Topological semimetals can host quasiparticle excitations which masquerade as massless fermions due to the linearly-dispersing electronic bands created by interactions with the crystal lattice. The Dirac or Weyl nodes, where the conduction and valence bands meet in momentum space, are robust against small perturbations due to the protection afforded by crystalline symmetries or the topology of the electronic bands 1-5 . Topological semimetals exhibit exceptional electronic transport properties (e.g. extremely high carrier mobility and large linear magnetoresistance) and the control of these exotic charge carriers could help realize a new generation of spintronic devices with low power consumption 6-8 .Such control can potentially be realized in materials in which magnetic order coexists with non-trivial electronic band topology. Recent ARPES, quantum oscillation, neutron diffraction and ab initio band structure studies suggest that materials in the AMnSb 2 (A = Ca, Sr, Ba, Eu, Yb) family display many of the required properties 9-18 . The two-dimensional zig-zag layer of Sb atoms [ Fig. 1] in these 112-pnictides play host to fermions which can be described by the relativistic Dirac or Weyl equations. Furthermore, the electronic transport in this family of materials also displays large magnetoresistive effects, suggesting a coupling between the magnetism and charge carriers 9-17 . These effects could be driven by changes in the electronic band structure topology due to changes in the symmetry of the spin structures induced by the applied field 19 .Within the AMnSb 2 family, EuMnSb 2 is of particular interest because the conducting zig-zag layer of Sb atoms is sandwiched between two interpenetrating magnetic sublattices (Eu and Mn), as shown in Fig. 1(a). Such a structure may lead to an enhancement of the coupling between the topological quasiparticles and mag-netism, compared to that in compounds with a nonmagnetic atom on the A site. The dramatic magnetoresistive behaviour observed in a recent work 20 is evidence for the importance of this coupling. Up to now, however, the nature of the magnetic order in...

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Magnetic and electronic structure of Dirac semimetal candidate EuMnSb2

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“…The nontrivial topological semimetal behavior was further supported by optical conductivity and ultrafast optical pump-probe measurements [4]. Nevertheless, Ramankutty et al [5] reported zero Berry phase indicative of trivial topology in nearly stoichiometric SrMnSb 2 . Previous density functional theory (DFT) calculations [5][6][7] showed that the lattice distortion in the orthorhombic structure prevents the formation of the Dirac points near the Fermi level by opening a gap.…”

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confidence: 90%

“…Nevertheless, Ramankutty et al [5] reported zero Berry phase indicative of trivial topology in nearly stoichiometric SrMnSb 2 . Previous density functional theory (DFT) calculations [5][6][7] showed that the lattice distortion in the orthorhombic structure prevents the formation of the Dirac points near the Fermi level by opening a gap. Both results cannot account for the observed topological semimetallic behavior reported in Ref.…”

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confidence: 99%

“…Now we turn to the low-temperature electronic property using the structural information at 5 K. We computed the total energy of several magnetic configurations using the low-temperature structure at 5 K. We found it is robust that the in-plane (out-of-plane) exchange is AFM (FM) and the single ion anisotropy is uniaxial [22], which indicates that the CAFM a state is most stable, and the FM b is metastable at 5 K. It is insightful to examine the electronic band structures of the PM, the CAFM a and the FM b states, as shown in Figure 4(c), (d), and (e), respectively. Because of the non-symmorphic symmetry, Dirac cones are expected at the Y and the T points [5,23] (X and M points in the notation of Ref. [5]).…”

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Influence of magnetism on Dirac semimetallic behavior in nonstoichiometric Sr1−yMn1−zSb2(y
Zhang
¹
,
Okamoto
²
,
Stone
³

et al. 2019
Phys. Rev. B
13
5
17
0
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Nonstoichiometric Sr1−yMn1−zSb2 (y, z <0.1) is known to exhibit a coexistence of magnetic order and the nontrivial semimetallic behavior related to Dirac or Weyl fermions. Here, we report inelastic neutron scattering analyses of the spin dynamics and density functional theory studies on the electronic properties of Sr1−yMn1−zSb2. We observe a relatively large spin excitation gap ≈ 8.5 meV at 5 K, and the interlayer magnetic exchange constant only 2.8 % of the dominant intralayer magnetic interaction, providing evidence that Sr1−yMn1−zSb2 exhibits a quasi-2D magnetism. Using density functional theory, we find a strong influence of magnetic orders on the electronic band structure and the Dirac dispersions near the Fermi level along the Y-S direction in the presence of a ferromagnetic ordering. Our study unveils novel interplay between the magnetic order, magnetic transition, and electronic property in Sr1−yMn1−zSb2, and opens new pathways to control the relativistic band structure through magnetism in ternary compounds.Topological semimetals [1, 2] are a newly emerged frontier in condensed matter physics and have stimulated tremendous research interest because they give access to new quantum phenomena and are very attractive for both fundamental research and technological application. Particular attention has focused on Weyl or Dirac semimetals that exibit a coexistence with magnetism as a promising route to modify and control Weyl/Dirac fermions, electronic transport properties and band topology, among which SrMnSb 2 has attracted much interest recently. Liu et al.[3] reported a nontrivial semimetallic behavior related to Dirac or Weyl fermions including nearly massless quasiparticles with a π Berry phase coupled to ferromagnetism in nonstoichiometric Sr 1−y Mn 1−z Sb 2 . For the magnetic behavior, it displays ferromagnetic (FM) order below T C ∼ 565 K, followed by a transition to canted antiferromagnetic (AFM) order with a net FM component below T F M −AF M ≈ 304 K [3]. The nontrivial topological semimetal behavior was further supported by optical conductivity and ultrafast optical pump-probe measurements [4]. Nevertheless, Ramankutty et al.[5] reported zero Berry phase indicative of trivial topology in nearly stoichiometric SrMnSb 2 . Previous density functional theory (DFT) calculations [5][6][7] showed that the lattice distortion in the orthorhombic structure prevents the formation of the Dirac points near the Fermi level by opening a gap. Both results cannot account for the observed topological semimetallic behavior reported in Ref.[3]. It is therefore challenging to explore whether there are indeed Dirac/Weyl points in proximity to the Fermi level and what drives their formation in Sr 1−y Mn 1−z Sb 2 . Furthermore, SrMnSb 2 offers a wonderful opportunity to address an important question whether there is a close correlation between magnetic order and band topology in 3D Dirac compounds.In addition to SrMnSb 2 , other Alkaline earth ternary AMnC 2 "112" compounds (A =Sr, Ca, Ba, C= Bi or Sb) [8][9][10][11][12]...

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“…It should be noted that, recent ARPES, transport measurements, and density functional theory (DFT) and tight binding calculations show that the electronic bands are gapped above the Fermi energy for SrMnSb 2 , suggesting trivial topology [21]. The extracted Berry phase is zero, indicating the non-topological character of the transport in SrMnSb 2 [21], whereas the non-trivial π Berry phase was observed in Type A crystals in Ref. [20].…”

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confidence: 95%

Crystal growth, microstructure, and physical properties of SrMnSb2

Liu

Zhou

et al. 2019

Phys. Rev. B

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We report on the crystal and magnetic structures, magnetic, and transport properties of SrMnSb2 single crystals grown by the self-flux method. Magnetic susceptibility measurements reveal an antiferromagnetic (AFM) transition at TN = 295(3) K. Above TN, the susceptibility slightly increases and forms a broad peak at T ∼ 420 K, which is a typical feature of two-dimensional magnetic systems. Neutron diffraction measurements on single crystals confirm the previously reported C-type AFM structure below TN. Both de Haas-van Alphen (dHvA) and Shubnikov-de Haas (SdH) effects are observed in SrMnSb2 single crystals. Analysis of the oscillatory component by a Fourier transform shows that the prominent frequencies obtained by the two different techniques are practically the same within error regardless of sample size or saturated magnetic moment. Transmission electron microscopy (TEM) reveals the existence of stacking faults in the crystals, which result from a horizontal shift of Sb atomic layers suggesting possible ordering of Sb vacancies in the crystals. Increase of temperature in susceptibility measurements leads to the formation of a strong peak at T ∼ 570 K that upon cooling under magnetic field the susceptibility shows a ferromagnetic transition at TC ∼ 580 K. Neutron powder diffraction on crushed single-crystals does not support an FM phase above TN. Furthermore, X-ray magnetic circular dichroism (XMCD) measurements of a single crystal at the L2,3 edge of Mn shows a signal due to induced canting of AFM moments by the applied magnetic field. All evidence strongly suggests that a chemical transformation at the surface of single crystals occurs above 500 K concurrently producing a minute amount of ferromagnetic impurity phase. * yongliu31@outlook.com † vaknin@ameslab.gov arXiv:1902.04948v1 [cond-mat.mtrl-sci]

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Electronic structure of the candidate 2D Dirac semimetal SrMnSb2: a combined experimental and theoretical study

Cited by 40 publications

References 40 publications

Magnetic and electronic structure of Dirac semimetal candidate EuMnSb2

Magnetic and electronic structure of Dirac semimetal candidate EuMnSb2

Influence of magnetism on Dirac semimetallic behavior in nonstoichiometric Sr1−yMn1−zSb2(y
Zhang
¹
,
Okamoto
²
,
Stone
³

et al. 2019
Phys. Rev. B
13
5
17
0
View full text Add to dashboard Cite

Crystal growth, microstructure, and physical properties of SrMnSb2

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Electronic structure of the candidate 2D Dirac semimetal SrMnSb2: a combined experimental and theoretical study

Cited by 40 publications

References 40 publications

Magnetic and electronic structure of Dirac semimetal candidate EuMnSb2

Magnetic and electronic structure of Dirac semimetal candidate EuMnSb2

Influence of magnetism on Dirac semimetallic behavior in nonstoichiometric Sr1−yMn1−zSb2(yZhang1, Okamoto2, Stone3 et al. 2019Phys. Rev. B135170View full textAdd to dashboardCite

Crystal growth, microstructure, and physical properties of SrMnSb2

Contact Info

Product

Resources

About

Influence of magnetism on Dirac semimetallic behavior in nonstoichiometric Sr1−yMn1−zSb2(y
Zhang
¹
,
Okamoto
²
,
Stone
³

et al. 2019
Phys. Rev. B
13
5
17
0
View full text Add to dashboard Cite