Evidence for a strain-tuned topological phase transition in ZrTe
            <sub>5</sub>

Mutch, Joshua; Chen, Wei-Chih; Went, Preston; Qian, Tiema; Wilson, Ilham Zaky; Andreev, A. V.; Chen, Cheng-Chien; Chu, Jiun‐Haw

doi:10.1126/sciadv.aav9771

Cited by 147 publications

(110 citation statements)

References 49 publications

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“…FeSe presents an excellent playground to explore the interplay of electronic nematicity and symmetry breaking strain due to its structural simplicity and the absence of magnetic ordering that is present in many other Fe-based superconductors 29,30 . In principle, various experimental methods can be used to apply strain to a material, such as voltage-controlled piezoelectric setups 11,13,25,31,32 , mechanical actuators 27 , differential thermal contraction 24,33 , and heteroepitaxial film growth [34][35][36][37] . In this work, we use molecular beam epitaxy (MBE) to grow FeSe thin films (a = 3.8 Å) on SrTiO 3 (001), a substrate with a~2% lattice mismatch (a = 3.9 Å) ( Fig.…”

Section: Resultsmentioning

confidence: 99%

Nanoscale decoupling of electronic nematicity and structural anisotropy in FeSe thin films

Ren

Zhao

et al. 2021

Nat Commun

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In a material prone to a nematic instability, anisotropic strain in principle provides a preferred symmetry-breaking direction for the electronic nematic state to follow. This is consistent with experimental observations, where electronic nematicity and structural anisotropy typically appear hand-in-hand. In this work, we discover that electronic nematicity can be locally decoupled from the underlying structural anisotropy in strain-engineered iron-selenide (FeSe) thin films. We use heteroepitaxial molecular beam epitaxy to grow FeSe with a nanoscale network of modulations that give rise to spatially varying strain. We map local anisotropic strain by analyzing scanning tunneling microscopy topographs, and visualize electronic nematic domains from concomitant spectroscopic maps. While the domains form so that the energy of nemato-elastic coupling is minimized, we observe distinct regions where electronic nematic ordering fails to flip direction, even though the underlying structural anisotropy is locally reversed. The findings point towards a nanometer-scale stiffness of the nematic order parameter.

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Section: Resultsmentioning

confidence: 99%

Nanoscale decoupling of electronic nematicity and structural anisotropy in FeSe thin films

Ren

Zhao

et al. 2021

Nat Commun

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“…(1), this requires a fine-tuning of Hamiltonian parameters to achieve a bulk gap closure. One possible yet experimentally challenging route is to tune the chemical compositions in materials such as Bi 2−x In x Se 3 , Pb 1−x Sn x Se, Pb 1−x Sn x Te, Bi 1−x Sb x , and Hg 1−x Cd x Se, for which the critical point corresponds to specific values of x. First-principles calculations have predicted that this type of Dirac semimetal should occur in the materials ZrTe 5 (53) and SrSn 2 As 2 (54), but its experimental verification has proven difficult (55,56,57,58) as a result of sensitivity to factors such as temperature, pressure, and composition homogeneity.…”

Section: Dirac Semimetalsmentioning

confidence: 99%

Topological Semimetals from First Principles

Gao

Venderbos

Kim

et al. 2019

Annu. Rev. Mater. Res.

215

118

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We review recent theoretical progress in the understanding and prediction of novel topological semimetals. Topological semimetals define a class of gapless electronic phases exhibiting topologically stable crossings of energy bands. Different types of topological semimetals can be distinguished based on the degeneracy of the band crossings, their codimension (e.g. point or line nodes), as well as the crystal space group symmetries on which the protection of stable band crossings relies. The dispersion near the band crossing is a further discriminating characteristic. These properties give rise to a wide range of distinct semimetal phases such as Dirac or Weyl semimetals, point or line node semimetals, and type-I or type-II semimetals. In this review we give a general description of various families of topological semimetals with an emphasis on proposed material realizations from first-principles calculations. The conceptual framework for studying topological gapless electronic phases is reviewed, with a particular focus on the symmetry requirements of energy band crossings, and the relation between the different families of topological semimetals is elucidated. In addition to the paradigmatic Dirac and Weyl semimetals, we pay particular attention to more recent examples of topological semimetals, which include nodal line semimetals, multifold fermion semimetals, triple-point semimetals. Less emphasis is placed on their surface state properties, responses to external probes, and recent experimental developments. 1 arXiv:1810.08186v1 [cond-mat.mes-hall]

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“…A powerful experimental tool for the exploration of the symmetry dependence of electronic properties is the application of uniaxial stress, as it allows to reduce the symmetry of the crystal lattice and thus provides a rather different kind of information than application of hydrostatic pressure. In recent years, the interest in topological properties of electronic band structures surged, which also aroused the interest in studying the uniaxial strain response of materials with remarkable topological band-structure features, using both theoretical [1][2][3][4][5][6][7][8][9][10][11][12] and experimental [13][14][15][16][17] methods.…”

Section: Introductionmentioning

confidence: 99%

Effect of uniaxial stress on the electronic band structure of NbP

et al. 2020

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The Weyl semimetal NbP exhibits a very small Fermi surface consisting of two electron and two hole pockets, whose fourfold degeneracy in k space is tied to the rotational symmetry of the underlying tetragonal crystal lattice. By applying uniaxial stress, the crystal symmetry can be reduced, which successively leads to a degeneracy lifting of the Fermi-surface pockets. This is reflected by a splitting of the Shubnikov-de Haas frequencies when the magnetic field is aligned along the c axis of the tetragonal lattice. In this study, we present the measurement of Shubnikovde Haas oscillations of single-crystalline NbP samples under uniaxial tension, combined with stateof-the-art calculations of the electronic band structure. Our results show qualitative agreement between calculated and experimentally determined Shubnikov-de Haas frequencies, demonstrating the robustness of the band-structure calculations upon introducing strain. Furthermore, we predict a significant shift of the Weyl points with increasing uniaxial tension, allowing for an effective tuning to the Fermi level at only 0.8 % of strain along the a axis.

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Evidence for a strain-tuned topological phase transition in ZrTe ₅

Cited by 147 publications

References 49 publications

Nanoscale decoupling of electronic nematicity and structural anisotropy in FeSe thin films

Nanoscale decoupling of electronic nematicity and structural anisotropy in FeSe thin films

Topological Semimetals from First Principles

Effect of uniaxial stress on the electronic band structure of NbP

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Evidence for a strain-tuned topological phase transition in ZrTe 5

Cited by 147 publications

References 49 publications

Nanoscale decoupling of electronic nematicity and structural anisotropy in FeSe thin films

Nanoscale decoupling of electronic nematicity and structural anisotropy in FeSe thin films

Topological Semimetals from First Principles

Effect of uniaxial stress on the electronic band structure of NbP

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Product

Resources

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Evidence for a strain-tuned topological phase transition in ZrTe ₅