Topological insulators from the perspective of first‐principles calculations

Zhang, Haijun; Zhang, Shou-Cheng

doi:10.1002/pssr.201206414

Cited by 75 publications

(59 citation statements)

References 84 publications

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“…However, an sp-type band inversion [37], like in HgTe, exists in many I-III-VI 2 and II-IV-V 2 chalcopyrite compounds, which can give rise to topologically nontrivial state [35]. Notably, as the chalcopyrite structure is effectively similar to a strained zincblende structure, those chalcopyrite compounds with the nontrivial band inversion are expected to realize topological insulators or ideal Weyl semimetals, depending on the type of the effective strain [16].…”

Section: Electronic Structuresmentioning

confidence: 99%

Ideal Weyl Semimetals in the ChalcopyritesCuTlSe2,AgTlTe2,
Ruan
¹
,
Jian
²
,
Zhang
³

et al. 2016
Phys. Rev. Lett.
Self Cite

133

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Weyl semimetals are new states of matter which feature novel Fermi arcs and exotic transport phenomena. Based on first-principles calculations, we report that the chalcopyrites CuTlSe2, AgTlTe2, AuTlTe2 and ZnPbAs2 are ideal Weyl semimetals, having largely separated Weyl points (∼ 0.05Å −1 ) and uncovered Fermi arcs that are amenable to experimental detections. We also construct a minimal effective model to capture the low-energy physics of this class of Weyl semimetals. Our discovery is a major step toward a perfect playground of intriguing Weyl semimetals and potential applications for low-power and high-speed electronics.Weyl fermions, originally introduced as massless chiral fermions, are described by the Weyl equation [1]. Even though a number of elementary particles were considered as candidates of Weyl fermions, conclusive evidences of Weyl fermions as elementary particles are still lacking. Weyl fermions were also proposed as emergent low-energy quasiparticles in condensed matter systems breaking either time-reversal or spatial-inversion symmetry [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. One hallmark of Weyl semimetals is the existence of Fermi arcs in surface states [3]. So far the only experimentally known Weyl semimetals are the TaAs-class compounds, in which two sets of inequivalent Weyl points away from the Fermi level and complex Fermi surfaces were found by ARPES experiments [17][18][19]. Experimental evidences of negative magnetoresistance [2,20] induced by the chiral anomaly were also reported [21][22][23][24][25][26]. However, definite signatures of the chiral anomaly in the quantum limit, such as the linear-B negative magnetoresistance [2,20,27] and the emergent supersymmetry [28], and others [29][30][31][32] haven't been experimentally observed in known Weyl semimetals, which is partly due to the facts that the Weyl points are not all at the Fermi level and that there are coexisting trivial Fermi pockets. Therefore, it is urgent to discover ideal Weyl semimetals with only symmetry-related Weyl points at the Fermi level.In this work, we focus on a large family of ternary chalcopyrites ABC 2 at stoichiometry, which were of great interest because of potential applications including the thermoelectric effect, non-linear optics and solar cells [33,34]. Recently, some ternary chalcopyrites were predicted to be topological insulators [35]. Here, our first-principles calculations find that the chalcopyrite compounds CuTlSe 2 , AgTlTe 2 , AuTlTe 2 and ZnPbAs 2 are a class of ideal Weyl semimetals having eight symmetry-related Weyl points exactly at the Fermi level, but without any fine tuning. CuTlTe 2 and ZnPbSb 2 are also Weyl semimetals having eight symmetry-related Weyl points in energy gaps but have a few coexisting trivial bands around the X point; consequently they are not ideal Weyl semimetals at stoichiometry but can be tuned to be ideal Weyl semimetals by gating or doping. The ideal Weyl semimetals predicted in the chalcopyrites are analogous to those in compressively strained Hg...

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Section: Electronic Structuresmentioning

confidence: 99%

Ideal Weyl Semimetals in the ChalcopyritesCuTlSe2,AgTlTe2,
Ruan
¹
,
Jian
²
,
Zhang
³

et al. 2016
Phys. Rev. Lett.
Self Cite

133

View full text Add to dashboard Cite

show abstract

“…Many of the material realization of these TQSs are firstly predicted by theoretical calculations and then confirmed by experimental observations. 7,28 The bulkboundary correspondence of the topological matters is well known now and it is one of the most unique properties of them. For example, 2D TI is expected to host quantum spin Hall effect (QSHE) with 1D helical edge states, namely the electrons in such edge states have opposite velocities in opposite spin channels.…”

Section: Introductionmentioning

confidence: 99%

Large-gap two-dimensional topological insulator in oxygen functionalized MXene

Weng¹,

Ranjbar²,

Liang³

et al. 2015

Phys. Rev. B

257

193

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Two-dimensional (2D) topological insulator (TI) have been recognized as a new class of quantum state of matter. They are distinguished from normal 2D insulators with their nontrivial bandstructure topology identified by the Z 2 number as protected by time-reversal symmetry (TRS).2D TIs have intriguing spin-velocity locked conducting edge states and insulating properties in the bulk. In the edge states, the electrons with opposite spins propagate in opposite directions and the backscattering is fully prohibited when the TRS is conserved. This leads to quantized dissipationless "two-lane highway" for charge and spin transportation and promises potential applications. Up to now, only very few 2D systems have been discovered to possess this property. The lack of suitable material obstructs the further study and application. Here, by using first-principles calculations, we propose that the functionalized MXene with oxygen, M 2 CO 2 (M=W, Mo and Cr), are 2D TIs with the largest gap of 0.194 eV in W case. They are dynamically stable and natively antioxidant. Most importantly, they are very likely to be easily synthesized by recent developed selective chemical etching of transition-metal carbides (MAX phase). This will pave the way to tremendous applications of 2D TIs, such as "ideal" conducting wire, multifunctional spintronic device, and the realization of topological superconductivity and Majorana modes for quantum computing.2

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“…Topological insulators (TIs) [1][2][3][4] promise an avenue to realize fascinating applications such as dissipationless transport, spintronics, optoelectronics, thermoelectronics, fault-tolerant quantum computing, and efficient power transition [5][6][7][8][9][10][11][12][13][14]. This is due to their unique surface states that are topologically protected and thus robust against non-magnetic impurities and disorders.…”

Section: Introductionmentioning

confidence: 99%

Topological insulators in the ordered double transition metalsM2′M″C2MXenes (M′<

et al. 2016

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The family of two-dimensional transition metal carbides, so called MXenes, has recently found new members with ordered double transition metals M ′ 2 M ′′ C 2 , where M ′ and M ′′ stand for transition metals. Here, using a set of first-principles calculations, we demonstrate that some of the newly added members, oxide M ′ and M ′′ , while the band inversion occurs at the Γ point among the degenerate d x 2 −y 2 /d xy orbitals and a non-degenerate d 3z 2 −r 2 orbital, which is driven by the hybridization of the neighboring orbitals. The phonon dispersion calculations find that the predicted topological insulators are structurally stable. The predicted W-based MXenes with large band gaps might be suitable candidates for many topological applications at room temperature. In addition, we study the electronic structures of thicker ordered double transition metals M Zr, Hf) and find that they are nontrivial topological semimetals. Among the predicted topological insulators and topological semimetals, Mo 2 TiC 2 and Mo 2 Ti 2 C 3 functionalized with mixture of F, O, and OH have already been synthesized, and therefore some of the topological materials proposed here can be experimentally accessed.

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Topological insulators from the perspective of first‐principles calculations

Cited by 75 publications

References 84 publications

Ideal Weyl Semimetals in the ChalcopyritesCuTlSe2,AgTlTe2,
Ruan
¹
,
Jian
²
,
Zhang
³

et al. 2016
Phys. Rev. Lett.
Self Cite

Ideal Weyl Semimetals in the ChalcopyritesCuTlSe2,AgTlTe2,
Ruan
¹
,
Jian
²
,
Zhang
³

et al. 2016
Phys. Rev. Lett.
Self Cite

Large-gap two-dimensional topological insulator in oxygen functionalized MXene

Topological insulators in the ordered double transition metalsM2′M″C2MXenes (M′<

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Topological insulators from the perspective of first‐principles calculations

Cited by 75 publications

References 84 publications

Ideal Weyl Semimetals in the ChalcopyritesCuTlSe2,AgTlTe2,Ruan1, Jian2, Zhang3 et al. 2016Phys. Rev. Lett.Self Cite

Ideal Weyl Semimetals in the ChalcopyritesCuTlSe2,AgTlTe2,Ruan1, Jian2, Zhang3 et al. 2016Phys. Rev. Lett.Self Cite

Large-gap two-dimensional topological insulator in oxygen functionalized MXene

Topological insulators in the ordered double transition metalsM2′M″C2MXenes (M′<

Contact Info

Product

Resources

About

Ideal Weyl Semimetals in the ChalcopyritesCuTlSe2,AgTlTe2,
Ruan
¹
,
Jian
²
,
Zhang
³

et al. 2016
Phys. Rev. Lett.
Self Cite

Ideal Weyl Semimetals in the ChalcopyritesCuTlSe2,AgTlTe2,
Ruan
¹
,
Jian
²
,
Zhang
³

et al. 2016
Phys. Rev. Lett.
Self Cite