Patterns of electromagnetic response in topological semimetals

Ramamurthy, Srinidhi T.; Hughes, Taylor L.

doi:10.1103/physrevb.92.085105

Cited by 70 publications

(93 citation statements)

References 96 publications

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“…The effective Lagrangian L T represents a 2+1-d quantum Hall response with a Hall conductance of 1, while L I represents a charge polarization and orbital magnetization response whose precise meaning was discussed in Ref. 7, and which we review in Sec. VII.…”

Section: Motivation and Overview Of Resultsmentioning

confidence: 99%

“…As mentioned above, the main goal of this paper is to construct a model of gapless bosons in 2+1-d which shares many of the properties of the minimal two-node DSM of free fermions studied, for example, in Ref. 7. The main properties we will be interested in are: (1) the electromagnetic response of the system to perturbations which break time-reversal or inversion symmetry, and (2) the perturbative stability of the gapless, low-energy effective theory.…”

Section: Motivation and Overview Of Resultsmentioning

confidence: 99%

“…VII we give an explicit construction of the BSM model using an array of coupled 1D wires. This construction is motivated by the fact that 2+1-d fermion DSMs can be constructed out of arrays of coupled wires 7 . A building block for the simplest two-node DSM of fermions is a wire with a single 1+1-d massless Dirac fermion.…”

Section: Motivation and Overview Of Resultsmentioning

confidence: 99%

“…Our review closely follows the discussion in Ref. 7, in which the electromagnetic responses of various topological semi-metals were derived. Specifically, we discuss a square lattice model of a DSM, its symmetry requirements, its low-energy description, the timereversal and inversion symmetry breaking electromagnetic responses of the system, and finally the local stability of the Dirac nodes.…”

Section: Review Of the Free-fermion Dirac Semi-metalmentioning

confidence: 99%

“…With these conditions the 2+1-d DSM forms a robust topological semi-metal phase. Interestingly, if we relax condition (ii) then the system will form a gapped insulator, but will typically have an unusual electromagnetic response (e.g., a quantum anomalous Hall effect 6 or a charge polarization 7 ).…”

Section: Introductionmentioning

confidence: 99%

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Bosonic analog of a topological Dirac semimetal: Effective theory, neighboring phases, and wire construction

2016

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We construct a bosonic analog of a two-dimensional topological Dirac Semi-Metal (DSM). The low-energy description of the most basic 2D DSM model consists of two Dirac cones at positions ±k0 in momentum space. The local stability of the Dirac cones is guaranteed by a composite symmetry Z T I 2 , where T is timereversal and I is inversion. This model also exhibits interesting time-reversal and inversion symmetry breaking electromagnetic responses. In this work we construct a bosonic version by replacing each Dirac cone with a copy of the O(4) Nonlinear Sigma Model (NLSM) with topological theta term and theta angle θ = ±π. One copy of this NLSM also describes the gapless surface termination of the 3D Bosonic Topological Insulator (BTI). We compute the time-reversal and inversion symmetry breaking electromagnetic responses for our model and show that they are twice the value one gets in the DSM case matching what one might expect from, for example, a bosonic Chern insulator. We also investigate the stability of the BSM model and find that the composite Z T I 2 symmetry again plays an important role. Along the way we clarify many aspects of the surface theory of the BTI including the electromagnetic response, the charges and statistics of vortex excitations, and the stability to symmetry-allowed perturbations. We briefly comment on the relation between the various descriptions of the O(4) NLSM with θ = π used in this paper (a dual vortex description and a description in terms of four massless fermions) and the recently proposed dual description of the BTI surface in terms of 2 + 1 dimensional Quantum Electrodynamics with two flavors of fermion (N = 2 QED3). In a set of four Appendixes we review some of the tools used in the paper, and also derive some of the more technical results.

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Section: Motivation and Overview Of Resultsmentioning

confidence: 99%

Section: Motivation and Overview Of Resultsmentioning

confidence: 99%

Section: Motivation and Overview Of Resultsmentioning

confidence: 99%

Section: Review Of the Free-fermion Dirac Semi-metalmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Bosonic analog of a topological Dirac semimetal: Effective theory, neighboring phases, and wire construction

2016

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Ultrafast Carrier Relaxation and Second Harmonic Generation in a Higher‐Fold Weyl Fermionic System PtAl

Saini,

Punjal,

Pandey

et al. 2023

Advanced Physics Research

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In topological materials, shielding of bulk and surface states by crystalline symmetries has provided hitherto unknown access to electronic states in condensed matter physics. Interestingly, photoexcited carriers relax on an ultrafast timescales, demonstrating large transient mobility that can be harnessed for the development of ultrafast optoelectronic devices. In addition, these devices are much more effective than topologically trivial systems because topological states are resilient to the corresponding symmetry‐invariant perturbations. By using optical pump probe measurements, the relaxation dynamics of a topologically nontrivial chiral single crystal, PtAl, is systematically described. Based on the experimental data on transient reflectivity and electronic structures, it is found that the carrier relaxation process involves both acoustic and optical phonons with oscillation frequencies of 0.06 and 2.94 THz, respectively, in picosecond time scale. PtAl with a space group of P213 allows only one non‐zero susceptibility element, i.e., d14, in second harmonic generation (SHG) with a large value of 468(1) pm V–1, which is significantly higher than that observed in standard GaAs(111) and ZnTe(110) crystals. The intensity dependence of the SHG signal in PtAl reveals a non‐perturbative origin. The present study on PtAl provides deeper insight into topological states that will be useful for ultrafast optoelectronic devices.

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Emergent gravity in the cubic tight-binding model of Weyl semimetal in the presence of elastic deformations

Cortijo

Zubkov

2016

Annals of Physics

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We consider the tight -binding model with cubic symmetry that may be relevant for the description of a certain class of Weyl semimetals. We take into account elastic deformations of the semimetal through the modification of hopping parameters. This modification results in the appearance of emergent gauge field and the coordinate dependent anisotropic Fermi velocity. The latter may be interpreted as emergent gravitational field. * zubkov@itep.ru 2

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Patterns of electromagnetic response in topological semimetals

Cited by 70 publications

References 96 publications

Bosonic analog of a topological Dirac semimetal: Effective theory, neighboring phases, and wire construction

Bosonic analog of a topological Dirac semimetal: Effective theory, neighboring phases, and wire construction

Ultrafast Carrier Relaxation and Second Harmonic Generation in a Higher‐Fold Weyl Fermionic System PtAl

Emergent gravity in the cubic tight-binding model of Weyl semimetal in the presence of elastic deformations

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