Tunable double-Weyl Fermion semimetal state in the SrSi2 materials class

Singh, Bahadur; Chang, Guoqing; Chang, Tay Rong; Huang, Shin-Ming; Su, Chenliang; Lin, Hsin; Bansil, Arun

doi:10.1038/s41598-018-28644-y

Cited by 46 publications

(33 citation statements)

References 63 publications

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“…For generalizations of Weyl bands with higher Chern numbers, [ 7,23,54,55,56,57 ] the shape of

σ_{1}^{IB} (ω)

depends on the band dispersion relations. In the so‐called multifold semimetals, where a few linear (rotationally symmetric) bands with generally different slopes cross at a given point of the BZ, [ 7,23 ] the optical conductivity is linear in frequency (up to the steps, related to the Pauli‐blocked transitions).…”

Section: Theoretical Background: Electronic Band Dispersion and Opticmentioning

confidence: 99%

Nodal Semimetals: A Survey on Optical Conductivity

Pronin

Dressel

2020

Physica Status Solidi (b)

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Among different topological and related phases of condensed matter, nodal semimetals occupy a special place -the electronic band topology in these materials is related to three-dimensional bulk, rather than to surface, states. A great variety of different realizations of electronic band crossings (the nodes) leads to a plethora of different electronic properties, ranging from the chiral anomaly to solid-state realizations of a black-hole horizon. The different nodal phases have similar low-energy band structure and quasiparticle dynamics, which both can be accessed experimentally by a number of methods. Optical measurements with their large penetration depth and high energy resolution are ideally suited as such a bulk probe; especially at low energies where other spectroscopic methods often lack the required resolution. In this contribution, we review recent optical-conductivity studies of different nodal semimetals, discuss possible limitations of such measurements, and provide a comparison between the experimental results, simple theoretical models, and band-structure-based calculations.

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“…For generalizations of Weyl bands with higher Chern numbers, [ 7,23,54,55,56,57 ] the shape of

σ_{1}^{IB} (ω)

Section: Theoretical Background: Electronic Band Dispersion and Opticmentioning

confidence: 99%

Nodal Semimetals: A Survey on Optical Conductivity

Pronin

Dressel

2020

Physica Status Solidi (b)

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“…The double-WSM state has been theoretically predicted recently in non-centrosymmetric SrSi 2 [53,54]. More importantly, it has been shown considering a time reversal symmetry invariant WSM lattice model that quantization in CPGE is substantially different from a time reversal broken WSM [55].…”

Section: Introductionmentioning

confidence: 84%

Electronic structure and unconventional non-linear response in double Weyl semimetal SrSi$_2$

Sadhukhan,

Nag

2021

Preprint

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Considering a non-centrosymmetric, non-magnetic double Weyl semimetal (WSM) SrSi2, we study the structural handedness of the material and correlate it with the distinct surface Fermi surface profile at two opposite surfaces. By investigating the electron and hole pockets in bulk Fermi surface behavior, we characterize the material as a type-I WSM. A finite energy separation between Weyl nodes of opposite chirality in SrSi2 allows us compute circular photogalvanic effect (CPGE). Followed by the three band formula, we show that CPGE is only quantized for Fermi level chosen in the vicinity of Weyl node having higher energy. Surprisingly, for the other Weyl node of opposite chirality in the lower energy, CPGE is not found to be quantized. Such a behavior of CPGE is in complete contrast to the time reversal breaking WSM where CPGE is quantized to two opposite plateau depending on the topological charge of the activated Weyl node. We further analyze our finding by examining the momentum resolved CPGE. Finally we show that two band formula for CPGE is not able to capture the quantization that is apprehended by the three band formula.

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“…It would be especially interesting to see both the magnetic and pseudomagnetic sound dichroism by flipping the direction of the sound propagation with respect to the field, as well as to observe the reduction of the attenuation coefficient for the sound propagating along the field. As possible material candidates, transition metal monopnictides TaAs, TaP, NbAs, and NbP [4], the magnetic compound EuCd 2 As 2 [69,70], and SrSi 2 [56,57] could be used. The magnetic material EuCd 2 As 2 is a promising candidate for the investigation of the pseudomagnetic sound dichroism since it breaks the time-reversal symmetry and contains only a single pair of Weyl nodes.…”

Section: Summary and Discussionmentioning

confidence: 99%

“…where ǫ α = ǫ α (p α ) is the energy dispersion in the absence of deformations at the node α and b 0 quantifies the separation between the Weyl nodes in energy space. For example, the Weyl nodes of opposite chiralities are located at different energies in SrSi 2 [56,57]. In the case of the effective Hamiltonian given in Eq.…”

Section: A Model Of Weyl Semimetalmentioning

confidence: 99%

Anomalous sound attenuation in Weyl semimetals in magnetic and pseudomagnetic fields

Sukhachov,

Glazman

2021

Preprint

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We evaluate the sound attenuation in a Weyl semimetal subject to a magnetic field or a pseudomagnetic field associated with a strain. Due to the interplay of intra-and inter-node scattering processes as well as screening, the fields generically reduce the sound absorption. A nontrivial dependence on the relative direction of the magnetic field and the sound wave vector, i.e., the magnetic sound dichroism, can occur in materials with non-symmetric Weyl nodes (e.g., different Fermi velocities and/or relaxation times). It is found that the sound dichroism in Weyl materials can be also activated by an external strain-induced pseudomagnetic field. In view of the dependence on the field direction, the dichroism may lead to a weak enhancement of the sound attenuation compared to its value at vanishing fields.

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Tunable double-Weyl Fermion semimetal state in the SrSi2 materials class

Cited by 46 publications

References 63 publications

Nodal Semimetals: A Survey on Optical Conductivity

Nodal Semimetals: A Survey on Optical Conductivity

Electronic structure and unconventional non-linear response in double Weyl semimetal SrSi$_2$

Anomalous sound attenuation in Weyl semimetals in magnetic and pseudomagnetic fields

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