Excitonic collective modes in Weyl semimetals

Srivatsa, N. S.; Ganesh, R.

doi:10.1103/physrevb.98.165133

Cited by 6 publications

(3 citation statements)

References 47 publications

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“…We then obtain the ground-state phase diagram for the WSM model, as a function of the tilt parameter w z , and find that the critical value of the tilt at which the system undergoes a transition from the type-I to the type-II WSM phase is renormalized in the presence of interactions. Spin density-wave instabilities have also appeared in previous studies on type-I and type-II WSM models, using different methods [43,44,50,51,54,78,79], primarily analytical.…”

Section: Discussionmentioning

confidence: 89%

Spin density wave order in interacting type-I and type-II Weyl semimetals

Kundu,

Sénéchal

2020

Preprint

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Weyl semimetals (WSMs), featuring massless linearly dispersing chiral fermions in three dimensions, provide an excellent platform for studying the interplay of electronic interactions and topology, and exploring new correlated states of matter. Here, we examine the effect of a local repulsive interaction on an inversion-symmetry breaking Weyl semimetal model, using Cluster Dynamical Mean Field theory (CDMFT) and Variational Cluster Approximation (VCA) methods. Our analysis reveals a continuous transition from the gapless Weyl semimetal phase to a gapped spin density wave (SDW) ordered phase at a critical value of the interaction, which is determined by the band structure parameters. Further, we introduce a finite tilt in the linear dispersion and examine the corresponding behavior for a type-II Weyl semimetal model, where the critical interaction strength is found to be significantly diminished, indicating a greater susceptibility towards interactions. The behavior of different physical quantities, such as the double occupancy, the spectral function and the Berry curvature associated with the Weyl nodes are obtained in both the semimetallic and the magnetically ordered states. Finally, we provide an interaction-induced phase diagram for the Weyl semimetal model, as a function of the tilt parameter.

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Section: Discussionmentioning

confidence: 89%

Spin density wave order in interacting type-I and type-II Weyl semimetals

Kundu,

Sénéchal

2020

Preprint

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“…It is an interesting problem in many-particle systems to study some novel collective modes. [13][14][15][16][17] In contrast to the Coulomb interaction among electrons in metals or semi-conductors, the S-wave interaction among ultracold atoms can be modulated by the technique of Feshbach resonance. [18,19] The low-energy S-wave interaction in ultracold atomic gases is determined by the scattering length a s .…”

Section: Introductionmentioning

confidence: 99%

Collective modes of Weyl fermions with repulsive S-wave interaction*

Wang

Zhang

et al. 2020

Chinese Phys. B

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We calculate the spin and density susceptibility of Weyl fermions with repulsive S-wave interaction in ultracold gases. Weyl fermions have a linear dispersion, which is qualitatively different from the parabolic dispersion of conventional materials. We find that there are different collective modes for the different strengths of repulsive interaction by solving the poles equations of the susceptibility in the random-phase approximation. In the long-wavelength limit, the sound velocity and the energy gaps vary with the different strengths of the interaction in the zero sound mode and the gapped modes, respectively. The particle–hole continuum is obtained as well, where the imaginary part of the susceptibility is nonzero.

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“…It turns out Weyl semimetals naturally have an axion term that is related to the separation in k-space and in energy of the Weyl nodes. What's more, when the Weyl system undergoes lattice translation symmetry breaking due to the emergence of charge density wave (CDW) order [14,15], the collective motion associated to the phase of the CDW in turn leads to a dynamical axion effect and to a nonlinear magnetoelectric effect on top of the response due to band structure effects [16][17][18][19]. In the presence of uncompensated carrier densities this may even lead to spatially inhomogeneous textures due to softening of the axionic collective mode [20].…”

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confidence: 99%

Multiphoton Spectroscopy of a Dynamical Axion Insulator

Narang

Olivia

Curtis

et al. 2023

Preprint

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The unusual magnetoelectric transport present in Weyl semimetals can be compactly understood as manifestations of an underlying axion field, which itself is determined by the microscopic band structure. The axion couples nonlinearly to electric and magnetic fields and possesses a signature topological magnetoelectric response, leading to a modified form of Maxwell’s equations known as axion electrodynamics. Axions are naturally present in Weyl semimetals relating to the separation of the Weyl nodes in energy and in crystal momentum. In the presence of strong interactions, charge density-wave (CDW) order may develop which serves to gap the Weyl nodes and introduces corresponding collective excitations. When the inherent chiral symmetry of Weyl semimetals is spontaneously broken by the formation of CDW order, the resultant chiral condensate is endowed with intrinsic dynamics which yields a dynamical contribution to the axion field. However, unambiguous identification of this dynamical axion mode is challenging due to its inherent nonlinear coupling to electromagnetic fields. Therefore, we propose an all-optical protocol for verifying and characterizing dynamical axion collective modes in Weyl semimetals with CDW order. First, we show that axion collective mode can be excited using two-photon excitation schemes. Following excitation, the collective axion oscillations are then diagnosed by measuring the time-resolved Kerr rotation. Our results demonstrate a pathway towards utilizing multi-photon and entangled pair spectroscopies to identify new correlated phases in quantum matter.

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Excitonic collective modes in Weyl semimetals

Cited by 6 publications

References 47 publications

Spin density wave order in interacting type-I and type-II Weyl semimetals

Spin density wave order in interacting type-I and type-II Weyl semimetals

Collective modes of Weyl fermions with repulsive S-wave interaction*

Multiphoton Spectroscopy of a Dynamical Axion Insulator

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