Photocurrent in gyrotropic Weyl semimetals

Golub, L. E.; Ivchenko, E. L.; Spivak, B.

doi:10.1134/s0021364017120062

Cited by 45 publications

(45 citation statements)

References 15 publications

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“…III A, is the emergence of a 100 % chiral valley polarization when the magnetic field is applied along a direction without any particular symmetry. This finding anticipates large and magnetically tunable photogalvanic effects 15,36,37 in WSM.…”

Section: Application To Real Weyl Semimetalssupporting

confidence: 69%

Complete optical valley polarization in Weyl semimetals in strong magnetic fields

et al. 2019

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We present a theory of an optically induced valley polarization in an interacting, time-reversal symmetric Weyl semimetal placed under strong magnetic fields. Because the application of a magnetic field reduces the symmetry of the crystal, the optical absorption intensity differs at Weyl nodes that were equivalent by symmetry at zero field. At strong magnetic field, the difference in the absorption intensity reaches 100% for a sizeable frequency interval of the incident light. This complete valley polarization originates from interband transitions involving the chiral Landau level, and can be controlled by changing the directions of the magnetic field and the light propagation. We identify the splitting of 0 → 1 or −1 → 0 inter Landau level transitions as an observable signature of the complete valley polarization, and discuss its manifestation in the TaAs family of materials. arXiv:1906.02607v1 [cond-mat.mes-hall]

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Section: Application To Real Weyl Semimetalssupporting

confidence: 69%

Complete optical valley polarization in Weyl semimetals in strong magnetic fields

et al. 2019

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“…In the lower frequency range, where the indirect absorption takes place, the CPGE current density is determined by the light intensity, frequency, and fundamental constants . Under unpolarized excitation, the photocurrent is generated in the presence of magnetic field, where it is enhanced if one of the photocarriers is excited to or from the chiral magnetic subband in the quantizing magnetic field . A non‐universal photocurrent has been measured in TaAs where it flows perpendicular to both the light propagation direction and to the c ‐axis .…”

Section: Introductionmentioning

confidence: 99%

“…[3] Under unpolarized excitation, the photocurrent is generated in the presence of magnetic field, where it is enhanced if one of the photocarriers is excited to or from the chiral magnetic subband in the quantizing magnetic field. [6] A non-universal photocurrent has been measured in TaAs where it flows perpendicular to both the light propagation direction and to the c-axis. [7] The results of this experiment have been explained by Ma et al [7] by tilt of Weyl cones.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear Absorption and Photocurrent in Weyl Semimetals

Leppenen

Ivchenko

Golub

2019

Physica Status Solidi (b)

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A theory of light absorption and circular photocurrent in Weyl semimetals is developed for arbitrary large light intensities with account for both the elastic and inelastic relaxation processes of Weyl fermions. The direct optical transition rate is shown to saturate at large intensity, and the saturation behavior depends on the light polarization and on the ratio of the elastic and inelastic relaxation times. The linear‐circular dichroism in absorption is shown to exceed 10% at intermediate light wave amplitudes and fast energy relaxation. At large intensity I, the light absorption coefficient drops as 1/I, and the circular photogalvanic current increases as I.

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“…In gyrotropic crystal classes C nv (n = 3, 4, 6), the tensor γ has two nonzero components γ xy = −γ yx the calculation of which is the purpose of this work. The density of the circular photocurrent generated in Weyl semimetals under direct optical transitions is calculated according to the following formula [5,15,16]…”

Section: General Equations For the Photocurrentmentioning

confidence: 99%

“…[5] vanishes. In such crystals, the photocurrent summed over all the Weyl nodes is different from zero when taking into account the tilt [14] or nonlinear terms in the Hamiltonian (14) [15,16]. For definiteness, we consider the Weyl nodes with k z = 0.…”

Section: General Equations For the Photocurrentmentioning

confidence: 99%

Circular Photocurrent in Weyl Semimetals with Mirror Symmetry

Leppenen

Ivchenko

Golub

2019

J. Exp. Theor. Phys.

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We have studied theoretically the Weyl semimetals the point symmetry group of which has reflection planes and which contain equivalent valleys with opposite chiralities. These include the most frequently studied compounds, namely the transition metals monopnictides TaAs, NbAs, TaP, NbP, and also Bi1−xSbx alloys. The circular photogalvanic current, which inverts its direction under reversal of the light circular polarization, has been calculated for the light absorption under direct optical transitions near the Weyl points. In the studied materials, the total contribution of all the valleys to the photocurrent is nonzero only beyond the simple Weyl model, namely, if the effective electron Hamiltonian is extended to contain either an anisotropic spin-dependent linear contribution together with a spin-independent tilt or a spin-dependent contribution cubic in the electron wave vector k. With allowance for the tilt of the energy dispersion cone in a Weyl semimetal of the C4v symmetry, the photogalvanic current is expressed in terms of the components of the secondrank symmetric tensor that determines the energy spectrum of the carriers near the Weyl node; at low temperature, this contribution to the photocurrent is generated within a certain limited frequency range ∆. The photocurrent due to the cubic corrections, in the optical absorption region, is proportional to the light frequency squared and generated both inside and outside the ∆ window.

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Photocurrent in gyrotropic Weyl semimetals

Cited by 45 publications

References 15 publications

Complete optical valley polarization in Weyl semimetals in strong magnetic fields

Complete optical valley polarization in Weyl semimetals in strong magnetic fields

Nonlinear Absorption and Photocurrent in Weyl Semimetals

Circular Photocurrent in Weyl Semimetals with Mirror Symmetry

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