Materials that break time-reversal or inversion symmetry possess nondegenerate electronic bands, which can touch at so-called Weyl points. The spinor eigenstates in the vicinity of a Weyl point exhibit a well-defined chirality ±1. Numerous works have studied the consequences of this chirality, for example, in unconventional magnetoelectric transport. However, even a Weyl point with isotropic dispersion is not only characterized by its chirality but also by the momentum dependence of the spinor eigenstates. For a single Weyl point, this momentum-space spin structure can be brought into standard “hedgehog” form by a unitary transformation, but for two or more Weyl points, this is not possible. In this work, we show that the relative spin structure of a pair of Weyl points has strong qualitative signatures in the electromagnetic response. Specifically, we investigate the Friedel oscillations in the induced charge density due to a test charge for a centrosymmetric system consisting of two Weyl points with isotropic dispersion. The most pronounced signature is that the amplitude of the Friedel oscillations falls off as 1/r4 in directions in which both Weyl points exhibit the same spin structure, while for directions with inverted spin structures, the amplitude of the Friedel oscillations decreases as 1/r3.
%0 Journal Article
%1 PhysRevB.109.035145
%A Knoll, Andy
%A Timm, Carsten
%D 2024
%I American Physical Society
%J Phys. Rev. B
%K a
%N 3
%P 035145
%R 10.1103/PhysRevB.109.035145
%T Irreducible momentum-space spin structure of Weyl semimetals and its signatures in Friedel oscillations
%U https://link.aps.org/doi/10.1103/PhysRevB.109.035145
%V 109
%X Materials that break time-reversal or inversion symmetry possess nondegenerate electronic bands, which can touch at so-called Weyl points. The spinor eigenstates in the vicinity of a Weyl point exhibit a well-defined chirality ±1. Numerous works have studied the consequences of this chirality, for example, in unconventional magnetoelectric transport. However, even a Weyl point with isotropic dispersion is not only characterized by its chirality but also by the momentum dependence of the spinor eigenstates. For a single Weyl point, this momentum-space spin structure can be brought into standard “hedgehog” form by a unitary transformation, but for two or more Weyl points, this is not possible. In this work, we show that the relative spin structure of a pair of Weyl points has strong qualitative signatures in the electromagnetic response. Specifically, we investigate the Friedel oscillations in the induced charge density due to a test charge for a centrosymmetric system consisting of two Weyl points with isotropic dispersion. The most pronounced signature is that the amplitude of the Friedel oscillations falls off as 1/r4 in directions in which both Weyl points exhibit the same spin structure, while for directions with inverted spin structures, the amplitude of the Friedel oscillations decreases as 1/r3.
@article{PhysRevB.109.035145,
abstract = {Materials that break time-reversal or inversion symmetry possess nondegenerate electronic bands, which can touch at so-called Weyl points. The spinor eigenstates in the vicinity of a Weyl point exhibit a well-defined chirality ±1. Numerous works have studied the consequences of this chirality, for example, in unconventional magnetoelectric transport. However, even a Weyl point with isotropic dispersion is not only characterized by its chirality but also by the momentum dependence of the spinor eigenstates. For a single Weyl point, this momentum-space spin structure can be brought into standard “hedgehog” form by a unitary transformation, but for two or more Weyl points, this is not possible. In this work, we show that the relative spin structure of a pair of Weyl points has strong qualitative signatures in the electromagnetic response. Specifically, we investigate the Friedel oscillations in the induced charge density due to a test charge for a centrosymmetric system consisting of two Weyl points with isotropic dispersion. The most pronounced signature is that the amplitude of the Friedel oscillations falls off as 1/r4 in directions in which both Weyl points exhibit the same spin structure, while for directions with inverted spin structures, the amplitude of the Friedel oscillations decreases as 1/r3.},
added-at = {2024-04-26T15:37:24.000+0200},
author = {Knoll, Andy and Timm, Carsten},
biburl = {https://www.bibsonomy.org/bibtex/2097a9bd66e6fc2f59705094692b27291/ctqmat},
day = 19,
doi = {10.1103/PhysRevB.109.035145},
interhash = {cd257be0666ff247c39910821c58c2c6},
intrahash = {097a9bd66e6fc2f59705094692b27291},
journal = {Phys. Rev. B},
keywords = {a},
month = {01},
number = 3,
numpages = {18},
pages = 035145,
publisher = {American Physical Society},
timestamp = {2024-04-26T15:37:24.000+0200},
title = {Irreducible momentum-space spin structure of Weyl semimetals and its signatures in Friedel oscillations},
url = {https://link.aps.org/doi/10.1103/PhysRevB.109.035145},
volume = 109,
year = 2024
}