RKKY Interactions in Two- and Four-Band Weyl Semimetals
ORAL
Abstract
Weyl semimetals (WSMs) have attracted significant attention due to their unique topological properties and distinct electronic structure [1]. The breaking of either time-reversal or inversion symmetries in WSMs leads to a separation of Dirac-like cones in the spectrum, resulting in the formation of pairs of chiral Weyl nodes located at different points in k-space. The presence of magnetic impurities in these systems gives rise to Ruderman-Kittel-Kasuya-Yosida (RKKY) and exchange interactions, which can mediated by both bulk Weyl fermions [2] as well as by electrons in surface states forming the so-called Fermi arcs [3]. As such, the RKKY interaction in WSMs is a multifaceted phenomenon, influenced by a variety of factors.
In this contribution, we derive analytical expressions for a specific class of systems that describe WSMs involving two and four bands, with up to four Weyl nodes. Going beyond the low-energy linear approximation and including the full band structure, our expressions reveal the emergence of both Heisenberg and Ising terms, as well as an additional Dzyaloshinsky-Moriya term in the absence of inversion symmetry. Moreover, our numerical calculations demonstrate a modulation of the typical RKKY oscillation pattern in different cases and how certain terms are forbidden by symmetries. More importantly, we highlight both qualitative and quantitative differences between calculations involving the full band structure and those restricted to the low-energy linear dispersion in the Weyl cones. This underscores the importance of going beyond the linear approximation to obtain accurate results.
[1] N. P. Armitage et al. Rev. Mod. Phys., 90 015001 (2018).
[2] M. V. Hosseini and M. Askari, Phys.Rev.B 92, 224435 (2015).
[3] S. Verma et al., Phys.Rev.B 101, 085419 (2020).
In this contribution, we derive analytical expressions for a specific class of systems that describe WSMs involving two and four bands, with up to four Weyl nodes. Going beyond the low-energy linear approximation and including the full band structure, our expressions reveal the emergence of both Heisenberg and Ising terms, as well as an additional Dzyaloshinsky-Moriya term in the absence of inversion symmetry. Moreover, our numerical calculations demonstrate a modulation of the typical RKKY oscillation pattern in different cases and how certain terms are forbidden by symmetries. More importantly, we highlight both qualitative and quantitative differences between calculations involving the full band structure and those restricted to the low-energy linear dispersion in the Weyl cones. This underscores the importance of going beyond the linear approximation to obtain accurate results.
[1] N. P. Armitage et al. Rev. Mod. Phys., 90 015001 (2018).
[2] M. V. Hosseini and M. Askari, Phys.Rev.B 92, 224435 (2015).
[3] S. Verma et al., Phys.Rev.B 101, 085419 (2020).
*We acknowledge financial support from CAPES, CNPq (309789/2020-6, 312622/2023-6), and FAPESP (2021/04078-0, 2022/15453-0).
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Presenters
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Luis G Dias Da Silva
- University of Sao Paulo