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Séminaire Théorie : mercredi 10 juillet 2024 à 11h00

Julia Hannukainen (KTH Stockholm)

Titre : The axial anomaly in magnetic Weyl semimetals

LPMMC, Salle G421


Résumé : In this talk I introduce the chiral anomaly in the context of magnetic Weyl semimetals with domain walls. Weyl semimetals serve as a platform to explore the chiral anomaly—the nonconservation of chiral charge due to applied parallel electric and magnetic, and/or parallel axial electric and axial magnetic, fields. Axial electromagnetic fields are emergent fields which couple with opposite sign to fermions with opposite chirality. We consider a magnetic Weyl semimetal which contains two Weyl fermions of opposite chirality separated in momentum space. Introducing a dynamic domain wall in the Weyl node separation generates axial electromagnetic fields, leading to the chiral anomaly. Via the chiral magnetic effect, the anomaly generates a current, resulting in electromagnetic radiation, which if detected, measures the axial anomaly. In reverse, the anomaly influences the domain wall dynamics, enabling electric control of the chirality of domain walls and improving the domain wall dynamics. Measuring the electric field mediated changes in the domain wall chirality would constitute a direct proof of the chiral anomaly.

Refs: Hannukainen, Ferreiros, Cortijo, Bardarson, Phys. Rev. B 102, 241401(R) (2020), Hannukainen, Bardarson, Cortijo, Ferreiros ,SciPost Phys. 10, 102 (2021)