Tracing Dirac points of topological surface states by ferromagnetic resonance

Laura Pietanesi, Magdalena Marganska, Thomas Mayer, Michael Barth, Lin Chen, Ji Zou, Adrian Weindl, Alexander Liebig, Rebeca Díaz-Pardo, Dhavala Suri, Florian Schmid, Franz J. Gießibl, Klaus Richter, Yaroslav Tserkovnyak, Matthias Kronseder, Christian H. Back

Research output: Contribution to journalArticlepeer-review

Abstract

Ferromagnetic resonance is used to reveal features of the buried electronic band structure at interfaces between ferromagnetic metals and topological insulators. By monitoring the evolution of magnetic damping, the application of this method to a hybrid structure consisting of a ferromagnetic layer and a 3D topological insulator reveals a clear fingerprint of the Dirac point and exhibits additional features of the interfacial band structure not otherwise observable. The underlying spin-pumping mechanism is discussed in the framework of dissipation of angular momentum by topological surface states (TSSs). Tuning of the Fermi level within the TSS was verified both by varying the stoichiometry of the topological insulator layer and by electrostatic backgating and the damping values obtained in both cases show a remarkable agreement. The high-energy resolution of this method additionally allows us to resolve the energetic shift of the local Dirac points generated by local variations of the electrostatic potential. Calculations based on the chiral tunneling process naturally occurring in TSSs agree well with the experimental results.

Original languageEnglish
Article number064424
JournalPhysical Review B
Volume109
Issue number6
DOIs
StatePublished - 1 Feb 2024

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