Berlin 2018 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 68: Topological Insulators and Weyl Semimetals (joint session MA/TT)

TT 68.8: Vortrag

Mittwoch, 14. März 2018, 17:00–17:15, EB 407

Topological jumps in a finite-size Dzyaloshinskii-Moriya antiferromagnetic chain — •Jaroslav Chovan^1,2 and Dominik Legut¹ — ¹IT4Innovations National Supercomputing Center VSB - Technical University Ostrava, CZ 708 33 Ostrava, Czech Republic — ²Department of Physics, Matej Bel University, Banska Bystrica, Slovakia

Recently, experiments with thin films of chiral ferromagnets MnSi and CrNbS₆ observed sudden jumps in magnetoresistence and/or magnetization induced by a magnetic field applied perpendicularly to the chiral axis. Subsequent theory traced the origin of these jumps to a field-induced transitions between topological sectors with different number of magnetic solitons and established the importance of boundary conditions. Here, we explore the topic in the context of a two-sublattice antiferromagnet. We thus carry out a detailed calculation of magnetic properties of a finite Heisenberg antiferromagnetic chain with Dzyaloshinskii-Moriya interactions in the presence of external magnetic field. By comparing the energies of magnetic solitons from different topological sectors, we calculate the ground state dependence on the chain size N and the field H. We construct a phase diagram and analyze the topological jumps between the individual sectors in detail and discuss ambiguity in counting the number of magnetic solitons for even-number spin chain. Our results may guide future experiments.

This work was supported by Czech Science Foundation grant No. 17-27790S, project No. CZ.02.1.01/0.0/0.0/16_013/0001791, and Slovak Grant VEGA No. 1/0269/17.