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TT: Fachverband Tiefe Temperaturen

TT 18: Skyrmions (joint session TT/MA)

TT 18.8: Vortrag

Montag, 16. März 2020, 18:00–18:15, HSZ 304

Skyrmion Lattice Magnet Gd₂PdSi₃ Studied by High-Resolution Dilatometry — •Sven Spachmann¹, Matthias Frontzek², Chongde Cao³, Wolfgang Löser⁴, and Rüdiger Klingeler¹ — ¹Kirchhoff Institute for Physics, Heidelberg, Germany — ²Oak Ridge National Laboratory, Oak Ridge, USA — ³Northwestern Polytechnical University, Xi’an, China — ⁴Leibniz Institute for Solid State and Materials Research (IFW), Dresden, Germany

A Bloch-type skyrmion state emerging in low magnetic fields has recently been reported for the frustrated centrosymmetric triangular-lattice magnet Gd₂PdSi₃ [1]. Here, we present high-resolution thermal expansion and magnetostriction measurements on single crystals of this material in order to study the phase diagram and in particular the transitions to the skyrmion phase. In zero magnetic field, a single peak in the thermal expansion coefficient indicates the onset of long-range antiferromagnetic order at T_N=19.7 K, which exhibits uniaxial pressure dependencies of opposite sign along the a- and c-axis, respectively. Up to B=4 T, four known phases are confirmed, including the skyrmion phase for B||c which appears in a discontinuous transition. In addition, a previously non-reported phase is observed. The anomalies in thermal expansion and magnetostriction at the different phase boundaries as well as the respective uniaxial pressure dependencies imply significant changes in the spin-lattice coupling for different fields.

[1] T. Kurumaji et al., Science 10.1126/science.aau0968 (2019)