Berlin 2024 – scientific programme

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MA: Fachverband Magnetismus

MA 46: Poster II

MA 46.19: Poster

Thursday, March 21, 2024, 15:00–18:00, Poster C

Dilatometry studies on van der Waals ferromagnets Fe_3−δGeTe₂, CrI₃ and Cr₂Ge₂Te₆ — •Erik Walendy¹, Sven Sprachmann¹, Eva Brücher², Rheinhard Kremer², and Rüdiger Klingeler¹ — ¹Kirchhoff Institute for Physics, Heidelberg University, Germany — ²Max Planck Institute for Solid State Research, Stuttgart, Germany

The van der Waals materials Fe_3−δGeTe₂, Cr₂Ge₂Te₆ and CrI₃ develop long-range ferromagnetic order down to the monolayer. In the bulk, long-range magnetic order appears at about 220 K, 65 K and 61 K respectively. Our high-resolution capacitance dilatometry studies imply significant magneto-elastic coupling as demonstrated by pronounced anomalies in thermal expansion and magnetostriction. We determine the uniaxial pressure dependencies of T_C and of the dominant energy scales by means of Grüneisen scaling. In Cr₂ Ge₂ Te₆, the magnetic phase diagram is determined and extremely large uniaxial pressure dependencies are observed. In CrI₃, in addition to the response of the ferromagnetic bulk phase, we find magnetostrictive signatures of the antiferromagnetic surface phase. The comparison of the three materials provides further insight into the relevance of spin-orbit coupling for the development of long-range magnetic order in quasi-2D van der Waals materials.

Keywords: Dilatometry; 2D ferromagnets; van der Waals materials