Regensburg 2022 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 12: Correlated Electrons: Materials
TT 12.11: Vortrag
Dienstag, 6. September 2022, 12:15–12:30, H22
Magnon excitations, spin-lattice coupling and the emerging anisotropic nature of short-range order in van-der-Waals ferromagnets — M. Jonak1, J. Arneth1, A. Elghandour1, E. Waldendy1, S. Spachmann1, C. Koo1, M. Abdel-Hafiez2, S. Selter3, S. Aswartham3, and •Rüdiger Klingeler1 — 1Kirchhoff Institute for Physics, Heidelberg University, Germany — 2Dep. of Physics & Astronomy, Uppsala University, Sweden — 3IFW Dresden, Germany
CrI3 and Cr2Ge2Te6 are quasi-2D semiconducting van der Waals ferromagnets which evolve long-range order down to the single- or double-layer limit. Quantitative determination of magnetic anisotropy and spin-lattice coupling are crucial to further exploit these materials. We report ferromagnetic resonance studies in a broad frequency regime of 30 - 330 GHz and in magnetic fields up to 18 T and high-resolution capacitance dilatometry. Our data prove significant magnetoelastic coupling and provide quantitative values of the uniaxial pressure effects. Modelling the magnon branches in CrI3 by means of a domain-based ferromagnetic resonance model provides the microscopic parameters such the anisotropy gap of 80 GHz at 2 K which remarkably remains finite at TC and vanishes only above 80 K. In addition, we detect short-range magnetic correlations up to at least 160 K. Notably, the nature of the short-range correlations in CrI3 changes, confirming the importance of spin-orbit coupling for the evolution of long-range ferromagnetism which develops from magnetically anisotropic short-range order.