Dresden 2026 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 25: f-Electron Systems

TT 25.10: Vortrag

Dienstag, 10. März 2026, 12:00–12:15, HSZ/0101

Single crystal growth and characterization of EuMn₂Si₂ and EuMn₂Ge₂ — •Janina Strahl¹, Tom Gerntke^1,2, Kristin Kliemt¹, Kurt Kummer², and Cornelius Krellner¹ — ¹Institute of Physics, Goethe-University, Frankfurt (Main), Germany — ²European Synchrotron Radiation Facility (ESRF), F-38043 Grenoble Cedex, France

EuMn₂Si₂ exhibits a thermally driven valence transition of the europium ions from Eu³⁺ at low temperatures to Eu^2.5+ at high temperatures [1]. The isoelectronic and isostructural substitution of silicon with germanium leads to a stabilization of the divalent state of Eu in EuMn₂Ge₂ with reported ferromagnetic Eu ordering below 13 K [2]. Both rare earth intermetallic 122 compounds crystallize in the tetragonal ThCr₂Si₂ structure type and show antiferromagnetic ordering of the manganese sublattices above room temperature. In literature [1,2], additional Mn spin-reorientation transitions in polycrystalline EuMn₂Si₂ samples at low temperatures were observed. In this contribution, we present the single crystal growth and physical properties of both compounds. We found antiferromagnetic ordering of the Eu ions in single crystalline EuMn₂Ge₂ below 10.4 K. Furthermore, there is evidence that previously reported Mn reorientation transitions are absent in pure EuMn₂Si₂ single crystals, and a valence crossover occurs between 350-530 K.
[1] M. Hofmann et al., Phys. Rev. B 69, 174432 (2004)
[2] I. Nowik et al., Phys. Rev. B 55, 3033 (1997)