Regensburg 2025 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 37: Correlated Electrons: Poster

TT 37.2: Poster

Mittwoch, 19. März 2025, 15:00–18:00, P4

Single Crystal Growth and Characterisation of EuMn₂Si₂ and EuMn₂Ge₂ — •Janina Strahl, Kristin Kliemt, and Cornelius Krellner — Institute of Physics, Goethe University, Frankfurt (Main), Germany

EuMn₂Si₂ exhibits a thermally driven valence transition at around 530 K 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 magnetic properties of both compounds. We found antiferromagnetic ordering of the Eu ions in single crystalline EuMn₂Ge₂ below 8.5 K and evidence that previously reported Mn reorientation transitions are absent in pure EuMn₂Si₂ single crystals.

[1] M. Hofmann et al., Phys. Rev. B 69, 174432 (2004)
[2] I. Nowik et al., Phys. Rev. B 55, 3033 (1997)