Regensburg 2025 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 3: Correlated Magnetism – General
TT 3.10: Talk
Monday, March 17, 2025, 12:00–12:15, H32
Investigation of the magnetoelastic coupling in CaMn2P2 and SrMn2P2 — •Sven Graus, Ashiwini Balodhi, N. S. Sangeetha, Teslin R. Thomas, Maximilian van de Loo, Andreas Kreyssig, and Anna E. Böhmer — Experimentalphysik IV, Ruhr-Universität Bochum, 44801 Bochum, Germany
Mn-based 122-compounds exhibit complex magnetic ordering in the antiferromagnetic state. In contrast to other related materials CaMn2P2 shows a strong first-order and SrMn2P2 a weak first-order antiferromagnetic phase transition [1]. Since the antiferromagnetic ordering breaks the three-fold symmetry of the lattice, one expects lattice distortions, which we investigated by high-resolution thermal expansion measurements. Thermal-expansion data of CaMn2P2 show a significant decrease of the sample length upon entering the antiferromagnetic state. Applying different uniaxial pressures along the [1 1 0] and [1 -1 0] directions alters the transition in qualitatively distinct ways. Increasing uniaxial pressure shifts the transition temperature upwards which shows magnetoelastic coupling and is consistent with the interpretation of an orthorhombic lattice distortion in the antiferromagnetic phase. In SrMn2P2, an anomaly in the thermal expansion is clearly resolvable upon entering the antiferromagnetic state. From 300 K to 6 K the linear thermal expansion coefficient α continuously decreases, reaching negative values below ∼ 100 K.
We acknowledge support by the Deutsche Forschungsgemeinschaft (DFG) under CRC/TRR 288 (Project A02).
[1] Sangeetha et al., PNAS 118, e2108724118 (2021).
Keywords: capacitance dilatometry; thermal expansion; antiferromagnetism; phase transition; lattice distortion