SKM 2021 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 9: INNOMAG e.V. Diploma/Master Prize (2021)

MA 9.4: Vortrag

Mittwoch, 29. September 2021, 13:30–13:50, H2

High-Resolution Dilatometry Studies on Transition Metal Oxides — •Marco Hoffmann, Kaustav Dey, Sven Spachmann, and Rüdiger Klingeler — Kirchhoff Institute for Physics, Heidelberg University, INF 227, D-69120 Heidelberg, Germany

The thermodynamic properties of the transition metal oxides CoTiO₃ and R₄Ni₃O₁₀ (R = La, Pr, Nd) were studied by means of high-resolution capacitance dilatometry. Thermal expansion and magnetostriction measurements were performed in temperatures down to 2 K and fields up to 15 T. For CoTiO₃ a strong magnetoelastic coupling is found and its phase diagram is constructed [1]. A phenomenological domain model is applied to explain its magnetostriction and magnetization data. Furthermore, a hydrostatic pressure dependence of the Néel temperature (T_N = 37 K) of dT_N/dp = 0.8 K/GPa is derived by a Grüneisen analysis. This analysis also shows a single dominant energy scale in CoTiO₃ below 50 K. For the R₄Ni₃O₁₀ compounds, on the other hand, Grüneisen analyses indicate competing interactions just below the metal-to-metal transition temperatures T_M and pressure dependencies of dT_M/dp = −8 K/GPa, −4 K/GPa and −3 K/GPa for R = La, Pr, Nd, respectively [2]. Clear anomalies in the thermal expansion at T_M for all three compounds show strong coupling between the electronic and lattice degrees of freedom. [1] M. Hoffmann, K. Dey, J. Werner, R. Bag, J. Kaiser, H. Wadepohl, Y. Skourski, M. Abdel-Hafiez, S. Singh, and R. Klingeler, Phys. Rev. B (accepted 2021) [2] D. Rout, S. R. Mudi, M. Hoffmann, S. Spachmann, R. Klingeler, and S. Singh, Phys. Rev. B 102, 195144 (2020).