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MA: Fachverband Magnetismus

MA 4: Magnetic Heusler Compounds and Complex Magnetic Oxides

MA 4.7: Talk

Monday, March 18, 2024, 11:15–11:30, EB 107

Large thermal Hall effect in the ordered phase of EuTiO₃ — •Rohit Sharma, Johannes Engelmayer, Lara Pätzold, and Thomas Lorenz — II. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, D-50937 Köln, Germany

We present the observation of a large thermal Hall effect in the quantum paraelectric compound EuTiO₃. Additionally, in EuTiO₃ the magnetic moments of Eu²⁺ order antiferromagnetically in a G-type configuration at T_N ≈ 5.5 K [1]. A magnetic field of ≈ 1.5T is already sufficient to change from antiferromagnetic to polarized ferromagnetic state. We have observed a glasslike longitudinal thermal conductivity (κ_xx) in this material, which can be attributed to spin lattice coupling [2]. Temperature dependence of transverse thermal Hall conductivity (κ_xy) looks similar to κ_xx in the paramagnetic regime. Field dependence of κ_xy shows linear behaviour with a positive sign in the paramagnetic regime, but becomes very large with a highly non-monotonic when measured in the ordered phase. It shows a large negative signal in the low field range which changes sign to a small positive signal for high field values. The positive signal at higher field values can be scaled well with the magnetization data measured at same temperature. The origin of the large negative signal is not clear and possible reasons for the its occurrence in EuTiO₃ will be discussed.
Funded by the DFG via Project No. LO 818/6-1.
[1] J. Engelmayer et al. Phys. Rev. Mater. 3, 051401(R) (2019)
[2] A. Jaoui et al. Phys. Rev. Mater. 7, 094604 (2023)

Keywords: Thermal Hall effect; Thermal conductivity; Antiferromagnetism; Glasslike; Quantum paraelectric