SKM 2023 – scientific programme
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MA: Fachverband Magnetismus
MA 40: Poster Magnetism II
MA 40.56: Poster
Thursday, March 30, 2023, 14:00–16:00, P2/EG
Magnetoelastic coupling and magnetic anisotropy in LiMnPO4 — •Timo Kleinbek1, Sven Spachmann1, Martin Jonak1, Mahmoud Abdel-Hafiez2, and Rüdiger Klingeler1 — 1Kirchhoff Institute for Physics, Heidelberg University, Germany — 2Department of Physics and Astronomy, Uppsala University, Sweden
We report high-resolution capacitance dilatometry, magnetisation, and high-frequency electron-spin-resonance studies on LiMnPO4 single crystals. Our findings imply sizeable magnetoelastic coupling as demonstrated by large anomalies in the thermal expansion coefficients associated with the evolution of long-range magnetic order at TN = 33 K. We extract the uniaxial pressure dependencies. Existence of short-range magnetic order above TN is indicated by magnetic entropy changes up to around 70 K. A spin flip for B||b-axis is indicative of a Dzyaloshinskii-Moriya-interaction-caused spin-canting in the ground state. The magnetic phase diagrams are constructed for the three crystallographic directions. The field dependence of the magnon branches implies a two-sublattice model of antiferromagnetic resonance with orthorhombic anisotropy. An anomalous magnon branch detected above the spin-flop field is shown to be accountable-for by a rotation of the easy anisotropy axis at the spin-flop field by 6.5∘ away from the a-axis towards the hard b-axis. With increasing temperature, the two zero-field excitation gaps remain distinct, implying the preservation of the orthorhombic anisotropy.