Regensburg 2022 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 12: Correlated Electrons: Materials
TT 12.5: Vortrag
Dienstag, 6. September 2022, 10:30–10:45, H22
Magnetic anisotropy, magnetoelastic coupling and the phase diagram of Ni0.25Mn0.75TiO3 — •Ahmed Elghandour, Lukas Gries, Lennart Singer, Kaustav Dey, and Rüdiger Klingeler — Kirchhoff Institute for Physics, Heidelberg University, Heidelberg, Germany
Thermodynamic studies on high-quality single crystals of Ni0.25Mn0.75TiO3 have been used to investigate magneto-structural coupling and to construct the magnetic phase diagram. Clear anomalies in the thermal expansion at the spin ordering and spin reorientation temperatures, TN and TR, evidence pronounced magneto-elastic effects. Notably, magnetic entropy is released mainly above TN implying considerable short range magnetic order up to about 4TN. This is associated with a large regime of negative thermal expansion of the c axis. Both TN and TR exhibit the same sign of uniaxial pressure dependence which is positive (negative) for pressure applied along the b (c) axis. In addition, while our data indicate a glassy behaviour below T*≈ 3.7 K, a significant amount of Ni2+ moments seems neither involved in long-range order not in the glassy state.