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MA: Fachverband Magnetismus

MA 3: Complex Oxides: Bulk Properties (jointly with DS, HL, KFM, MA, O) (joint session TT/HL/MA)

MA 3.10: Vortrag

Montag, 16. März 2020, 12:00–12:15, HSZ 201

Magnetic Phase diagram and thermal expansion studies of NiTiO₃ — •Kaustav Dey¹, Sven Sauerland¹, Johannes Werner¹, Rabindranath Bag², Surjeet Singh², and Rüdiger Klingeler¹ — ¹Kirchhoff Institute of Physics , Heidelberg University, Germany — ²IISER Pune, Maharashtra, India

We report the magnetic phase diagram of S=1 magnetodielectric NiTiO₃ single crystals grown by the optical floating zone technique. The high-quality single crystals have been studied by specific heat, by magnetometry up to 60 T, and by thermal expansion and magnetostriction measurements up to 15 T, respectively. The compound evolves long-range antiferromagnetic order at T_N = 22.5 K with spins lying in the ab−plane. Pronounced anomalies in the thermal expansion coefficients (α_i, (i=a,b)) at T_N indicate strong magnetoelastic coupling in NiTiO₃. Magnetic length and entropy changes as detected by α and c_p obey Grüneisen scaling which evidences one dominant (spin) degree of freedom driving the transitions. In addition, the magnetic phase diagram features a spin-reoriented phase below B_c=1.2 T which suggests the presence of a small in-plane anisotropy. Notably, spin-reorientation is associated with a first-order-like anomaly in the magnetostriction. The high-field behavior of magnetization is linear and isotropic with saturation at 36 T thereby facilitating constructing the entire magnetic phase diagram.