Magnetic phase diagram, magnetoelastic coupling, and Gruneisen scaling in CoTiO3

High-quality single crystals of CoTiO3 are grown and used to elucidate in detail structural and magnetostructural effects by means of high-resolution capacitance dilatometry studies in fields up to 15 T which are complemented by specific heat and magnetization measurements. In addition, we refine the single-crystal structure of the ilmenite (R (3) over bar) phase. At the antiferromagnetic ordering temperature T-N pronounced lambda-shaped anomaly in the thermal expansion coefficients signals shrinking of both the c and b axes, indicating strong magnetoelastic coupling with uniaxial pressure along c yielding six times larger effect on T-N than pressure applied in-plane. The hydrostatic pressure dependency derived by means of Gruneisen analysis amounts to partial derivative T-N/partial derivative p approximate to 2.7(4) K/GPa. The high-field magnetization studies in static and pulsed magnetic fields up to 60 T along with high-field thermal expansion measurements facilitate in constructing the complete anisotropic magnetic phase diagram of CoTiO3. While the results confirm the presence of significant magnetodielectric coupling, our data show that magnetism drives the observed structural, dielectric, and magnetic changes both in the short-range ordered regime well above T-N as well as in the long-range magnetically ordered phase.

Automated summary

High-quality single crystals of CoTiO3 were used to study the structural and magnetostructural effects in detail, revealing strong magnetoelastic coupling in high magnetic fields. The hydrostatic pressure dependency on the antiferromagnetic ordering temperature was analyzed, and the complete anisotropic magnetic phase diagram of CoTiO3 was constructed using high-field magnetization studies. Results show significant magnetodielectric coupling and the influence of magnetism on structural, dielectric, and magnetic changes in both short-range and long-range ordered phases.