Signature of magnetostrictive coupling and liquid-like short-range ordering in cubic Mn1.5Cr1.5O4

Gopeshwar Dhar Dwivedi^1*, C. W. Wang², Sagar Mal Kumawat¹, H. Chou¹

¹Department of Physics, and Center of Crystal Research, National Sun Yat-sen University, Kaohsiung, Taiwan
²National Synchrotron Radiation Research Center, Hsinchu, Taiwan

* Presenter:Gopeshwar Dhar Dwivedi, email:gopeshwardwivedi@gmail.com

Cubic Mn1.5Cr1.5O4 exhibits dielectric anomaly around ferrimagnetic ordering temperature and it also shows small magneto-dielectric effect below TN. Temperature-dependent neutron diffraction patterns of cubic Mn1.5Cr1.5O4 show the evolution of (1 1 1) magnetic peak follows Ising model at the vicinity of TN, similar to the field cooled magnetization curve. Lattice constant saturates below TN which suggests the presence of magnetostrictive coupling in cubic system. It could be concluded that magnetization and dielectric constant are correlated via magnetostriction. The magnetic diffuse scattering around (1 1 1) peak shows that background starts to develop into a hump-like structure around q=1.4Å-1 below 170K. Inverse susceptibility curve also starts to deviate from the Curie-Weiss law below T’ (~170K). These results confirm the development of a short-range magnetic correlation below 170K. The diffuse scattering exhibits a maxima at TN (56K) and then starts to converse towards magnetic Bragg peaks below TN, but did not completely disappears. This liquid-like short-range ordering develops due to the magnetic frustration present in the cubic system.

Keywords: Neutron diffraction pattern, Short-range magnetic correlation, Magnetic frustration