Low-temperature orthorhombic phase stabilization and magneto-dielectric coupling in Mn2.7Cr0.3O4

Gopeshwar Dhar Dwivedi^1*, S. M. Kumawat^1,2, C. W. Wang³, D. Chandrasekhar Kakarla¹, H. D. Yang¹, S. J. Sun⁴, H. Chou^1,4

¹Department of Physics and Center of Crystal Research, National Sun Yat-sen University, Kaohsiung, Taiwan
²International Ph.D. program for Science (IPPS), National Sun Yat-sen University, Kaohsiung, Taiwan
³National Synchrotron Radiation Research Center, Hsinchu, Taiwan
⁴Department of Applied Physics, National University of Kaohsiung, Kaohsiung, Taiwan

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

Spinel Mn2.7Cr0.3O4 exhibits ferrimagnetic transition and dielectric anomaly simultaneously around 45K. This suggests a correlation between magnetic and dielectric behaviors. A temperature-dependent neutron powder diffraction study revealed a simultaneous structural (tetragonal to orthorhombic phase) and magnetic transition in Mn2.7Cr0.3O4, i.e., the magnetic and structural transitions are linked. These results suggests the spin-lattice coupling controls magneto-dielectric behaviour of Mn2.7Cr0.3O4. The magnetic structure obtained from neutron diffraction study suggests that intrachain octahedral-octahedral exchange interaction is the most prominent interaction which provides canted antiferromagnetic (AFM) spin arrangement to the system. This results is contrary to the general belief that interaction between tetrahedral-octahedral cations are most prominent in the spinel systems.

Keywords: Structural transition, Spin-lattice coupling, Magneto-dielectric coupling, Neutron powder diffraction