Magnetic Field Induced Phase Transition in Spinel GeNi2O4

TL;DR

This study reveals a magnetic field-induced phase transition in GeNi2O4, showing anisotropic magnetic behavior and a new magnetic phase under high magnetic fields along specific crystallographic directions.

Contribution

It uncovers a previously unobserved magnetic phase in GeNi2O4 induced by magnetic field and elucidates the role of magnetic anisotropy and interactions in this transition.

Findings

Discovery of a new magnetic phase at H > 4 T along [111]

Confirmation of spin reorientation via neutron diffraction

Identification of magnetic anisotropy effects

Abstract

Cubic spinel GeNi2O4 exhibits intriguing magnetic properties with two successive antiferromagnetic phase transitions (TN1 12.1 and TN2 11.4 K) with the absence of any structural transition. We have performed detailed heat capacity and magnetic measurements in different crystallographic orientations. A new magnetic phase in presence of magnetic field (H > 4 T) along the [111] direction is revealed, which is not observed when the magnetic field is applied along the [100] and [110] directions. High field neutron powder diffraction measurements confirm such a change in magnetic phase, which could be ascribed to a spin reorientation in the presence of magnetic field. A strong magnetic anisotropy and competing magnetic interactions play a crucial role on the complex magnetic behavior in this cubic system.