Field-Induced Structural Transition in the Bond Frustrated Spinel ZnCr2Se4.

The effect of an external magnetic field on the structural and magnetic properties of bond frustrated ZnCr2Se4 at low temperatures is investigated using magnetization, dielectric constants and thermal conductivity experiments. With an increase in the magnetic field H, the antiferromagnetic transition temperature TN is observed to shift progressively toward lower temperatures. The corresponding high temperature cubic (Fd3̄m) to low temperature tetragonal (I41amd) structural transition is tuned simultaneously due to the inherent strong spin-lattice coupling. In the antiferromagnetic phase, an anomaly at HC2 defined as a steep downward peak in the derivative of the M–H curve is clearly drawn. It is found that TN versus H and HC2 versus T exhibit a consistent tendency, indicative of a field-induced tetragonal (I41amd) to cubic (Fd3̄m) structural transition. The transition is further substantiated by the field-dependent dielectric constant and thermal conductivity measurements. We modify the T–H phase diagram, highlighting the coexistence of the paramagnetic state and ferromagnetic clusters between 100 K and TN. [ABSTRACT FROM AUTHOR]