An orbital glass state of a nearly metallic spinel, CoV$_2$O$_4$

TL;DR

This study reveals an orbital glass state in CoV₂O₄, a nearly metallic spinel, characterized by subtle structural distortions and a transition from collinear to noncollinear ferrimagnetic order around 90 K, highlighting complex magnetic and orbital interactions.

Contribution

The paper provides experimental evidence for an orbital glass state in CoV₂O₄, linking magnetic, structural, and orbital phenomena in a frustrated metallic spinel.

Findings

Subtle crystal distortion along magnetization direction detected.

Transition from collinear to noncollinear ferrimagnetic order at 90 K.

Maximal crystal elongation coincides with magnetic transition.

Abstract

Strain, magnetization, and unpolarized and polarized neutron diffraction measurements were performed to study the magnetic and structural properties of spinel CoV$_{2}$O$_{4}$. Magnetostriction measurements indicate that a subtle distortion of the crystal along the direction of magnetization, $\Delta L/L \sim 10^{-4}$, exists and varies from elongation to contraction in a second order fashion upon cooling. Unpolarized and polarized single-crystal neutron experiments indicate that upon cooling the ferrimagnetic structure changes from collinear to noncollinear at $T \sim 90$ K, where the elongation of the crystal is maximized. These results imply the existence of an orbital glassy state in the nearly metallic frustrated magnet CoV$_{2}$O$_{4}$.