Structural transition and orbital glass physics in near itinerant CoV2O4

Abstract

The ferrimagnetic spinel $\mathrm{Co}{\mathrm{V}}_2{\mathrm{O}}_4$ has been a topic of intense recent interest, both as a frustrated insulator with unquenched orbital degeneracy and as a near-itinerant magnet which can be driven metallic with moderate applied pressure. Here, we report on our recent neutron diffraction and inelastic scattering measurements on powders with minimal cation site disorder. Our main new result is the identification of a weak ($\frac{\Delta a}{a}\sim 10^{-4}$), first order structural phase transition at $T^{\ast }$ = 90 K, the same temperature where spin canting was seen in recent single crystal measurements. This transition is characterized by a short-range distortion of oxygen octahedral positions, and inelastic data further establish a weak $\Delta \sim 1.25meV$ spin gap at low temperature. Together, these findings provide strong support for the local orbital picture and the existence of an orbital glass state at temperatures below $T^{\ast }$.

8 pages, 5 figures, To be published in Physical Review B

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Cited by in corpus (8)

• Unusual UUDD magnetic chain structure of the spin-1/2 tetragonally distorted spinel GeCu2O4
• Electronic States and Possible Origin of the Orbital-Glass State in a Nearly Metallic Spinel Cobalt Vanadate: An X-ray Magnetic Circular Dichroism Study
• A variety of elastic anomalies in orbital-active nearly-itinerant cobalt vanadate spinel
• Spin Canting and Orbital Order in Spinel Vanadate Thin Films
• Large Magnetic Anisotropy and Magnetostriction in Thin Films of CoV${}_2$O${}_4$
• Domain wall patterning and giant response functions in ferrimagnetic spinels
• Orbital order and electron itinerancy in CoV${}_2$O${}_4$ and Mn${}_{0.5}$Co${}_{0.5}$V${}_2$O${}_4$ from first principles
• Localized-delocalized crossover of spin-carriers and magnetization reversal in Co${}_2$VO${}_4$