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arXiv · 0808.3789

Magnetic phase evolution in the spinel compounds Zn$_{1-x}$Co$_x$Cr$_2$O$_4$

Brent C. Melot·Jennifer E. Drewes·Ram Seshadri·Arthur P. Ramirez
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Abstract

We present the magnetic properties of complete solid solutions of ZnCr$_2$O$_4$ and CoCr$_2$O$_4$: two well-studied oxide spinels with very different magnetic ground states. ZnCr$_2$O$_4$, with non-magnetic $d^{10}$ cations occupying the A site and magnetic $d^3$ cations on the B site, is a highly frustrated antiferromagnet. CoCr$_2$O$_4$, with magnetic $d^7$ cations (three unpaired electrons) on the A site as well, exhibits both Néel ferrimagnetism as well as commensurate and incommensurate non-collinear magnetic order. More recently, CoCr$_2$O$_4$ has been studied extensively for its polar behavior which arises from conical magnetic ordering. Gradually introducing magnetism on the A site of ZnCr$_2$O$_4$ results in a transition from frustrated antiferromagnetism to glassy magnetism at low concentrations of Co, and eventually to ferrimagnetic and conical ground states at higher concentrations. Real-space Monte-Carlo simulations of the magnetic susceptibility suggest that the first magnetic ordering transition and features of the susceptibility across $x$ are captured by near-neighbor self- and cross-couplings between the magnetic A and B atoms. We present as a part of this study, a method for displaying the temperature dependence of magnetic susceptibility in a manner which helps distinguish between compounds possessing purely antiferromagnetic interactions from compounds where other kinds of ordering are present.

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Brent C. Melot, Jennifer E. Drewes, Ram Seshadri, Arthur P. Ramirez. 2009-06-04. Magnetic phase evolution in the spinel compounds Zn$_{1-x}$Co$_x$Cr$_2$O$_4$. https://doi.org/10.1088/0953-8984%2F21%2F21%2F216007

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