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arXiv · 1405.2272

Magnetic excitations and anomalous spin wave broadening in multiferroic FeV2O4

Qiang Zhang·Mehmet Ramazanoglu·Songxue Chi·Yong Liu·Thomas. A. Lograsso·David Vaknin
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Abstract

We report on the different roles of two orbital-active Fe$^{2+}$ at the A site and V$^{3+}$ at the B site in the magnetic excitations and on the anomalous spin wave broadening in FeV$_{2}$O$_{4}$. FeV$_{2}$O$_{4}$ exhibits three structural transitions and successive paramagnetic (PM)-collinear ferrimagnetic (CFI)-noncollinear ferrimagnetic (NCFI) transitions. The high-temperature tetragonal/PM -orthorhombic/CFI transition is accompanied by the appearance of an energy gap with a high magnitude in the magnetic excitations due to strong spin-orbit coupling induced anisotropy at the Fe$^{2+}$ site. While there is no measurable increase in the energy gap from the orbital ordering of V$^{3+}$ at the orthorhombic/CFI-tetragonal/NCFI transition, anomalous spin wave broadening is observed in the orthorhombic/CFI state due to V$^{3+}$ spin fluctuations at the B site. The spin wave broadening is also observed at the zone boundary without softening, which is discussed in terms of magnon-phonon coupling.

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Qiang Zhang, Mehmet Ramazanoglu, Songxue Chi, Yong Liu, Thomas. A. Lograsso, David Vaknin. 2014-05-09. Magnetic excitations and anomalous spin wave broadening in multiferroic FeV2O4. https://doi.org/10.1103/physrevb.89.224416

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