Spin Fluctuations and Frustrated Magnetism in the Multiferroic FeVO${}_4$

Abstract

We report ${}^{51}$V nuclear magnetic resonance (NMR) studies on single crystals of the multiferroic material FeVO${}_4$. The high-temperature Knight shift shows Curie-Weiss behavior, ${}^{51}K=a/(T+\theta )$, with a large Weiss constant $\theta \approx$ 116 K. However, the ${}^{51}$V spectrum shows no ordering near these temperatures, splitting instead into two peaks below 65 K, which suggests only short-ranged magnetic order on the NMR time scale. Two magnetic transitions are identified from peaks in the spin-lattice relaxation rate, $1{/}^{51}{T}_1$, at temperatures $T_{N1}\approx$ 19 K and $T_{N2}\approx$ 13 K, which are lower than the estimates obtained from polycrystalline samples. In the low-temperature incommensurate spiral state, the maximum ordered moment is estimated as 1.95${\mu }_B$/Fe, or 1/3 of the local moment. Strong low-energy spin fluctuations are also indicated by the unconventional power-law temperature dependence $1{/}^{51}{T}_1\propto T^2$. The large Weiss constant, short-range magnetic correlations far above $T_{N1}$, small ordered moment, significant low-energy spin fluctuations, and incommensurate ordered phases all provide explicit evidence for strong magnetic frustration in FeVO${}_4$.

7 pages, 4 figures, published in Phys. Rev. B

References in corpus (3)

• Magnetically driven ferroelectric order in Ni${}_3$V${}_2$O${}_8$
• Ferroelectric polarization flop in a frustrated magnet MnWO${}_4$ induced by magnetic fields
• Multiferroicity in the geometrically frustrated FeTe2O5Cl

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