Abstract:

The temperature dependence of the EPR spectrum for the α-phase of iron tungstate has been investigated in the temperature range of 40-260 K. At temperatures between T1 ≈ 250 K and T2 ≈ 205 K where the antiferromagnetic phase transition occurs, a relatively narrow EPR line arising from the dominant iron(III) species has emerged, gaining intensity with the temperature increase. Its linewidth temperature evolution could be described by Huber equation, with TN = 200 K, which is consistent with the peak seen in magnetic susceptibility measurements, while the corresponding g-factor shifts to higher fields reflecting the build-up of internal field emerging from increasing short-range order in the spin system. At temperatures lower than T2, a very broad and distorted EPR line with temperature dependent g-factor and linewidth has been observed reflecting the corresponding rise of the magnetic susceptibility below the antiferromagnetic phase transition, presumably arising from magnetic clusters embedded in the antiferromagnetic background. © Springer-Verlag 1998.

Notes:

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