1 5 A ug 1 99 8 High frequency dielectric and magnetic anomaly at the phase transition in NaV
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چکیده
We found anomalies in the temperature dependence of the dielectric and the magnetic susceptibility of NaV 2 O 5 in the microwave and far infrared frequency ranges. The anomalies occur at the phase transition temperature T c , at which the spin gap opens. The real parts of the dielectric constants ǫ a and ǫ c decrease below T c. The decrease of ǫ a (except for the narrow region close to T c) is proportional to the intensity of the x-ray reflection appearing at T c. The dielectric constant anomaly can be explained by the zigzag charge ordering in the ab-plane appearing below T c. The anomaly of the microwave magnetic losses is probably related to the coupling between the spin and charge degrees of freedom in vanadium ladders.
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تاریخ انتشار 1998