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Magnetocaloric effect in pyrochlore antiferromagnet Gd2Ti2O7

S. S. Sosin·L. A. Prozorova·A. I. Smirnov·A. I. Golov·I. B. Berkutov·O. A. Petrenko·G. Balakrishnan·M. E. Zhitomirsky
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Abstract

An adiabatic demagnetization process is studied in Gd2Ti2O7, a geometrically frustrated antiferromagnet on a pyrochlore lattice. In contrast to conventional paramagnetic salts, this compound can exhibit a temperature decrease by a factor of ten in the temperature range below the Curie-Weiss constant. The most efficient cooling is observed in the field interval between 120 and 60 kOe corresponding to a crossover between saturated and spin-liquid phases. This phenomenon indicates that a considerable part of the magnetic entropy survives in the strongly correlated state. According to the theoretical model, this entropy is associated with a macroscopic number of local modes remaining gapless till the saturation field. Monte Carlo simulations on a classical spin model demonstrate good agreement with the experiment. The cooling power of the process is experimentally estimated with a view to possible technical applications. The results for Gd2Ti2O7 are compared to those for Gd3Ga5O12, a well-known material for low temperature magnetic refrigeration.

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S. S. Sosin, L. A. Prozorova, A. I. Smirnov, A. I. Golov, I. B. Berkutov, O. A. Petrenko, G. Balakrishnan, M. E. Zhitomirsky. 2004-12-17. Magnetocaloric effect in pyrochlore antiferromagnet Gd2Ti2O7. https://doi.org/10.1103/physrevb.71.094413

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