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mardi 9 mars — 14:00

Magnetocaloric Properties of Quantum Antiferromagnets

Andreas Honecker (Université de Göttingen)

par Pierre Pujol - 9 mars 2010

The antiferromagnetic spin-1/2 Heisenberg chain is one of the best studied model systems in quantum magnetism. Nevertheless, the magnetocaloric effect, i.e., the temperature change under adiabatic changes of an applied magnetic field, has attracted surprisingly little attention. We start by reviewing certain historical aspects. Then we present new numerical and exact results for the cooling rate in the spin-1/2 Heisenberg chain and perform a comparison with recent experiments on the copper coordination polymer [Cu($\mu$-C$_2$O$_4$)(4-aminopyridine)$_2$(H$_2$O)]$_n$. Finally, we point out that competing interactions enhance the magnetocaloric effect which occurs in the vicinity of a field-induced quantum phase transition such that related materials are promising candidates for efficient low-temperature magnetic refrigeration.