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Seminário de Mecânica Estatística

O seminário de Mecânica Estatística desta semana (6a feira, 21/06/2013)

será apresentado às 16:00h na sala A5-01 do Instituto de Física.

Título: De Haas-von Alphen effect on magnetocaloric potentials
Apresentador: Mario Reis (UFF).

Resumo: Magnetocaloric effect (MCE) is an interesting property of materials,
in which these are able to expel/absorb heat from a thermal reservoir under
a magnetic field change (considering an isothermal process); or even
increase/decrease its temperature (considering an adiabatic process). These
effects are maximum around the critical temperature of the material and
therefore ferromagnetic materials are, by far, the most and intensively
material studied by the scientific community[1]. For this reason, diamagnetic
materials have never been studied on this context, until the present effort;
and a plenty of interesting features, with quantum signatures, were
discovered[2-6].
        The fundamental model to describe a diamagnetic material is an
electrons gas; and a huge applied magnetic field promotes a degeneracy, named
Landau levels. Oscillations on the thermodynamic quantities are found when the
Landau levels cross the Fermi level of the non-perturbed gas at low
temperatures regime, analogously to the de Haas-von Alphen effect. This talk
presents therefore the oscillatory behavior found on the MCE of diamagnetic
materials, that can be tuned as either inverse or normal, depending on the
value of the magnetic field change. These results open doors for applications
at quite low temperatures. We also considered the oscillating MCE on graphenes.
[1] M.S. Reis, Foundations of Magnetism, Elsevier-New York (2013).
[2] M.S. Reis, Applied Physics Letters 99 (2011) 052511.
[3] M.S. Reis, Solid State Communications 152 (2012) 921.
[4] M.S. Reis, Applied Physics Letters 101 (2012) 222405.
[5] M.S. Reis, Solid State Communications 161 (2013) 19.
[6] M.S. Reis and S. Soriano, Applied Physics Letters 102 (2013) 112903.