1210.0997 (Martino Lobue et al.)

Direct calorimetric measurements of isothermal entropy change on single
crystal W-type hexaferrites at the spin reorientation transition    [PDF]

Martino Lobue, Vincent Loyau, Frédéric Mazaleyrat, Alexander Pasko, Vittorio Basso, Michaela Küpferling, Carlo Paolo Sasso

We report on the magnetic field induced isothermal entropy change, \Delta s(Ha, T), of W-type ferrite with CoZn substitution. Entropy measurements are performed by direct calorimetry. Single crystals of the composition BaCo$_0.62$Zn$_1.38$Fe$_16$O$_27$, prepared by the flux method, are measured at different fixed temperatures under an applied field perpendicular and parallel to the c axis. At 296 K one deduces a value of K$_1$ = 8.7 \times 10^{4} J m$^-3$ for the first anisotropy constant, which is in good agreement with the literature. The spin reorientation transition temperature is estimated to take place between 200 and 220 K.

View original: http://arxiv.org/abs/1210.0997