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
BaCo0​.62Zn1​.38Fe1​6O2​7, 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 K1​ = 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