Effect of hydrostatic pressure on the magnetization mechanisms in Ni-Zn ferrite

In this paper we investigate the influence of hydrostatic pressure (up to 1000 bar) on the magnetization mechanisms of spinel polycrystalline ferrites. The results presented here have been obtained on the composition Ni
.36
Zn
.64
Fe
2
O
4
. We show that : - the inverse of the initial susceptibility increases linearly with the pressure, - both the critical field H
cr
, where the susceptibility begins to increase sharply, and the field H
m
corresponding to the maximum of susceptibility, increase also linearly with the pressure. Similar laws have been found for the same composition at other temperatures, as well as for different compositions, - a new phenomenon has to be noted : a "pressure induced hysteresis" of the initial susceptibility, - the initial magnetization curves for different pressures can be reduced to a single curve by taking into account the ratio H/H
cr
(where H
cr
is the critical unpinning field for the domain walls). The interpretation is based on a model previously proposed by Globus.