Giant Piezomagnetism and Piezoimpedance Effects in MnZn Ferrite Device under Hydrostatic Pressure

The effects of hydrostatic pressure on the magnetism and impedance of a manganese zinc ferrite device were investigated.Both giant piezopermeability and piezoimpedance which were independent of skin effect were observed simultaneously under pressure of a few million-pascals(MPa).With increasing frequency of the current applied across the search coil of the ferrite device,these pressure effects are found to undergo a maximum at frequency of about 1kHz.Under pressure of 6MPa,piezoimpedance over 60% is observed for the ferrite devices with the permeabilities ranging from 5000 to 15000.Analysis shows that these pressure effects result from the variation of the interior stress and the magnetization of the ferrite induced by the applied pressure.