Piezomagnetism is a phenomenon observed in some antiferromagnetic crystals. It is characterised by a linear coupling between the system's magnetic polarisation and mechanical strain. In a piezomagnetic, one may induce a spontaneous magnetic moment by applying physical stress, or a physical deformation by applying a magnetic field.
Piezomagnetism differs from the related property of magnetostriction; if an applied magnetic field is reversed in direction, the strain produced changes sense. Additionally, a non-zero piezomagnetic moment can be produced by mechanical strain alone, at zero field - this is not true of magnetostriction. [1] According to IEEE: "Piezomagnetism is the linear magnetomechanical effect analogous to the linear electromechanical effect of piezoelectricity. Similarly, magnetostriction and electrostriction are analogous second-order effects. These higher-order effects can be represented as effectively first-order when variations in the system parameters are small compared with the initial values of the parameters". [2]
The piezomagnetic effect is made possible by an absence of certain symmetry elements in a crystal structure; specifically, symmetry under inversion of either space or time forbid the property. [3]
The first experimental observation of piezomagnetism was made in 1960, in the fluorides of cobalt and manganese. [4]