Piezomagnetism

piezomagnetism [pē¦ā·zō′mag·nə‚tiz·əm]

(solid-state physics)

Stress dependence of magnetic properties.

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Piezomagnetism 

the appearance of magnetization in a substance that is subjected to external pressure. Piezomagnetism can exist only in substances whose magnetic structure is antiferromagnetic; as a rule, therefore, piezomagnetism is not possible in paramagnetic and diamagnetic substances. Piezomagnetism is produced when the applied pressure changes the magnetic symmetry of an antiferromagnetic crystal in such a way that a weak ferromagnetism arises. Magnetization of the sample occurs as a result of the tilting of the antiferromagnetic sublattices or a change in their relative magnitudes of magnetization.

So far, piezomagnetism has been detected experimentally in only three antiferromagnetic crystals: MnF₂, CoF₂, and α-Fe₂O₃. In these crystals, the extent of magnetization J_i is proportional to the applied compressive stress σ_kl’ that is, J_i = ∧_iklσ_kl. Piezomagnetism is not strong; the maximum value of the coefficient ∧_ikl (in CoF₂) is 2 × 10^-3 gauss = cm²/kilogram force (~2 × 10^-12 tesla = m²/newton). There is also a thermodynamically converse effect, the linear magnetostriction of antiferromagnets. Here, the linear dimensions of crystals change in proportion to the intensity of the applied magnetic field.

REFERENCE

Vonsovskii, S. V. Magnetizm. Moscow, 1971. Page 758.

A. S. BOROVIK-ROMANOV