Magnetostriction and piezomagnetism of noncollinear antiferromagnet Mn₃NiN

Abstract

Magnetoelastic effects in the three-sublattice noncollinear antiferromagnet Mn₃NiN are studied theoretically. Shear deformations are shown to give rise in the crystal to a piezomagnetic moment of an exchange nature. The magnitude of the piezomagnetic moment is comparable with the weak ferromagnet moment detected experimentally in Mn₃NiN. The absence of critical softening of sound waves near spinorientational phase transitions is demonstrated. It is proved that the experimentally observed temperature hysteresis at a first-order phase transition from the para- to antiferromagnet state is due to exchange magnetostriction.

Key Words:

• Magnetoelastic effect
• piezomagnetism
• noncollinear antiferromagnet
• Mn₃NiN
• first-order phase transition