Antiferromagnetic Mn3NiN thin films supporting giant piezomagnetism*

Controlling magnetism with electric field directly or through strain-driven piezoelectric coupling remains a key goal of spintronics. Here we demonstrate that giant piezomagnetism, a linear magneto-mechanic coupling effect, is manifest in antiperovskite Mn₃NiN, facilitated by its geometrically frustrated antiferromagnetism opening the possibility of new memory device concepts. Films of Mn₃NiN with intrinsic biaxial strains of 0.25% result in Néel transition shifts up to 60K and magnetisation changes consistent with theory [1]. Films grown on BaTiO₃ display a striking magnetisation jump in response to uniaxial strain from the intrinsic BaTiO₃ structural transition, with an inferred 44% strain coupling efficiency and a magnetoelectric coefficient approximately a 1000-fold increase over Cr₂O₃ as predicted previously by theory. Overall our observations pave the way for further research into the broader family of Mn-based antiperovskites where yet larger piezomagnetic effects are predicted to occur at room temperature [2]. In this talk we will review progress towards application of thin film piezomagnetism in Mn3NiN.
[1] J. Zemen et al., Phys Rev B 96, 024451 (2017) [2] D. Boldrin et al., ASC Appl. Mater. Interfaces 10 18863 (2018)