Giant Piezomagnetism in Mn₃NiN

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 60 K and magnetization changes consistent with theory. Films grown on BaTiO₃ display a striking magnetization jump in response to uniaxial strain from the intrinsic BaTiO₃ structural transition, with an inferred 44% strain coupling efficiency and a magnetoelectric coefficient α (where α = dB/dE) of 0.018 G cm/V. The latter agrees with the 1000-fold increase over Cr₂O₃ predicted 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.