Giant Piezomagnetism in Mn₃NiN

Abstract

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 MnNiN, facilitated by its geometrically frustrated antiferromagnetism opening the possibility of new memory device concepts. Films of MnNiN 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 BaTiO display a striking magnetization jump in response to uniaxial strain from the intrinsic BaTiO structural transition, with an inferred 44% strain coupling efficiency and a magnetoelectric coefficient α (where α = d B/d E) of 0.018 G cm/V. The latter agrees with the 1000-fold increase over CrO 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.

Electric‐Field‐Controlled Antiferromagnetic Spintronic Devices

“…Meanwhile, Boldrin et al systematically researched the interface-induced strain effects on antiferromagnetic Mn 3 NiN thin films by growing it on different substrates. [78,79] It was found that under biaxial or uniaxial strain, the symmetry of the antiperovskite structure (Figure 7a) could be destroyed, which leads to changes in the Néel temperature ( Figure 7b) and magnetization ( Figure 7c). For biaxial strain, the Néel temperature has an almost linear dependence on strain, and modulation of ≈60 K by ± 0.25% strain (Figure 7b).…”

“…d) Temperature‐dependent magnetization of Mn 3 NiN films grown on BaTiO 3 . Reproduced with permission 78. Copyright 2018, American Chemical Society.…”

Antiperovskites with Exceptional Functionalities

“…Typically, Mn 3 Ga 0.95 N 0.94 was reported to exhibit a remarkable so‐called “baromagnetic effect,” i.e., a magnetic phase transition caused by external hydrostatic pressure. Piezomagnetism was studied theoretically in a series of magnetically frustrated Mn‐based antiperovskite nitrides and experimentally in Mn 3 NiN . Boldrin et al studied the multisite exchange‐enhanced barocaloric response in Mn 3 NiN across the Néel transition temperature .…”

“…Piezomagnetism was studied theoretically in a series of magnetically frustrated Mn-based antiperovskite nitrides and experimentally in Mn 3 NiN. [176,177] Boldrin et al studied the multisite exchangeenhanced barocaloric response in Mn 3 NiN across the Néel transition temperature. [178] All these findings highlight the potential of discovering novel materials with enhanced multifunctionalities in the broad and chemically flexible antiperovskite family.…”

Metal‐Rich Ternary Perovskite Nitrides

“…[135] A large negative thermal expansion below the Néel temperature of 264 K results from magnetostriction during a continuous spin rearrangement, which might be controlled by the degree of substitution in Mn 4-x Ni x N. [136] Additionally, a magneto-mechanical coupling results in an abnormal large piezomagnetic effect. [137] Mn 3 RhN and Mn 3 PdN also realize antiferromagnetic order below about 226 K and 316 K. [134,138] While Mn 3 PtN, like the two aforementioned noble metal compounds, remains cubic, with reduced nitrogen content Mn 3 PtN 0.25 and Mn 3 RhN 0.2 crystallize in a hexagonal 2H-perovskite structure (BaNiO 3 -type structure, see Figure 3). [139] Upon cooling, cubic Mn 3 ZnN changes from a Curie paramagnet to an antiferromagnet below about 180 K, with a magnetic rearrangement at 127.5 K. [134,140] Interestingly, in a temperature interval of 140 K -177 K two different magnetic structures were observed to coexist.…”