Electrical current switching of the noncollinear antiferromagnet Mn3GaN

Abstract

We report electrical current switching of noncollinear antiferromagnetic (AFM) Mn 3 GaN/Pt bilayers at room temperature. The Hall resistance of these bilayers can be manipulated by applying a pulse current of 1.5 × 10 6 A/cm 2 , whereas no significant change is observed up to ∼ 10 8 A/cm 2 in Mn 3 GaN single films, indicating that the Pt layer plays an important role. In comparison with ferrimagnetic Mn 3 GaN/Pt bilayers, a lower electrical current switching of noncollinear AFM Mn 3 GaN is demonstrated, with a critical current density two orders of magnitude smaller. Our results highlight that a combination of a noncollinear AFM antiperovskite nitride and a spin-torque technique is a good platform of AFM spintronics.Antiferromagnets (AFMs) are promising materials for spintronics application owing to a number of properties, such as the absence of stray magnetic fields, terahertz spin dynamics, and stability against external perturbations, and, in this context, electrical manipulation of the Néel vector is an important emerging technique. [1][2][3][4] Recent experiments have demonstrated electrical current switching of the AFM Néel vector by Néel spinorbit torque (SOT) in CuMnAs 5,6 and Mn 2 As, 7,8 and by spin torque in NiO/Pt bilayers 9,10 and Pt/NiO/Pt trilayers. 11 These experiments show that the AFM Néel vector can be manipulated by electrical current densities of the order of 10 7 -10 8 A/cm 2 , which are similar to the current densities required with SOT in typical ferromagnet (FM)/heavy metal (HM) bilayers. On the other hand, according to an early study of AFM spintronics, 12 a current density two orders of magnitude smaller may theoretically be capable of manipulating the AFM Néel vector. Indeed, current-induced switching of exchange bias at such lower current densities has been realized in AFM/FM bilayers. [13][14][15] These results suggest the possibility of switching of the AFM Néel vector using lower electrical currents.Recently, noncollinear AFMs become one of the most fascinating classes among AFMs, because they exhibit a large magneto-transport and a novel spin transport phenomena. [16][17][18][19] However, the spin-torque switching of the AFM Néel vector is demonstrated in only collinear AFM, while the theoretical study shows that the domain of noncollinear AFM can be manipulated by spin current with realistic current density of ∼ 10 7 A/cm 2 . 20 Thus, noncollinear AFMs call for the spin current injection thorough spin-Hall effect. The antiperovskite manganese nitrides Mn 3 GaN (MGN) is a good platform to investigate the electrical current manipulation of noncollinear AFMs, as well as for comparisons of the critical current density between FM and AFM materials, because MGN is a noncollinear AFM while a perpendicularly magnetized ferrimagnet can be obtained by applying tetragonal distortion. [21][22][23] Both the Néel and Curie temperatures are reported to be above 380 K 24 and 660-740 K, 21,22 a) Electronic mail: t.hajiri@nagoya-u.jp respectively, which are relatively high for this class of materi...

Scaling the electrical current switching of exchange bias in fully epitaxial antiferromagnet/ferromagnet bilayers

“…Another possibility would be a double helical AFM MnP 59 and CrAs 60 , which have 1.3µ B /Mn and 1.7µ B /Cr, respectively, and it is worthy of future research on those AFM switching. We note that the similar order of switching current density has been recently realized in the SOT of noncollinear AFM of MGN(2.43 µ B /Mn) and Mn 3 Sn(3.2 µ B /Mn 61 ) with 1.5 and 5 × 10 6 A/cm 2 , respectively 16,17 . Since STT consumes more energy than SOT in traditional STT and SOT of FM 62 , our results may imply that SOT in such AFMs has a great potential to realize even lower current density switching.…”

Electric‐Field‐Controlled Antiferromagnetic Spintronic Devices

“…In addition to the resistance modulation of collinear antiferromagnets, the electrical switching of noncollinear antiferromagnetic memory devices was achieved as well. Hajiri et al reported the switching of the magnetic order parameter of the noncollinear antiferromagnet Mn 3 GaN through an electric current in an experiment in 2019 ( Figure ) 46. They found that the manipulation of the Hall resistance in the Mn 3 GaN/Pt bilayer can be induced by a pulse current, which disappeared in the single Mn 3 GaN layer, and thus inferred the switching of noncollinear Mn 3 GaN antiferromagnet is caused by the spin–orbit torque.…”

“…Hajiri et al reported the switching of the magnetic order parameter of the noncollinear antiferromagnet Mn 3 GaN through an electric current in an experiment in 2019 (Figure 3). [46] They found that the manipulation of the Hall resistance in the Mn 3 GaN/Pt bilayer can be induced by a pulse current, which disappeared in the single Mn 3 GaN layer, and thus inferred the switching of noncollinear Mn 3 GaN antiferromagnet is caused by the spin-orbit torque. This work demonstrates the possibility of electrical switching of a noncollinear antiferromagnet using the spin-orbit torque.…”

“…b) Dependence of the Hall resistance to the current density. Reproduced with permission [46]. Copyright 2019, American Institute of Physics.…”

Spin-torque switching of noncollinear antiferromagnetic antiperovskites

“…The spin current can be generated from a non-metal bottom layer through the spin Hall effect. Recently, such a spin-Hall torque switching has been reported in the GaNMn 3 (001)/Pt bilayer structure [75]. In this experiment that AFM switching was detected using a conventional AMR effect, since the noncollinear AFM Γ 5g phase in Mn 3 GaN does not support the AHE [29].…”