Strain-induced magnetic planar Hall effect in antiferromagnetic Nd₂Ir₂O₇ thin film

In topological magnetic materials, external magnetic field, H_ext, couples with intrinsic magnetic structures, leading to complex topological magnetic behavior such as anomlaous and quantized hall effect. While most of studies have been focuesed on ferromagnetic materials, the progress on antiferromagnetic (AFM) materials is just at the beginning. due to their robustness of external perturbation and vanishingly small magnetization. Recently, the torque-magnetometry study on AFM Eu₂Ir₂O₇ suggests that applying H_ext in-plane direction on Eu₂Ir₂O₇ can produce nonlinear magnetization M_Ʇ, which is orthogonal to the H_ext [1]. Theoretically, such M_Ʇ   could originated from higher magnetic ordering, octuople [1]. However, the  further epxereimental study of octupolar orthongonal magnetization, M_Ʇ^o, remains elusive. Here, we present the study of M_Ʇ^o in  AFM fully-strained Nd_­2Ir₂O₇ thin film using various magneto-transport technique. Nd_­2Ir₂O₇ belongs to one of All-in-All-out (AIAO) antiferromagnetic pyrochlore irdate family. With the epitaxial strain, Nd_­2Ir₂O₇ becomes metallic and the AIAO ordering expereience spin canting. Such canted AIAO are knwon as the addition of three spin clusters (Dipole, A₂-octupole and T₁-octupole) [2]. The generation of two octuopolar ordering creates non-vanishing Berry curvature and induces anomalous Hall effect. Moreover, using in-plane rotational transport measurement, we found that the two octupoles can induce M_Ʇ^o  and affect in-plane anomalous and planar Hall effect in Nd_­2Ir₂O₇ thin film. Our work highlights on the interplay of strain, topology, and magnetism in antiferromagnetic materials.

References

[1] T. Liang et al., Nat. Phys. 13 (2017) 599-603.