Berry curvature induced spontaneous and topological-like Hall effect in magnetic Weyl semimetallic Nd2Ir2O7 (111) thin films

Abstract

We report a study of longitudinal resistivity, anisotropic magnetoresistance (MR), and Hall effect on epitaxial Nd2Ir2O7 (111) thin films grown by the solid phase epitaxy technique, in which spin–orbit coupling, electronic correlation, magnetic frustration, and f-d exchange interaction are present. Temperature-dependent longitudinal resistivity (ρxx) data indicate semimetallic charge transport in the low-temperature region. Field-cooled longitudinal resistivity measurements detect negligible domain-wall conductance compared to the polycrystal or single-crystal samples. Angle-dependent MR measurement shows that the magnetic structure of Ir4+ 5d moments can be finely tuned by applying a magnetic field along different crystallographic directions. MR measurements show a field-induced modification of the Nd3+ 4f spin structure from all-in-all-out/all-out-all-in (AIAO/AOAI) (4-in-0-out) to 1-in-3-out for the applied field (H) along the [111] direction, resulting in field-induced plastic deformation of the Ir4+ domain distribution. In contrast, the application of field (H) along the [001] and [011] directions could not modify any domain distribution. A large spontaneous Hall effect (SHE) signal has been observed on Nd2Ir2O7 (111) thin film with AIAO/AOAI antiferromagnetic ordering for the application of field (H) along [001], [1̄1̄0], and [111] directions. The appearance of a large spontaneous Hall signal for the applied field along [001] and [1̄1̄0] directions rules out domain switching as the origin of the Hall effect and confirms the presence of the Weyl semimetallic phase in Nd2Ir2O7 (111) thin films. In addition to SHE, a large topological-like Hall signal is also observed, possibly due to the presence of multiple Weyl nodes in the electronic band structure.