Spin structure and spin Hall magnetoresistance of epitaxial thin films of the insulating non-collinear antiferromagnet SmFeO₃

Abstract

We report a combined study of imaging the antiferromagnetic (AFM) spin structure and measuring the spin Hall magnetoresistance (SMR) in epitaxial thin films of the insulating non-collinear antiferromagnet SmFeO 3 . Xray magnetic linear dichroism photoemission electron microscopy measurements reveal that the AFM spins of the SmFeO 3 (110) align in the plane of the film. Angularly dependent magnetoresistance measurements show that SmFeO 3 /Ta bilayers exhibit a positive SMR, in contrast to the negative SMR expected in previously studied collinear AFMs. The SMR amplitude increases linearly with increasing external magnetic field at higher magnetic field, suggesting that fieldinduced canting of the AFM spins plays an important role. In contrast, around the coercive field, no detectable SMR signal is observed, indicating that SMR of AFM and canting magnetization components cancel out. Below 50 K, the SMR amplitude increases sizably by a factor of two as compared to room temperature, which likely correlates with the long-range ordering of the Sm ions. Our results show that the SMR is a sensitive technique for non-equilibrium spin system of non-collinear AFM systems.

Effective strain manipulation of the antiferromagnetic state of polycrystalline NiO

“…This sign of the signal is surprising for an antiferromagnet 3,4 as it is consistent with the presence of a ferromagnetic component. Positive SMR has been previously reported for antiferromagnets, and is attributable to the existence of some residual interfacial moments [38][39][40] . We used space-averaged dichroism measurements to exclude the presence of a ferromagnetic interface caused by either proximity-induced magnetism in the Pt layer or unintentional uncompensated Ni monolayer inclusions.…”

“…In general, the measured SMR response is sensitive to both a net magnetization m (with cos 2 α dependence) and the Néel order n (with sin 2 α dependence) [38][39][40] . The net response is the sum of both, meaning that one observes the angular dependence of the dominating mechanism.…”

Magnetic order of Dy3+ and Fe3+ moments in antiferromagnetic DyHoogeboom1, Kuschel2, Bauer3 et al. 2021Phys. Rev. B17071View full textAdd to dashboardCite

“…Since G c is a smooth function at α = 0, it cannot be held responsible for the large zero-field magnetoresistance. The angular SMR appears to be dominated by the Néel vector G of the Fe moments, in contrast to SmFeO 3 in which the Sm ions determine not only the amplitude but also the sign of the SMR [49].…”

Magnetic order of Dy$^{3+}$ and Fe$^{3+}$ moments in antiferromagnetic DyFeO$_{3}$ probed by spin Hall magnetoresistance and spin Seebeck effect

“…Since, G c is a smooth function at α = 0, it cannot be hold responsible for the large zero-field magnetoresistance. The angular SMR appears to be dominated by the Néel vector G of the Fe moments, in contrast to SmFeO 3 , in which the Sm-ions determine not only the amplitude but also the sign of the SMR [49].…”