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Interfacial magnetic anisotropy in magnetic insulators has been largely unexplored. Recently, interface-induced skyrmions and electrical control of magnetization have been discovered in insulator-based heterostructures, which demand a thorough understanding of interfacial interactions in these materials. We observe a substantial, tunable interfacial magnetic anisotropy between Tm_{3}Fe_{5}O_{12} epitaxial thin films and fifteen nonmagnetic materials spanning a significant portion of the periodic table, which we attribute to Rashba spin-orbit coupling. Our results show a clear distinction between nonmagnetic capping layers from the d block and the p block. This work offers a new path for controlling magnetic phases in magnetic insulators for low-loss spintronic applications.

We demonstrate nondecaying, steplike electrical switching of tristate N\'eel order in $\mathrm{Pt}/\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$ bilayers detected by the spin-Hall induced anomalous Hall effect. The as-grown $\mathrm{Pt}/\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$ bilayers exhibit sawtooth switching behavior generated by current pulses. After annealing by a high pulse current, the Hall signals reveal single-pulse saturated, nondecaying, steplike switching. Together with control experiments, we show that the sawtooth switching is due to an artifact of Pt while the actual spin-orbit torque induced antiferromagnetic switching is steplike. Our Monte Carlo simulations explain the switching behavior of $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$ N\'eel order among three in-plane easy axes.

The topological Hall effect has been a primary indicator of nontrivial spin textures in magnetic materials. We observe the evidence of the topological Hall effect in $\mathrm{Pt}/{\mathrm{Cr}}_{2}{\mathrm{O}}_{3}$ bilayers grown on ${\mathrm{Al}}_{2}{\mathrm{O}}_{3}(0001)$ and ${\mathrm{Al}}_{2}{\mathrm{O}}_{3}(11\overline{2}0)$, where the ${\mathrm{Cr}}_{2}{\mathrm{O}}_{3}$ epitaxial film is an antiferromagnetic insulator. The $\mathrm{Pt}/{\mathrm{Cr}}_{2}{\mathrm{O}}_{3}$ bilayers exhibit topological Hall resistivity for ${\mathrm{Cr}}_{2}{\mathrm{O}}_{3}$ thicknesses below 6 nm near and above room temperature, which is above the N\'eel temperature of ${\mathrm{Cr}}_{2}{\mathrm{O}}_{3}$, revealing the key role of thermal fluctuations in the formation of spin textures. The similarity of topological Hall signals in (0001)- and $(11\overline{2}0)$-oriented ${\mathrm{Cr}}_{2}{\mathrm{O}}_{3}$ films indicates that the emergence of spin textures is insensitive to crystalline orientation.

We report spin-echo double resonance NMR measurements of {sup 17}O- {sup 63} Cu indirect (electron-mediated) nuclear spin-spin coupling between Cu and O atoms in the CuO{sub 2} planes of YBa{sub 2}Cu {sub 3}O{sub 7} . The magnitude of the measured coupling is anomalously large, to the extent that it is inconsistent with the antiferromagnetic correlations that are invoked to explain the contrasting T{sub 1} behaviors of {sup 63}Cu and {sup 17}O . {copyright} {ital 1999} {ital The American Physical Society }

We report a simple NMR experiment measuring individual ${}^{63}\mathrm{Cu}\ensuremath{-}{}^{63}\mathrm{Cu}$ indirect nuclear coupling frequencies in $\mathrm{YBa}{}_{2}\mathrm{Cu}{}_{3}{\mathrm{O}}_{7}$. We show that the coupling interaction at $T\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}5\mathrm{K}$ is of quite short range, indicating an anitferromagnetic correlation length $\ensuremath{\xi}$ of $\ensuremath{\sim}1$ lattice constant or less.

A priori theoretical considerations lead one to expect that ${\mathrm{Rb}}_{3}{\mathrm{C}}_{60}$ is a Mott-Hubbard insulator. This has led to the proposal that the superconductor `` ${\mathrm{Rb}}_{3}{\mathrm{C}}_{60}$'' is, in fact, ${\mathrm{Rb}}_{3\ensuremath{-}\ensuremath{\varepsilon}}{\mathrm{C}}_{60}$ $(\ensuremath{\varepsilon}\ensuremath{\sim}0.06)$, and, furthermore, that the vacancies are associated with an unexpected, robust splitting in ${}^{87}\mathrm{Rb}$ NMR. We demonstrate that vacancies, if present, are unrelated to observed NMR splittings.