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In the fundamental understanding of magnetic interactions between atoms in solids, the crystal lattice is one of the key parameters. As the effective tool for controlling the lattice using tensile stress is limited, there are only few demonstrations of the control in magnetic properties with expanding the lattice structure. Here, we observe that the Curie temperature (Tc) of quasi two-dimensional Cr2Ge2Te6 with NiO overlayer doubles from ~60 K to ~120 K, describe a clear correlation of magnetic properties with lattice expansion, which is characterized by several probes and computational approaches, and address on the mechanisms leading to the increase in Tc via the change in exchange interactions.

Devices based on a pure spin current (a flow of spin angular momentum) have been attracting increasing attention as key ingredients for low-dissipation electronics. To integrate such spintronics devices into charge-based technologies, an electric detection of spin current is essential. Inverse spin Hall effect converts a spin current into an electric voltage through spin-orbit coupling. Noble metals such as Pt and Pd, and also Cu-based alloys, owing to the large direct spin Hall effect, have been regarded as potential materials for a spin-current injector. Those materials, however, are not promising as a spin-current detector based on inverse spin Hall effect. Their spin Hall resistivity rho_SH, representing the performance as a detector, is not large enough mainly due to their low charge resistivity. Here we demonstrate that heavy transition metal oxides can overcome such limitations inherent to metal-based spintronics materials. A binary 5d transition metal oxide IrO2, owing to its large resistivity as well as a large spin-orbit coupling associated with 5d character of conduction electrons, was found to show a gigantic rho_SH ~ 38 microohm cm at room temperature, one order of magnitude larger than those of noble metals and Cu-based alloys and even comparable to those of atomic layer thin film of W and Ta.