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The Dzyaloshinskii-Moriya interaction (DMI) at the heavy metal (HM) and ferromagnetic metal (FM) interface has been recognized as a key ingredient in spintronic applications. Here we investigate the chemical trend of DMI on the 5d band filling (5d³-5d10) of the HM element in HM/FM (FM=CoFeB,Co)/MgO multilayer thin films. DMI is quantitatively evaluated by measuring asymmetric spin wave dispersion using Brillouin light scattering. Sign reversal and 20 times modification of the DMI coefficient D have been measured as the 5d HM element is varied. The chemical trend can be qualitatively understood by considering the 5d and 3d bands alignment at the HM/FM interface and the subsequent orbital hybridization around the Fermi level. Furthermore, a correlation is observed between DMI and effective spin mixing conductance at the HM/FM interfaces. Our results provide new insights into the interfacial DMI for designing future spintronic devices. [ABSTRACT FROM AUTHOR]

In this Letter, we report the observation of thermally induced rotation of graphene on hexagonal boron nitride (h-BN). After the rotation, two thermally stable configurations of graphene on h-BN with a relative lattice twisting angle of 0° (most stable) and 30° (metastable), respectively, were found. Graphene on h-BN with a twisting angle below (above) a critical angle of ~12±2° tends to rotate towards 0° (30°) at a temperature of >100°C, which is in line with our theoretical simulations. In addition, by manipulating the annealing temperature and the flake sizes of graphene, moiré superlattices with large spatial periods of graphene on h-BN are achieved. Our studies provide a detailed understanding of the thermodynamic properties of graphene on h-BN and a feasible approach to obtaining van der Waals heterostructures with aligned lattices. [ABSTRACT FROM AUTHOR]