Electronic structure of cuprate-nickelate infinite-layer heterostructure

The discovery of superconductivity in Sr/Ca-doped infinite-layer nickelates Nd(La)NiO_(2)thin films inspired extensive experimental and theoretical research.However,research on the possibilities of enhanced critical temperature by interface heterostructure is still lacking.Due to the similarities of the crystal structure and band structure of infinite-layer nickelate La NiO_(2)and cuprate CaCuO_(2),we investigate the crystal,electronic and magnetic properties of La NiO_(2):CaCuO_(2)heterostructure using density functional theory and dynamical mean-field theory.Our theoretical results demonstrate that,even a very weak inter-layer z-direction bond is formed,an intrinsic charge transfer between Cu-3d_(x^(2)-y^(2))and Ni-3d_((x^(2)-y^(2)))orbitals is obtained.The weak interlayer hopping between Cu and Ni leaves a parallel band contributed by Ni/Cu-3d_((x^(2)-y^(2)))orbitals near the Fermi energy.Such an infinite-layer heterostructure with negligible interlayer interaction and robust charge transfer opens a new way for interface engineering and nickelate superconductors.

Thickness-dependent and strain-tunable magnetism in twodimensional van der Waals VSe_(2)

Two-dimensional(2D)van der Waals(vdW)magnetic materials with reduced dimensionality often exhibit unexpected properties compared to their bulk counterparts.In particular,the mechanical flexibility of 2D structure,enhanced ferromagnetism at reduced layer thickness,as well as robust perpendicular magnetic anisotropy are quite appealing for constructing novel spintronic devices.The vdW vanadium diselenide(VSe_(2))is an attractive material whose bulk is paramagnetic while monolayer is ferromagnetic with a Curie temperature(Tc)above room temperature.To explore its possible device applications,a detailed investigation on the thickness-dependent magnetism and strain modulation behavior of VSe_(2)is highly demanded.In this article,the VSe_(2)nanoflakes were controllably prepared via chemical vapor deposition(CVD)method.The few-layer single VSe_(2)nanoflakes were found to exhibit magnetic domain structures at room temperature.Ambient magnetic force microscopy(MFM)phase images reveal a clear thickness-dependent magnetism and the MFM phase contrast is traceable for the nanoflakes of layer thickness below~6 nm.Moreover,applying strain is found efficient in modulating the magnetic moment and coercive field of 2D VSe_(2)at room temperature.These results are helpful for understanding the ferromagnetism of high temperature 2D magnets and for constructing novel straintronic devices or flexible spintronic devices.