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Register a new userTailoring the electronic transitions of NdNiO_3 films through (111)_pc oriented interfaces
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Bulk NdNiO_3 and thin films grown along the pseudocubic (001)_pc axis display a 1st order metal to insulator transition (MIT) together with a Neel transition at T=200K. Here, we show that for NdNiO3 films deposited on (111)_pc NdGaO_3 the MIT occurs at T=335K and the Neel transition at T=230 K. By comparing transport and magnetic properties of layers grown on substrates with different symmetries and lattice parameters, we demonstrate a particularly large tuning when the epitaxy is realized on (111)_pc surfaces. We attribute this effect to the specific lattice matching conditions imposed along this direction when using orthorhombic substrates.
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We report on the electronic structure of $alpha$-Sn films in the very low thickness regime grown on InSb(111)A. High-resolution low photon energies angle-resolved photoemission (ARPES) allows for the direct observation of the linearly dispersing 2D topological surface states (TSSs) that exist between the second valence band and the conduction band. The Dirac point of this TSS was found to be 200meV below the Fermi level in 10-nm-thick $alpha$-Sn films, which enables the observation of the hybridization gap opening at the Dirac point of the TSS for thinner films. The crossover to a quasi-2D electronic structure is accompanied by a full gap opening at the Brillouin zone center, in agreement with our density functional theory calculations. We further identify the thickness regime of $alpha$-Sn films where the hybridization gap in TSS coexists with the topologically non-trivial electronic structure and one can expect the presence of a 1D helical edge states.
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