Search for: All records

We report evidence for superconductivity with onset temperatures up to 11 K in thin films of the infinite-layer nickelate parent compound ${\mathrm{NdNiO}}_2$. A combination of oxide molecular beam epitaxy and atomic hydrogen reduction yields samples with high crystallinity and low residual resistivities, a substantial fraction of which exhibit superconducting transitions. We survey a large series of samples with a variety of techniques, including electrical transport, scanning transmission electron microscopy, x-ray absorption spectroscopy, and resonant inelastic x-ray scattering, to investigate the possible origins of superconductivity. We propose that superconductivity could be intrinsic to the undoped infinite-layer nickelates but suppressed by disorder due to a possibly sign-changing order parameter, a finding which would necessitate a reconsideration of the nickelate phase diagram. Another possible hypothesis is that the parent materials can be hole doped from randomly dispersed apical oxygen atoms, which would suggest an alternative pathway for achieving superconductivity. Published by the American Physical Society2025 

β -Ga2O3 is actively touted as the next ultrawide bandgap material for power electronics. To fully utilize its high intrinsic critical electric field, development of high-quality robust large-barrier height junctions is essential. To this end, various high-work function metals, metal oxides, and hole-conducting oxides have been deposited on Ga2O3, primarily formed by sputter deposition. Unfortunately, reports to date indicate that measured barrier heights often deviate from the Schottky–Mott model as well as x-ray photoelectron spectroscopy (XPS) extractions of conduction band offsets, suggesting significant densities of electrically active defects at these junctions. We report Schottky diodes made from noble metal oxides, IrO2 and RuO2, deposited by ozone molecular beam epitaxy (ozone MBE) with barrier heights near 1.8 eV. These barriers show close agreement across extraction methods and robust to high surface electric fields upward of 6 MV/cm and 60 A/cm2 reverse current without degradation. 

Abstract We report the growth of α -Ga 2 O 3 on m -plane α -Al 2 O 3 by conventional plasma-assisted molecular-beam epitaxy and In-mediated metal–oxide-catalyzed epitaxy (MOCATAXY). We report a growth rate diagram for α -Ga 2 O 3 ( 10 1 ¯ 0 ), and observe (i) a growth rate increase, (ii) an expanded growth window, and (iii) reduced out-of-lane mosaic spread when MOCATAXY is employed for the growth of α -Ga 2 O 3 . Through the use of In-mediated catalysis, growth rates over 0.2 μ m h −1 and rocking curves with full width at half maxima of Δ ω ≈ 0.45° are achieved. Faceting is observed along the α -Ga 2 O 3 film surface and explored through scanning transmission electron microscopy.