40 research outputs found
Fabrication of (111)-oriented Ca0.5Sr0.5IrO3/SrTiO3 superlattices; a designed playground for honeycomb physics
We report the fabrication of (111)-oriented superlattice structures with
alternating 2m-layers (m = 1, 2, and 3) of Ca0.5Sr0.5IrO3 perovskite and two
layers of SrTiO3 perovskite on SrTiO3(111) substrates. In the case of m = 1
bilayer films, the Ir sub-lattice is a buckled honeycomb, where a topological
state may be anticipated. The successful growth of superlattice structures on
an atomic level along the [111] direction was clearly demonstrated by
superlattice reflections in x-ray diffraction patterns and by
atomically-resolved transmission electron microscope images. The ground states
of the superlattice films were found to be magnetic insulators, which may
suggest the importance of electron correlations in Ir perovskites in addition
to the much discussed topological effects.Comment: 14 pages, 4 figure
The emergence of superconductivity in BaNi2(Ge1-xPx)2 at a structural instability
The physical properties and structural evolution of the 122-type solid
solution BaNi2(Ge1-xPx)2 are reported. The in-plane X-X (X = Ge1-xPx) dimer
formation present in the end member BaNi2Ge2, which results in a structural
transition to orthorhombic symmetry, is completely suppressed to zero
temperature on P substitution near x = 0.7, and a dome-shape superconducting
phase with a maximum Tc = 2.9 K emerges. Clear indications of phonon softening
and enhanced electron-phonon coupling are observed at the composition of the
structural instability. Our findings show that dimer breaking offers new
possibilities as a tuning parameter of superconductivity.Comment: 14 pages, 4 figure