102 research outputs found
Epitaxial strain modulated electronic properties of interface controlled nickelate superlattice
Perovskite nickelate heterostructure consisting of single unit cell of
EuNiO and LaNiO have been grown on a set of single crystalline
substrates by pulsed laser interval deposition to investigate the effect of
epitaxial strain on electronic and magnetic properties at the extreme interface
limit. Despite the variation of substrate in-plane lattice constants and
lattice symmetry, the structural response to heterostructuring is primarily
controlled by the presence of EuNiO layer. In sharp contrast to bulk
LaNiO or EuNiO, the superlattices grown under tensile strains exhibit
metal to insulator transition (MIT) below room temperature. The onset of
magnetic and electronic transitions associated with the MIT can be further
separated by application of large tensile strain. Furthermore, these
transitions can be entirely suppressed by very small compressive strain. X-ray
resonant absorption spectroscopy measurements reveal that such
strain-controlled MIT is directly linked to strain induced self-doping effect
without any chemical doping.Comment: Accepted in Phys. Rev.
Epitaxial growth of (111)-oriented LaAlO/LaNiO ultra-thin superlattices
The epitaxial stabilization of a single layer or superlattice structures
composed of complex oxide materials on polar (111) surfaces is severely
burdened by reconstructions at the interface, that commonly arise to neutralize
the polarity. We report on the synthesis of high quality LaNiO/mLaAlO
pseudo cubic (111) superlattices on polar (111)-oriented LaAlO, the
proposed complex oxide candidate for a topological insulating behavior.
Comprehensive X-Ray diffraction measurements, RHEED, and element specific
resonant X-ray absorption spectroscopy affirm their high structural and
chemical quality. The study offers an opportunity to fabricate interesting
interface and topology controlled (111) oriented superlattices based on
ortho-nickelates
Synthesis and electronic properties of Ruddlesden-Popper strontium iridate epitaxial thin films stabilized by control of growth kinetics
We report on the selective fabrication of high-quality SrIrO and
SrIrO epitaxial thin films from a single polycrystalline SrIrO
target by pulsed laser deposition. Using a combination of X-ray diffraction and
photoemission spectroscopy characterizations, we discover that within a
relatively narrow range of substrate temperature, the oxygen partial pressure
plays a critical role in the cation stoichiometric ratio of the films, and
triggers the stabilization of different Ruddlesden-Popper (RP) phases. Resonant
X-ray absorption spectroscopy measurements taken at the Ir -edge and the O
-edge demonstrate the presence of strong spin-orbit coupling, and reveal the
electronic and orbital structures of both compounds. These results suggest that
in addition to the conventional thermodynamics consideration, higher members of
the SrIrO series can possibly be achieved by kinetic
control away from the thermodynamic limit. These findings offer a new approach
to the synthesis of ultra-thin films of the RP series of iridates and can be
extended to other complex oxides with layered structure.Comment: 7 pages, 6 figure
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