A5028381983- Magnetic and transport properties of perovskites and related materials
- Advanced Condensed Matter Physics
- Electronic and Structural Properties of Oxides
- Physics of Superconductivity and Magnetism
- Multiferroics and related materials
- Ferroelectric and Piezoelectric Materials
- Topological Materials and Phenomena
- Muon and positron interactions and applications
- Inorganic Chemistry and Materials
- Advanced NMR Techniques and Applications
- Semiconductor materials and devices
- Rare-earth and actinide compounds
- Acoustic Wave Resonator Technologies
- Advanced Memory and Neural Computing
- Nuclear materials and radiation effects
- Graphene research and applications
- Copper-based nanomaterials and applications
- ZnO doping and properties
- Magnetic properties of thin films
- Catalysis and Oxidation Reactions
- Advanced ceramic materials synthesis
- Transition Metal Oxide Nanomaterials
- Theoretical and Computational Physics
- Magnetism in coordination complexes
- Microwave Dielectric Ceramics Synthesis
Rutgers, The State University of New Jersey
2016-2025
Rutgers Sexual and Reproductive Health and Rights
2020
Rütgers (Germany)
2020
Indian Institute of Science Bangalore
2019
University of Arkansas at Fayetteville
2008-2017
Nanyang Technological University
2013
Astronomy and Space
2008-2011
Max Planck Institute for Solid State Research
2005-2007
Argonne National Laboratory
2007
Northern Illinois University
2007
Orbital reconstructions and covalent bonding must be considered as important factors in the rational design of oxide heterostructures with engineered physical properties. We have investigated interface between high-temperature superconducting (Y,Ca)Ba 2 Cu 3 O 7 metallic La 0.67 Ca 0.33 MnO by resonant x-ray spectroscopy. A charge about –0.2 electron is transferred from Mn to ions across induces a major reconstruction orbital occupation symmetry interfacial CuO layers. In particular, d z – r...
Finding new collective electronic states in materials is one of the fundamental goals condensed matter physics. Atomic-scale superlattices formed from transition metal oxides are a particularly appealing hunting ground for In bulk form, exhibit remarkable range magnetic, superconducting, and multiferroic phases that great scientific interest potentially capable providing innovative energy, security, electronics medical technology platforms. may emerge at interfaces where dissimilar meet....
Using resonant X-ray spectroscopies combined with density functional calculations, we find an asymmetric bi-axial strain-induced $d$-orbital response in ultra-thin films of the correlated metal LaNiO$_3$ which are not accessible bulk. The sign misfit strain governs stability octahedral "breathing" distortion, which, turn, produces emergent charge-ordered ground state altered ligand-hole and bond covalency. Control this new mechanism opens a pathway to rational orbital engineering, providing...
The electronic structure of transition metal oxides featuring correlated electrons can be rationalized within the Zaanen-Sawatzky-Allen framework. Following a brief description present paradigms behavior, we focus on physics rare-earth nickelates as an archetype complexity emerging charge transfer regime. intriguing prospect realizing high-T c cuprates through heterostructuring resulted in massive endeavor to epitaxially stabilize these materials ultrathin form. A plethora new phenomena...
We investigate the electronic reconstruction in (LaNiO$_{3}$)$_n$/(LaAlO$_{3}$)$_3$ (n=3, 5 and 10) superlattices due to quantum confinement (QC) by d.c. transport resonant soft x-ray absorption spectroscopy. In proximity QC limit, a Mott-type transition from an itinerant electron behavior localized state is observed. The system exhibits tendency towards charge-order during transition. ab initio cluster calculations are good agreement with spectra, indicating that apical ligand hole density...
Pyrochlore materials are known for their exotic magnetic and topological phases arising from complex interactions among electron correlations, band topology, geometric frustration. Interfaces between different pyrochlore crystals characterized by many-body ground states hold immense potential novel interfacial phenomena due to the strong these phases. However, realization of such interfaces has been severely hindered limitations in material synthesis methods. In this study, we discover a...
Multilayers of superconducting/ferromagnetic (SC/FM) ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7}∕{\mathrm{La}}_{2∕3}{\mathrm{Ca}}_{1∕3}{\mathrm{MnO}}_{3}$ have been studied by neutron reflectometry. The occurrence a structurally forbidden Bragg peak in the FM state highlights significant difference between nuclear and magnetic depth profiles. From comparison with simulated reflectivity curves we identify two possible magnetization profiles: (i) moment within SC layer antiparallel to...
We have synthesized epitaxial NdNiO$_{3}$ ultra-thin films in a layer-by-layer growth mode under tensile and compressive strain on SrTiO$_{3}$ (001) LaAlO$_3$ (001), respectively. A combination of X-ray diffraction, temperature dependent resistivity, soft absorption spectroscopy has been applied to elucidate electronic structural properties the samples. In contrast bulk NdNiO$_{3}$, metal-insulator transition is found be completely quenched, while remains albeit modified from behavior.
In pursuit of rational control orbital polarization, we present a combined experimental and theoretical study single-unit-cell superlattices the correlated metal LaNiO3 band insulator LaAlO3. Polarized X-ray absorption spectra show distinct asymmetry in response under strain. A splitting energies consistent with octahedral distortions is found for case compressive sharp contrast, tensile strain, no although strong polarization present. Density functional theory calculations including Hubbard...
An optical study of NdNiO(3) ultrathin films with insulating and metallic ground states reveals new aspects the insulator-to-metal transition that point to Mott physics as driving force. In contrast behavior charge-ordered systems, we find emergence Drude resonance across is linked a spectral weight transfer over an energy range order Coulomb repulsion U, gap filled instead closing continuously.
Polar metals, commonly defined by the coexistence of polar crystal structure and metallicity, are thought to be scarce because long-range electrostatic fields favoring expected fully screened conduction electrons a metal. Moreover, reducing from three two dimensions, it remains an open question whether metal can exist. Here we report on realization room temperature two-dimensional B-site type in tri-color (tri-layer) superlattices BaTiO$_3$/SrTiO$_3$/LaTiO$_3$. A combination atomic...
By using an alternative wet-etch procedure, we have obtained high-quality atomically flat TiO2 terminated surfaces of SrTiO3 single crystals with the morphology equivalent to that conventional methods. applying a combined power photoluminescence (PL) spectroscopy, reflection high-energy electron diffraction, atomic force microscopy imaging, and soft x-ray absorption (XAS), were able identify monitor complex evolution oxygen defect states Ti valency at surface near-surface layers. Our...
An optical study of fully strained ultrathin ${\mathrm{LaNiO}}_{3}$ films is presented and compared with LDA + DMFT calculations. were grown by pulsed laser deposition on ${\mathrm{LaAlO}}_{3}$ ${\mathrm{SrTiO}}_{3}$ substrates which provide compressive tensile strain, respectively. Optical conductivity data show a Drude peak spectral weight that significantly reduced to obtained from The extended analysis reveals the presence pseudogap around 80 meV for film near 40 meV, at low temperature...
We address the fundamental issue of growth perovskite ultra-thin films under condition a strong polar mismatch at heterointerface exemplified by correlated metal LaNiO3 on band insulator SrTiO3 along pseudo cubic [111] direction. While in general metallic film can effectively screen this polarity mismatch, we establish that limit, are insulating nature and require additional chemical structural reconstruction to compensate for such mismatch. A combination in-situ reflection high-energy...
Deterministic control over the periodic geometrical arrangement of constituent atoms is backbone material properties, which, along with interactions, define electronic and magnetic ground state. Following this notion, a bilayer prototypical rare-earth nickelate, NdNiO_{3}, combined dielectric spacer, LaAlO_{3}, has been layered pseudocubic [111] direction. The resulting artificial graphenelike Mott crystal 3d electrons antiferromagnetic correlations. In addition, combination resonant X-ray...
A novel high magnetic field (8 T) spectrometer for muon spin rotation has been used to measure the temperature dependence of in-plane penetration depth ${\ensuremath{\lambda}}_{\mathrm{ab}}$ in ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{6.95}$. At low $H$ and $T$, exhibits characteristic linear $T$ associated with energy gap a ${d}_{{x}^{2}{\ensuremath{-}y}^{2}}$-wave superconductor. However, at higher fields is essentially independent $T$. We discuss possible interpretations this...
Resonant x-ray diffraction performed at the L(II) and L(III) absorption edges of Ru has been used to investigate magnetic orbital ordering in Ca2RuO4 single crystals. A large resonant enhancement due electric dipole 2p-->4d transitions is observed wave-vector characteristic antiferromagnetic ordering. Besides previously known phase transition T(N)=110 K, an additional transition, between two paramagnetic phases, around 260 K. Based on polarization azimuthal angle dependence signal, this can...
A combination of spectroscopic probes was used to develop a detailed experimental description the transport and magnetic properties superlattices composed paramagnetic metal CaRuO$_3$ antiferromagnetic insulator CaMnO$_3$. The charge carrier density Ru valence state in are not significantly different from those bulk CaRuO$_3$. small transfer across interface implied by these observations confirms predictions derived functional calculations. However, ferromagnetic polarization due canted Mn...
The perovskite SrIrO_{3} is an exotic narrow-band metal owing to a confluence of the strengths spin-orbit coupling (SOC) and electron-electron correlations. It has been proposed that topological magnetic insulating phases can be achieved by tuning SOC, Hubbard interactions, and/or lattice symmetry. Here, we report substitution nonmagnetic, isovalent Sn^{4+} for Ir^{4+} in SrIr_{1-x}Sn_{x}O_{3} perovskites synthesized under high pressure leads metal-insulator transition antiferromagnetic (AF)...
Transition metal oxides are complex electronic systems that exhibit a multitude of collective phenomena. Two archetypal examples VO 2 and NdNiO 3 , which undergo metal–insulator phase transition (MIT), the origin is still under debate. Here this study reports discovery memory effect in both systems, manifested through an increase resistance at specific temperature, set by reversing temperature ramp from heating to cooling during MIT. The characteristics ramp‐reversal do not coincide with any...