A5071916504- Physics of Superconductivity and Magnetism
- Magnetic and transport properties of perovskites and related materials
- Advanced Condensed Matter Physics
- Electronic and Structural Properties of Oxides
- Organic and Molecular Conductors Research
- Multiferroics and related materials
- Superconducting Materials and Applications
- Magnetic properties of thin films
- 2D Materials and Applications
- Iron-based superconductors research
- Ferroelectric and Piezoelectric Materials
- Inorganic Fluorides and Related Compounds
- Superconducting and THz Device Technology
- Advanced Physical and Chemical Molecular Interactions
- Transition Metal Oxide Nanomaterials
- Advanced Chemical Physics Studies
- Superconductivity in MgB2 and Alloys
- Copper-based nanomaterials and applications
- Semiconductor materials and devices
- Quantum and electron transport phenomena
- Methane Hydrates and Related Phenomena
- Machine Learning in Materials Science
- Spacecraft and Cryogenic Technologies
- Chemical and Physical Properties of Materials
- Spectroscopy and Quantum Chemical Studies
Max Planck Institute for Solid State Research
2017-2024
Temple University
2024
Sungkyunkwan University
2023
Institute for Basic Science
2015-2018
Seoul National University
2015-2018
Abstract In high-energy physics, the Higgs field couples to gauge bosons and fermions gives mass their elementary excitations. Experimentally, such couplings can be inferred from decay product of boson, i.e., scalar (amplitude) excitation field. superconductors, Cooper pairs bear a close analogy Interaction between other degrees freedom provides dissipation channels for amplitude mode, which may reveal important information about microscopic pairing mechanism. To this end, we investigate...
Ultrafast optical control of quantum systems is an emerging field physics. In particular, the possibility light-driven superconductivity has attracted much attention. To identify nonequilibrium superconductivity, it necessary to measure fingerprints on ultrafast timescales. Recently, nonlinear THz third-harmonic generation (THG) was shown directly probe collective degrees freedoms superconducting condensate, including Higgs mode. Here, we extend this idea states in La
Abstract Cuprate high- T c superconductors are known for their intertwined interactions and the coexistence of competing orders. Uncovering experimental signatures these is often first step in understanding complex relations. A typical spectroscopic signature interaction between a discrete mode continuum excitations Fano resonance/interference, characterized by asymmetric light-scattering amplitude as function electromagnetic driving frequency. In this study, we report new type resonance...
Topological transport phenomena in magnetic materials are a major topic of current condensed matter research. One the most widely studied is ``topological Hall effect'' (THE), which generated via spin-orbit interactions between conduction electrons and topological spin textures such as skyrmions. We report comprehensive set effect magnetization measurements on epitaxial films prototypical ferromagnetic metal SrRuO$_3$ properties were systematically modulated by varying concentration Ru...
Barium bismuth oxide (BaBiO_{3}) is the end member of two families high-T_{c} superconductors, i.e., BaPb_{1-x}Bi_{x}O_{3} and Ba_{1-x}K_{x}BiO_{3}. The undoped parent compound an insulator, exhibiting a charge density wave that strongly linked to static breathing distortion in oxygen sublattice perovskite structure. We report comprehensive spectroscopic x-ray diffraction study BaBiO_{3} thin films, showing minimum film thickness required stabilize ≈11 unit cells, both phenomena are...
$2H\text{-NbS}{\mathrm{e}}_{2}$ is an archetypal system in which superconductivity and charge density wave (CDW) coexist compete macroscopically with each other. In particular, this interplay also manifests their dynamical fluctuations. As a result, the superconducting amplitude fluctuation (i.e., Higgs mode) pushed below quasiparticle continuum, allowing it to become coherent excitation observable by Raman scattering. present study, we coherently drive collective oscillations of two orders...
The superconducting properties of high-${T}_{c}$ materials are functions the concentration charge carriers, which is controlled by defects including heterovalent cations, interstitial oxygen ions, and vacancies. Here we combine low-temperature thermal treatment ${\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{CuO}}_{4}$ epitaxial thin films confocal Raman spectroscopy to control investigate We demonstrate that apical site most favorable position accommodate vacancies under...
Significance Chemical substitution is widely used to modify the charge-carrier concentration (“doping”) in complex quantum materials, but influence of associated structural disorder on electronic phase behavior remains poorly understood. We synthesized thin films high-temperature superconductor <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">L</mml:mi> mathvariant="normal">a</mml:mi> </mml:mrow> <mml:mn>2</mml:mn>...
The synthesis of stoichiometric ${\mathrm{Sr}}_{2}{\mathrm{RuO}}_{4}$ thin films has been a challenge because the high volatility ruthenium oxide precursors, which gives rise to vacancies in films. Ru greatly affect transport properties and electronic phase behavior ${\mathrm{Sr}}_{2}{\mathrm{RuO}}_{4}$, but their direct detection is difficult due atomic dimensions low concentration. We applied polarized x-ray absorption spectroscopy at oxygen $K$ edge confocal Raman synthesized under...
Strain engineering of complex oxide heterostructures has provided routes to explore the influence local perturbations physical properties material. Due challenge disentangling intrinsic and extrinsic effects at interfaces, combined epitaxial strain charge transfer mechanisms have been rarely studied. Here, we reveal distribution in manganite slabs by means high-resolution electron microscopy spectroscopy via investigating how locally alters electronic magnetic La0.5Sr0.5MnO3-La2CuO4...
Abstract Charge Density Waves (CDW) are commonly associated with the presence of near-Fermi level states which separated from others, or “nested", by a wavector q . Here we use Angle-Resolved Photo Emission Spectroscopy (ARPES) on CDW material Ta 2 NiSe 7 and identify total absence any plausible nesting at primary wavevector Nevertheless observe spectral intensity replicas hole-like valence bands, shifted , appears transition. In contrast, find that there is possible 2q associate characters...
We report a polarized Raman scattering study of the lattice dynamics $\beta$-Li$_2$IrO$_3$ under hydrostatic pressures up to 7.62 GPa. At ambient pressure, exhibits hyperhoneycomb crystal structure and magnetically ordered state spin-orbit entangled Jeff = 1/2 moments that is strongly influenced by bond-directional (Kitaev) exchange interactions. critical pressure ~ 4.1 GPa, phonon spectrum changes abruptly consistent with reported structural transition into monoclinic, dimerized phase. A...
Co4Ta2O9 exhibits a three-dimensional magnetic lattice based on the buckled honeycomb motif. It shows unusual magnetoelectric effects, including sign change and non-linearity. These effects cannot be understood without detailed knowledge of structure. Herein, we report neutron diffraction direction-dependent susceptibility measurements single crystals. Below 20.3 K, find long-range antiferromagnetic order in alternating flat layers Co2+ ions stacked along c axis. Within experimental...
The exchange bias effect is an essential component of magnetic memory and spintronic devices. Whereas recent research has shown that anisotropies perpendicular to the device plane provide superior stability against thermal noise, it proven remarkably difficult realize in thin-film structures. Here we demonstrate a strong heterostructures quasi-two-dimensional canted antiferromagnet ${\mathrm{La}}_{2}{\mathrm{CuO}}_{4}$ ferromagnetic $(\mathrm{La},\mathrm{Sr}){\mathrm{MnO}}_{3}$ synthesized...
We have investigated the structural, magnetic and superconduction properties of [Nb(1.5 nm)/Fe( x )] 10 superlattices deposited on a thick Nb(50 nm) layer. Our investigation showed that layer grows epitaxially at 800 °C Al 2 O 3 (1−102) substrate. Samples grown this condition possess high residual resistivity ratio 15–20. By using neutron reflectometry we show Fe/Nb with < 4 nm form depth-modulated FeNb alloy concentration iron varying between 60% 90%. This has weak ferromagnetic...
The nondestructive investigation of electronic and magnetic modifications at buried interfaces contributes significantly to the understanding underlying interactions. This knowledge is essential for design devices based on complex quantum materials. Herein, application resonant X‐ray neutron reflectometry study perovskite transition metal oxide heterostructures reviewed. Both methods are well suited interfacial reconstructions interactions spin, charge, orbitals nanoscale. cases highlighted...
<title>Abstract</title> The perovskite ABO3 structure forms the basis for a wide range of functional and quantum materials discussed in literature, although applications so far have been limited part because accurate control film stoichiometry ability to precisely construct heterostructures continues lag behind their conventional semiconductor counterparts. While layer-by-layer growth mode is often cited films, most transition-metal oxides self-assemble via an energetically-favorable...
Despite decades of search for the pairing boson in cuprate high-Tc superconductors, its identity still remains debated to date. For this reason, spectroscopic signatures electron-boson interactions cuprates have always been a center attention. example, kinks quasiparticle dispersion observed by angle-resolved photoemission spectroscopy (ARPES) studies motivated decade-long investigation electron-phonon as well electron-paramagnon cuprates. On other hand, overlap between charge-order...
Devices with tunable magnetic noncollinearity are important components of superconducting electronics and spintronics, but they typically require epitaxial integration several complex materials. The spin-polarized neutron reflectometry measurements on La1-x Srx MnO3 homojunction arrays modulated Sr concentration reported herein have led to the discovery fan structures highly noncollinear alignment Mn spins an emergent periodicity twice as large array's unit cell. data show that these...
Strongly correlated materials with multiple order parameters provide unique insights into the fundamental interactions in condensed matter systems and present opportunities for innovative technological applications. A class of antiferromagnetic honeycomb lattices compounds, A4B2O9 (A = Co, Fe, Mn; B Nb, Ta), have been explored owing to occurrence linear magnetoelectricity. We observe a highly nonlinear magnetoelectric effect on single crystals Co4Ta2O9 (CTO), distinctive from behavior...