A5052152645- Multiferroics and related materials
- Magnetic and transport properties of perovskites and related materials
- Advanced Condensed Matter Physics
- X-ray Diffraction in Crystallography
- Magneto-Optical Properties and Applications
- Electronic and Structural Properties of Oxides
- X-ray Spectroscopy and Fluorescence Analysis
- High-pressure geophysics and materials
- Ferroelectric and Piezoelectric Materials
- Physics of Superconductivity and Magnetism
- Corneal Surgery and Treatments
- Quantum optics and atomic interactions
- Crystallization and Solubility Studies
- Electron and X-Ray Spectroscopy Techniques
- Corneal surgery and disorders
- Photonic Crystals and Applications
- Solid-state spectroscopy and crystallography
- Quantum Chromodynamics and Particle Interactions
- Quantum and electron transport phenomena
- Perovskite Materials and Applications
- Transition Metal Oxide Nanomaterials
- 2D Materials and Applications
- Metamaterials and Metasurfaces Applications
- Crystal Structures and Properties
- Magnetic properties of thin films
Tohoku University
2015-2024
Japan Science and Technology Agency
2005-2024
Spintronics Research Network of Japan
2022-2024
ETH Zurich
2012-2016
University of Bonn
2010-2012
National Institute of Advanced Industrial Science and Technology
2004-2011
Minamiaoyama Eye Clinic
2010
The University of Tokyo
1998-2009
Helsinki Institute of Physics
2006-2008
Tokyo University of Science
2008
Visualizing ferroelectric domains Multiferroic materials support intertwined ferromagnetic and orders, with the magnetic field capable of controlling electric order vice versa. Matsubara et al. used second harmonic generation microscopy to visualize what happens in multiferroic TbMnO 3 when an externally applied changes direction polarization by 90°. Unexpectedly, domain walls, initially parallel vector, did not change their shape or position. The resulting transition from neutral charged...
Abstract Multiferroics and magnetoelectrics with coexisting coupled multiple ferroic orders are materials promising new technological advances. While most studies have focused on single-phase or heterostructures of inorganic materials, a class called metal–organic frameworks (MOFs) has been recently proposed as candidate demonstrating interesting routes for multiferroism magnetoelectric coupling. Herein, we report the origin multiferroicity (CH 3 ) 2 NH Mn(HCOO) via direct observation...
Abstract The control of the optoelectronic properties 2D organic–inorganic hybrid perovskite (2D‐OIHP) lead halides is an increasingly prevalent topic. Herein, observation circular photogalvanic effect (CPGE) in new enantiomorphic 2D‐OIHP iodides reported, which are synthesized as a first OIHP‐related system belonging to chiral space group by incorporating organic cations into inorganic layers iodides. CPGE phenomenon associated with spin–orbit coupling heavy atoms noncentrosymmetric...
The optical magnetoelectric (ME) effect, i.e., the change of absorption upon reversal light propagation direction, has been investigated for a polar ferrimagnet GaFeO3. For dipole- and spin-forbidden d-d transition bands located at 1.2-2.3 eV, clear signal ME effect (Deltaalphat approximately 3x10(-3)) is observed with an applied magnetic field as low 500 Oe sample thickness (t) 50 microm. observation large in present compound suggests possible route to magnification this novel phenomenon...
We report inelastic x-ray scattering studies of charge excitations in insulating ${\mathrm{Nd}}_{2}{\mathrm{CuO}}_{4}$ as a function incident photon energy. An excitation $\ensuremath{\sim}6\mathrm{eV}$ is observed when the energy tuned through Cu $K$ edge. This interpreted resonantly enhanced scattering. Numerical calculations identify 6 eV feature charge-transfer to antibonding state and suggest that nonlocal effects play role determining shape resonance.
We have investigated the ultrafast spin and charge dynamics in course of a photoinduced phase transition from an insulator with short-range order orbital (OO) to ferromagnetic metal perovskite-type Gd0.55Sr0.45MnO3. Transient reflectivity changes suggest that metallic state is formed just after photoirradiation decays within approximately 1 ps. The magnetization, however, increases time constant 0.5 ps 10 relatively slow increase magnetization attributable magnetic-field-induced alignment...
Interest in manipulating the magnetic order by ultrashort laser pulses has thrived since it was observed that such can be used to alter magnetization on a sub-picosecond timescale. Usually this involves demagnetization heating or, rare cases, transient increase of magnetization. Here we demonstrate mechanism allows material enhanced or attenuated at will. This is possible systems simultaneously possessing low, tunable density conduction band carriers and high moments. In systems,...
Abstract Some rodlike organic molecules exhibit exceptionally high layered crystallinity when composed of a link between π‐conjugated backbone (head) and alkyl chain (tail). These are aligned side‐by‐side unidirectionally to form self‐organized polar monomolecular layers, providing promising 2D materials devices. However, their interlayer stacking arrangements have never been tunable, preventing the unidirectional in whole crystals. Here, it is demonstrated that polar/antipolar can be...
Polarization dependence of soft-x-ray Raman scattering was investigated at the Ti $2p$ absorption edge ${\mathrm{TiO}}_{2}.$ Strong feature appears about 14 eV below elastic peaks with strong polarization dependence. These structures are charge transfer excitations to antibonding state between ${3d}^{1}{L}^{\ensuremath{-}1}$ and ${3d}^{0}$ states, because they enhanced when incident photon energies tuned satellite spectrum. Broad found 3 10 peaks. They assigned be nonbonding type or...
Resonant inelastic x-ray scattering (RIXS) at the L2,3 edges of 3d transition metal compounds has recently become a high resolution spectroscopic technique thanks to improvements in instrumentation. We have chosen prototypical case NiO explore various levels interpretation applicable L3 RIXS spectra strongly correlated electron systems. Starting from set experimental data measured across Ni absorption edge with 550 meV combined energy resolution, we analyse rich spectral structure within an...
Differential cross sections for transitions of known weak strength were measured with the (3He, t) reaction at 420 MeV on targets 12C, 13C, 18O, 26Mg, 58Ni, 60Ni, 90Zr, 118Sn, 120Sn, and 208Pb. Using these data, it is shown that proportionalities between strengths this probe follow simple trends as a function mass number. These can be used to confidently determine Gamow-Teller distributions in nuclei which proportionality cannot calibrated via β-decay strengths. Although theoretical...
The resonant inelastic x-ray scattering (RIXS) of $\mathrm{MnO}$ measured with high energy resolution across the ${\mathrm{L}}_{2,3}$ absorption edges Mn is characterized by a very rich spectral structure due to local electronic excitations. spectra are dominated dd and charge transfer excitations, both dipole allowed in RIXS process. strongly depend on polarization incident photons. This vast experimental basis allows an accurate determination main parameters theoretical models used...
Photoinduced effect in a ferromagnetic perovskite ${\mathrm{La}}_{0.6}{\mathrm{Sr}}_{0.4}{\mathrm{MnO}}_{3}$ was investigated by femtosecond pump-probe spectroscopy. By utilizing magneto-optical Kerr rotation as probe, the photoinduced dynamics of spins observed independently quasiparticle relaxation dynamics. The low-energy optical conductivity decreases immediately after photoexcitation without changing magnetization, and subsequently demagnetization occurs strongly temperature-dependent...
We report on the first observation of magnetoelectric X-ray scattering (MEXS), i.e., incident- k -direction-dependent scattering, for a polar ferrimagnet GaFeO 3 . Near K edge Fe, magnetic component (040) reflection shows larger enhancement than that (020) reflection, which cannot be attributed to genuine but MEXS Fe 3+ ions. Toroidal moments as defined by outer product off-center displacement and moment show ferroic ordering, causes resonant at 1 s –3 d excitation energy.
A simple method to dramatically enhance the optical magnetoelectric (ME) effect, i.e., nonreciprocal directional birefringence, is proposed and demonstrated for a polar ferrimagnet ${\mathrm{GaFeO}}_{3}$ as typical example. We patterned grating with period of $4\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$ on surface crystal used diffracted light probe. The ME modulation signal Bragg spot order $n=1$ becomes gigantic in photon energy 1--4 eV reaches 1--2% bare intensity magnetic field 500 Oe....
We investigated the ultrafast dynamics of photoinduced melting charge and orbital order in a perovskite-type manganite, ${\text{Nd}}_{0.5}{\text{Ca}}_{0.5}{\text{MnO}}_{3}$, by means pump-probe reflection spectroscopy. By irradiation with 20-fs laser pulse, only sectors become melted within $\ensuremath{\sim}30\text{ }\text{fs}$ through strong electron correlations. During this process oxygen displacements associated ordered phase persist. These are subsequently released accompanied several...
Photoinduced switching in perovskite manganites by irradiation of a femtosecond laser pulse was investigated on ${\mathrm{Pr}}_{0.55}{({\mathrm{Ca}}_{1\ensuremath{-}y}{\mathrm{Sr}}_{y})}_{0.45}\mathrm{Mn}{\mathrm{O}}_{3}$ locating the critical region between charge and orbital ordered insulator (CO/OOI) phase ferromagnetic metal (FM) phase. For low excitation density, order is partially melted microscopic quasi-FM domains are generated, which rapidly return to CO/OOI state. When density...
Persistent ferromagnetic magnetization (M) as large 0.6 μB per Mn site can be induced by irradiating visible laser pulses on a thin film of 1% Cr-doped Pr0.5Ca0.5MnO3. The enhancement M upon the photoexcitation was also confirmed scanning superconducting quantum interference device microscope an increase magnetic field from domains. observed photoinduced transition metastable charge/orbital ordered state into one is likely to assisted microscopic phase separation characteristic such relaxor...
Resonant inelastic x-ray scattering (RIXS) measurements performed jointly across the ${M}_{2,3}$ and ${L}_{3}$ absorption thresholds are used to study CoO local electronic structure supported by model calculations. The high-resolution experimental data provide a precise set of parameters describe correlated response valence electrons. same core-hole independent within single impurity Anderson is both $M$ $(3p\text{\ensuremath{-}}3d)$ $L$ $(2p\text{\ensuremath{-}}3d)$ resonances. This work...
Pronounced magnetic-dipole-induced second-harmonic generation (SHG) is observed in epitaxial films of the ferromagnetic semiconductor EuO. The SHG light wave emerges background-free at Curie temperature and couples linearly to spontaneous magnetization. spectrum determined by spin-allowed spin-forbidden transitions between $4f$ ground state $5d({t}_{2g})$ states ${\text{Eu}}^{2+}$ ion. At coercive field, components magnetization perpendicular applied field are observed. Spatially resolved...
Abstract Future spintronics and quantum technologies will require a portfolio of techniques for manipulating electron spins in functional nanodevices. Especially, the establishment methods to control spin current is key ingredient essential transfer processing information, enabling faster low-energy operation. However, universal method currents with full-directional controllability tunable magnitude has not been established. Here we show that an artificial material called magnetic...
Resonant soft x-ray emission (SXE) spectra of the mixed valence vanadium oxide ${\mathrm{V}}_{6}{\mathrm{O}}_{13}$ have been recorded for a series excitation energies across V $L$-absorption band. allows one to distinguish between charge neutral low-energy excitations and continuum-excited, more band-like $3d$ band states in spectra. We find that $L$-emission consist two distinct components can be assigned nearly pure states, are strongly hybridized with O $2p$ respectively. Band structure...
Femtosecond reflection spectroscopy was performed on a perovskite-type manganite, Gd0.55Sr0.45MnO3, with the short-range charge and orbital order (CO/OO). Immediately after photoirradiation, large increase of reflectivity detected in mid-infrared region. The optical conductivity spectrum under photoirradiation obtained from Kramers-Kronig analyses changes demonstrates formation metallic state. This suggests that ferromagnetic spin arrangements occur within time resolution (ca. 200 fs)...