A5064993725- Diamond and Carbon-based Materials Research
- High-pressure geophysics and materials
- Atomic and Subatomic Physics Research
- Semiconductor materials and devices
- Metal and Thin Film Mechanics
- Electronic and Structural Properties of Oxides
- Magnetic Field Sensors Techniques
- Mechanical and Optical Resonators
- Advanced MRI Techniques and Applications
- Nonlinear Optical Materials Studies
- Physics of Superconductivity and Magnetism
- Silicon Nanostructures and Photoluminescence
- Advanced Surface Polishing Techniques
- Boron and Carbon Nanomaterials Research
- Advanced Fluorescence Microscopy Techniques
- Force Microscopy Techniques and Applications
- Magneto-Optical Properties and Applications
- Biosensors and Analytical Detection
- Laser-induced spectroscopy and plasma
- Advanced materials and composites
- Photoacoustic and Ultrasonic Imaging
- Advanced Fiber Laser Technologies
- Nanoplatforms for cancer theranostics
- Analytical Chemistry and Sensors
- Catalysis and Oxidation Reactions
National Institute for Materials Science
2021-2024
The University of Tokyo
2016
Magnetocardiography is a contactless imaging modality for electric current propagation in the cardiovascular system. Although conventional sensors provide sufficiently high sensitivity, their spatial resolution limited to centimetre-scale, which inadequate revealing intra-cardiac electrodynamics such as rotational waves associated with ventricular arrhythmias. Here, we demonstrate invasive magnetocardiography of living rats at millimetre-scale using quantum sensor based on nitrogen-vacancy...
We present a sensitive diamond quantum sensor with magnetic field sensitivity of $9.4\ifmmode\pm\else\textpm\fi{}0.1\phantom{\rule{0.2em}{0ex}}\mathrm{pT}/\sqrt{\mathrm{Hz}}$ in near-dc frequency range 5 to 100 Hz. This is based on the continuous-wave optically detected resonance an ensemble nitrogen-vacancy centers along [111] direction (111) single crystal. The long ${T}_{2}^{\ensuremath{\ast}}\ensuremath{\sim}2\phantom{\rule{0.2em}{0ex}}\text{\ensuremath{\mu}}\mathrm{s}$ our and reduced...
Considering the rising popularity of electric vehicles (EVs), it is essential to enhance cruising mileage and extend lifetime batteries. To accomplish this, accurate monitoring charge discharge current battery over a wide temperature range essential. We developed compact diamond quantum sensor head with size 1 × 0.5 cm3, consisting (111) high-pressure high-temperature synthesized nitrogen-vacancy centers, by electron beam irradiation, which was adhered top multimode fiber surrounded...
We investigated spin-echo coherence times T2 of negatively charged nitrogen vacancy center (NV−) ensembles in single-crystalline diamond synthesized by either the high-pressure and high-temperature chemical vapor deposition methods. This study specifically examined magnetic dipole–dipole interaction (DDI) from various electronic spin baths, which are source decoherence. Diamond samples with NV− concentration [NV−] comparable to those neutral substitutional [Ns0] were used for DDI estimation....
We investigated charge states of nitrogen vacancy (NV) centers in diamond single crystals. The were evaluated using concentrations both negatively charged (NV−) and neutral-state (NV0) NV centers. This study specifically examines crystals containing mainly neutral substitutional (N0s), NV− centers, NV0 Results show that the for this depended on (N0s) NVT which is a sum [NV−] [NV0]. fully when ratio [NVT] to [N0s] was 1%–20% our When [NVT]/[N0s] larger than 20%–30%, appeared gradually....
Controllability of nitrogen doping, types nitrogen-related defects, and their charge states in homoepitaxial diamond (001) crystals were investigated. For these purposes, 15N-doped 12C-enriched free-standing chemical vapor deposited grown through long-time growth using methane as the carbon source gas 15N-enriched molecular gas. The formation non-epitaxial crystallites hillocks was suppressed by application oxygen-adding condition. Nitrogen incorporated uniformly into crystals, with a...
We report the density-functional calculations that provide a firm theoretical framework to identify multivacancies and unravel underlying physics in most stable silicon carbide polytype 4H-SiC. The with generalized gradient approximation (GGA) for Si C monovacancy, ${V}_{\mathrm{Si}}$ ${V}_{\mathrm{C}}$, have clarified significantly lower formation energy of vacancy accompanied by efficient pairing relaxation surrounding dangling bonds. Our GGA calculation also predicts next-neighbor...
Abstract A systematic study for the continuous control of nitrogen concentrations in synthetic diamonds ranging from 100 to 0.1 ppm is conducted. Nitrogen grown under high-pressure and high-temperature were controlled at levels by adding Ti/Al Co Fe–Co alloy solvents. In solvents, decreased exponentially 0.2 Ti additions 40 Al additions. The gettering efficiency increased order Co–Al, Co–Ti, Fe–Co–Ti Thus, Co–Ti solvents preferable tuning concentration (>0.2 ppm), whereas promising...
Color centers in wide band-gap semiconductors, which have superior quantum properties even at room temperature and atmospheric pressure, been actively applied to sensing devices. Characterizing the of color semiconductor materials ensuring that these are uniform over a area key issues for developing devices based on centers. In this article, we developed an optics design protocol optimized evaluating used approach develop new microscopy system called columnar excitation fluorescence...
A key challenge in cardiology is the non-invasive imaging of electric current propagation occurring cardiovascular system at an intra-cardiac scale. promising approach for directly mapping dynamics to monitor associated stray magnetic field. However, this field approach, spatial resolution deteriorates significantly as standoff distance between target and sensor increases. Existing sensors usually remain relatively far from provide only centimetre-scale because their operating temperature...
Abstract The reduction of inhomogeneous stress in diamonds is crucially important for extracting excellent performance semiconducting diamonds. In this study, to investigate elastic deformation nitrogen doped (111) diamond films caused by stress, we evaluated the these using confocal Raman microscopy. was detectable when misorientation angle ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>θ</mml:mi> </mml:mrow> <mml:mi...
We employ a dry-type phantom to evaluate the performance of diamond quantum magnetometer with high sensitivity about $6~\mathrm{pT/\sqrt{Hz}}$ from viewpoint practical measurement in biomagnetic sensing. The dry is supposed represent an equivalent current dipole (ECD) generated by brain activity, emulating encephalomagnetic field. spatial resolution evaluated be sufficiently higher than length variation field distribution. minimum detectable ECD moment 0.2 nA m averaging 8000 measurements...
We present a sensitive diamond quantum sensor with magnetic field sensitivity of $9.4 \pm 0.1~\mathrm{pT/\sqrt{Hz}}$ in near-dc frequency range 5 to 100~Hz. This is based on the continuous-wave optically detected resonance an ensemble nitrogen-vacancy centers along [111] direction (111) single crystal. The long $T_{2}^{\ast} \sim 2~\mathrm{\mu s}$ our and reduced intensity noise laser-induced fluorescence result remarkable among sensors. Based Allan deviation analysis, we demonstrate that...
Color centers in wide band-gap semiconductors, which have superior quantum properties even at room temperature and atmospheric pressure, been actively applied to sensing devices. Characterization of the color semiconductor materials ensuring that these are uniform over a area key issues for developing devices based on center. In this article, we will describe principle performance newly developed confocal microscope system with long Rayleigh length (LRCFM). This can characterize wider faster...
Effect of monovacancies on charge states nitrogen vacancy centers in nitrogen-doped diamond single crystal was investigated. Monovacancies were formed by high-energy electron beam irradiation. The concentration ratio negatively charged (NV-) to neutral (NV0) decreased with increase monovacancy. This result attributed the reduction substitutional [Ns0] due capture electrons from Ns0 monovacancies. Fermi energy is located approximately middle bandgap, suggesting that a significant amount are...