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Author

N. Miura

Other affiliations: University of Nottingham
Bio: N. Miura is an academic researcher from University of Tokyo. The author has contributed to research in topics: Magnetic field & Cyclotron resonance. The author has an hindex of 30, co-authored 307 publications receiving 4214 citations. Previous affiliations of N. Miura include University of Nottingham.


Papers
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Journal ArticleDOI
TL;DR: In this paper, the magnetic absorption spectra of (CH3NH3)PbI3 were investigated in the Faraday configuration up to 40 T at 4.2 K. The compound consists of three-dimensional networks of corner-sharing octahedra.
Abstract: Magnetoabsorption spectra of (CH3NH3)PbI3 are investigated in the Faraday configuration up to 40 T at 4.2 K. The compound consists of three-dimensional networks of corner-sharing octahedra [PbI6]4−. The Zeeman splitting and the diamagnetic shift are observed, and the effective g-factor and the diamagnetic coefficient are 1.2 ± 0.1 and (2.7 ± 0.1) × 10−6eV/T2, respectively. From the diamagnetic shift, the Bohr radius, the binding energy and the reduced mass of the exciton are estimated to be 28 A, 37 meV and 0.12m0, respectively. The exciton in (CH3NH3)PbI3 is one of typical Wannier-type excitons with large radius, which is in contrast with the exciton in (C10H21NH3)2PbI4, consisting of two-dimensional networks of [PbI6]4−.

404 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the magnetic-field-induced phase transitions of the charge carriers and found that the destruction of the real-space ordering is accompanied with a structural phase transition as well as with the magnetic phase transition and the colossal magnetoresistance effect.
Abstract: We have investigated the magnetic-field-induced phase transitions of ${R}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{MnO}}_{3}$ ($R=\mathrm{Pr}$ and Nd, $x=0.50,$ 0.45 and 0.50, 0.45, 0.40) by measurements of magnetization, magnetoresistance, and magnetostriction utilizing a nondestructive long-pulse magnet (generating up to 40 T). We observed processes where magnetic fields destroy the real-space ordering of the charge carriers and cause insulator-to-metal phase transitions over the whole temperature region below about 250 K. We found that the destruction of the charge ordering is accompanied with a structural phase transition as well as with the magnetic phase transition and the colossal magnetoresistance effect. The different profiles of the temperature vs transition field curve depending on the carrier concentration $x$ may be ascribed to the difference in the entropy between the commensurate and the discommensurate charge-ordered state. It turned out that the stability of the charge-ordered state is strongly correlated with the colinear antiferromagnetic ordering of the localized Mn moments.

267 citations

Journal ArticleDOI
TL;DR: In this paper, the transverse resistance of an intermetallic compound was measured in pulsed high magnetic fields up to 25 T and the giant magnetoresistance was observed due to the field-induced magnetic transition from the antiferromagnetic to the intermediate phase at low temperatures.
Abstract: We have measured the transverse resistance of an intermetallic compound ${\mathrm{Mn}}_{3}\mathrm{GaC}$ in pulsed high magnetic fields up to 25 T. Giant magnetoresistance is observed due to the field-induced magnetic transition from the antiferromagnetic to the intermediate phase at low temperatures. The temperature dependence of magnetoresistance shows a dip at the Curie temperature. The dip can be explained using a simple model of de Gennes and Friedel based on magnetic critical scatterings. The normal Hall coefficient is found to show a striking change at the transition, suggesting that the giant magnetoresistance is caused by the change of the carrier concentration.

235 citations

Journal ArticleDOI
TL;DR: The first observation of doping-induced long-range order in a Haldane-gap system was made in this paper, where a quasi-one-dimensional antiferromagnet was shown to have a magnetically ordered state at low temperatures.
Abstract: Magnetic susceptibility, high-field magnetization, and inelastic neutron scattering experiments are used to study the magnetic properties of a new $S\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1$ quasi-one-dimensional antiferromagnet ${\mathrm{PbNi}}_{2}{\mathrm{V}}_{2}{\mathrm{O}}_{8}$. Interchain interactions are shown to be almost, but not quite, strong enough to destroy the nonmagnetic singlet ground state and the energy gap in the magnetic excitation spectrum. Substituting nonmagnetic ${\mathrm{Mg}}^{2+}$ ( $S\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0$) ions for ${\mathrm{Ni}}^{2+}$ ( $S\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1$) induces a magnetically ordered state at low temperatures. To our knowledge this is the first observation of doping-induced long-range order in a Haldane-gap system.

155 citations

Journal ArticleDOI
01 Apr 1996-Nature
TL;DR: In this article, the authors used tunnel-current spectroscopy to map the quantum-mechanical energy levels of an electron confined in a semiconductor quantum well in a high magnetic field.
Abstract: QUALITATIVE insight into the properties of a quantum-mechanical system can be gained from the study of the relationship between the system's classical newtonian dynamics, and its quantum dynamics as described by the Schrodinger equation. The Bohr–Sommerfeld quantization scheme—which underlies the historically important Bohr model for hydrogen-like atoms—describes the relationship between the classical and quantum-mechanical regimes, but only for systems with stable, periodic or quasi-periodic orbits1. Only recently has progress been made in understanding the quantization of systems that exhibit non-periodic, chaotic motion. The spectra of quantized energy levels for such systems are irregular, and show fluctuations associated with unstable periodic orbits of the corresponding classical system1–3. These orbits appear as 'scars'—concentrations of probability amplitude—in the wavefunction of the system4. Although wavefunction scarring has been the subject of extensive theoretical investigation5–10, it has not hitherto been observed experimentally in a quantum system. Here we use tunnel-current spectroscopy to map the quantum-mechanical energy levels of an electron confined in a semiconductor quantum well in a high magnetic field10–13. We find clear experimental evidence for wavefunction scarring, in full agreement with theoretical predictions10.

120 citations


Cited by
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TL;DR: Spintronics, or spin electronics, involves the study of active control and manipulation of spin degrees of freedom in solid-state systems as discussed by the authors, where the primary focus is on the basic physical principles underlying the generation of carrier spin polarization, spin dynamics, and spin-polarized transport.
Abstract: Spintronics, or spin electronics, involves the study of active control and manipulation of spin degrees of freedom in solid-state systems. This article reviews the current status of this subject, including both recent advances and well-established results. The primary focus is on the basic physical principles underlying the generation of carrier spin polarization, spin dynamics, and spin-polarized transport in semiconductors and metals. Spin transport differs from charge transport in that spin is a nonconserved quantity in solids due to spin-orbit and hyperfine coupling. The authors discuss in detail spin decoherence mechanisms in metals and semiconductors. Various theories of spin injection and spin-polarized transport are applied to hybrid structures relevant to spin-based devices and fundamental studies of materials properties. Experimental work is reviewed with the emphasis on projected applications, in which external electric and magnetic fields and illumination by light will be used to control spin and charge dynamics to create new functionalities not feasible or ineffective with conventional electronics.

9,158 citations

Journal ArticleDOI
18 Oct 2013-Science
TL;DR: In this article, transient absorption and photoluminescence-quenching measurements were performed to determine the electron-hole diffusion lengths, diffusion constants, and lifetimes in mixed halide and triiodide perovskite absorbers.
Abstract: Organic-inorganic perovskites have shown promise as high-performance absorbers in solar cells, first as a coating on a mesoporous metal oxide scaffold and more recently as a solid layer in planar heterojunction architectures. Here, we report transient absorption and photoluminescence-quenching measurements to determine the electron-hole diffusion lengths, diffusion constants, and lifetimes in mixed halide (CH3NH3PbI(3-x)Cl(x)) and triiodide (CH3NH3PbI3) perovskite absorbers. We found that the diffusion lengths are greater than 1 micrometer in the mixed halide perovskite, which is an order of magnitude greater than the absorption depth. In contrast, the triiodide absorber has electron-hole diffusion lengths of ~100 nanometers. These results justify the high efficiency of planar heterojunction perovskite solar cells and identify a critical parameter to optimize for future perovskite absorber development.

8,199 citations

Journal Article
TL;DR: In this paper, transient absorption and photoluminescence-quenching measurements were performed to determine the electron-hole diffusion lengths, diffusion constants, and lifetimes in mixed halide and triiodide perovskite absorbers.
Abstract: Organic-inorganic perovskites have shown promise as high-performance absorbers in solar cells, first as a coating on a mesoporous metal oxide scaffold and more recently as a solid layer in planar heterojunction architectures. Here, we report transient absorption and photoluminescence-quenching measurements to determine the electron-hole diffusion lengths, diffusion constants, and lifetimes in mixed halide (CH3NH3PbI(3-x)Cl(x)) and triiodide (CH3NH3PbI3) perovskite absorbers. We found that the diffusion lengths are greater than 1 micrometer in the mixed halide perovskite, which is an order of magnitude greater than the absorption depth. In contrast, the triiodide absorber has electron-hole diffusion lengths of ~100 nanometers. These results justify the high efficiency of planar heterojunction perovskite solar cells and identify a critical parameter to optimize for future perovskite absorber development.

6,454 citations

Journal ArticleDOI
TL;DR: In this article, the authors present a comprehensive, up-to-date compilation of band parameters for the technologically important III-V zinc blende and wurtzite compound semiconductors.
Abstract: We present a comprehensive, up-to-date compilation of band parameters for the technologically important III–V zinc blende and wurtzite compound semiconductors: GaAs, GaSb, GaP, GaN, AlAs, AlSb, AlP, AlN, InAs, InSb, InP, and InN, along with their ternary and quaternary alloys. Based on a review of the existing literature, complete and consistent parameter sets are given for all materials. Emphasizing the quantities required for band structure calculations, we tabulate the direct and indirect energy gaps, spin-orbit, and crystal-field splittings, alloy bowing parameters, effective masses for electrons, heavy, light, and split-off holes, Luttinger parameters, interband momentum matrix elements, and deformation potentials, including temperature and alloy-composition dependences where available. Heterostructure band offsets are also given, on an absolute scale that allows any material to be aligned relative to any other.

6,349 citations

Journal ArticleDOI
TL;DR: In this article, a review describes the rapid progress that has been made in hybrid organic-inorganic perovskite solar cells and their applications in the photovoltaic sector.
Abstract: Within the space of a few years, hybrid organic–inorganic perovskite solar cells have emerged as one of the most exciting material platforms in the photovoltaic sector. This review describes the rapid progress that has been made in this area.

5,463 citations