Papers by Yoichi Miyahara
Zenodo (CERN European Organization for Nuclear Research), Jul 6, 2023
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Physical Review Letters, 2013
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Hyomen to shinku, Oct 10, 2018
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Meeting abstracts of the Physical Society of Japan, Mar 15, 1999
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Springer proceedings in physics, 2001
ABSTRACT The angle-resolved tunneling spectroscopy has been performed on the conduction band of S... more ABSTRACT The angle-resolved tunneling spectroscopy has been performed on the conduction band of Si. Heavily doped n-Si(111) wafer pairs were bonded to form the SIS tunnnel junctions with various in-plane crystal-axis angles between the two crystals. The angle dependence of tunneling originates from the condition of the conservation of transverse component of momentum, together with the energy conservation, of the tunneling Bloch electrons. Rom the angle dependence of the tunneling characteristics, the conduction band structure of Si was derived along the orbit in the k-space, whose projection on the (111) plane forms a circle centered at k=0 and passes the bottom of the conduction band.
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Japanese Journal of Applied Physics, Apr 1, 1996
Tunneling measurements were carried out to investigate the valence band structure of Pb1-x EuxTe ... more Tunneling measurements were carried out to investigate the valence band structure of Pb1-x EuxTe with x=0.038. A marked decrease in the dI/ dV has been observed in the energy range of Eu-4f states. It was found that the top edge of the Eu-4f states lies 0.13 eV below the top of the valence band for x=0.038.
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Journal of Physics: Condensed Matter, Sep 30, 1996
Tunnelling spectroscopy measurements were carried out on the mixed crystal 0953-8984/8/40/010/img... more Tunnelling spectroscopy measurements were carried out on the mixed crystal 0953-8984/8/40/010/img2 to investigate the change in the density of states in the CDW state. The temperature dependences of the CDW energy gap widths were obtained. Experiments showed that the flattening of the peak in the 0953-8984/8/40/010/img3 curve with increasing x corresponds to the decrease in the CDW energy gap. A
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Surface Science, Jun 1, 1997
ABSTRACT Scanning tunneling microscopy has been used to investigate the effects of hafnium impuri... more ABSTRACT Scanning tunneling microscopy has been used to investigate the effects of hafnium impurities on the charge density wave (CDW) state in 1T-TaS2 at room temperature. The STM images have shown that Hf atom strongly affects the CDW state to destroy its long range order and the CDW state has changed to a characteristic one, which has a parallel-line structure in small regions. It suggests that the CDW state has become a single-q CDW state from a triple-q CDW state in the regions due to the strong pinning by Hf. copyright 1997 Elsevier Science B.V.
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Journal of Physics: Condensed Matter, Mar 27, 1995
The CDW energy gap structure of TiSe2 has been observed by tunnelling spectroscopy and its temper... more The CDW energy gap structure of TiSe2 has been observed by tunnelling spectroscopy and its temperature dependence obtained for 77 K<or=T<or=295 K. In addition to the energy gap associated with the CDW with Tc=201 K, a narrower gap structure was observed to persist at higher temperature, which explains the negative temperature coefficient of the rho -T curve above Tc.
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Journal of Experimental and Theoretical Physics, Dec 1, 2003
Tunneling measurements of dI/dV, d2I/dV2, and d3I/dV3 were formed along the C3 axis (normally to ... more Tunneling measurements of dI/dV, d2I/dV2, and d3I/dV3 were formed along the C3 axis (normally to layers) for Bi2Te3 and Sb2Te3 layered semiconductors in the temperature range 4.229 5 K. Temperature dependences of the forbidden band energy Eg were obtained. The forbidden band energy in Bi2Te3 was 0.20 eV at room temperature and increased to 0.24 eV at T=4.2 K. The Eg value for Sb2Te3 was 0.25 eV at 295 K and 0.26 eV at 4.2 K. The distance between the top of the higher valence band of light holes and the top of the valence band of heavy holes situated lower was found to be ΔEV≈19 meV in Bi2Te3; this distance was independent of temperature. The conduction bands of Bi2Te3 and Sb2Te3 each contain two extrema with distances between them of ΔEc≈25 and 30 meV, respectively.
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Applied Surface Science, Feb 1, 1999
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Applied Surface Science, Mar 1, 2002
A non-contact atomic force microscope (NC-AFM) based on a microfabricated piezoelectric cantileve... more A non-contact atomic force microscope (NC-AFM) based on a microfabricated piezoelectric cantilever is presented. A single piezoelectric lead zirconate titanate thin film layer on the cantilever serves as deflection sensing, cantilever oscillation and feedback actuation. Since such an AFM requires neither external oscillator nor external deflection sensor, considerably simple instrumentation becomes possible even for extreme environments such as low temperature
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Nature Materials
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Journal of the Japanese Association for Infectious Diseases, 1981
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Bulletin of the American Physical Society, 2018
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The Journal of Chemical Physics, 2018
In this work, we explore Franck-Condon blockade in the “redox limit,” where nuclear relaxation pr... more In this work, we explore Franck-Condon blockade in the “redox limit,” where nuclear relaxation processes occur much faster than the rate of electron transfer. To this end, the quantized rate expressions for electron transfer are recast in terms of a quantized redox density of states (DOS) within a single phonon mode model. In the high temperature regime, this single-particle picture formulation of electron transfer is shown to agree well with the semi-classical rate and DOS expressions developed by Gerischer and Hopfield. Upon incorporation into a two electrode formulation, utilizing the master equation approach, the low temperature quantized conductance features of Franck-Condon blockade are reproduced. Moreover, at sufficiently large reorganization energies, it is argued that Franck-Condon blockade should also be observable in room temperature systems. In general, this work aims to further bridge descriptions of electron transfer and transport in the single-particle picture.
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Seebeck coefficients (S) were measured in TiS2-xSex for 0≤×≤2 in the temperature range 77-285 K. ... more Seebeck coefficients (S) were measured in TiS2-xSex for 0≤×≤2 in the temperature range 77-285 K. For TiS2 (x=0), S was negative and its absolute value increased linearly with temperature, attaining to 170∼250μ V/K, depending on individual samples, at room temperature. With increasing x, the absolute value of temperature coefficient (TC) of S decreased in the temperature region T ≥ 170K. At x ≈ 1.5, TC was reduced to zero and changed its sign for larger x. This behavior is explained by the fact that the valence band of this system consists of S 3p and/or Se 4p bands and shifts upward with increasing x. For TiSe2 (x=2), S became positive for T ≥ 270K due to the increase in the effect of valence band with increasing temperature. The charge density wave (CDW) transition at 200K in TiSe2 opens the CDW gap and pushes down the lower edge of CDW gap with decreasing temperature. Below 150K, S is controlled by the upper CDW band consisting of Ti 3d band. Thermoelectric behavior of this system...
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Papers by Yoichi Miyahara