Showing papers by "Tatsuo C. Kobayashi published in 2001"
TL;DR: In this paper, the pressure dependence of transport properties in CeRhIn5 was studied up to 8.5 GPa by using a diamond-anvil cell, where the superconducting temperature TC has a double-maximum structure with a minimum at 5.2 GPa.
Abstract: The pressure dependence of transport properties in CeRhIn5 was studied up to 8.5 GPa by using a diamond-anvil cell. The electrical resistivity does not follow the T 2 -dependecne of a Fermi liquid nature under any pressure. In this non-Fermi liquid state, superconductivity was observed in a wide pressure range of 1:5 GPa
96 citations
TL;DR: In this article, the authors confirmed bulk-superconductivity of a ferromagnet UGe2 by specific heat measurement, together with the measurements of the electrical resistivity and ac susceptibility, in a pressure range from p = 10 to 15 GPa, where the Curie temperature TC( = 22-36 K) is still high, but another characteristic temperature T* is close to zero.
Abstract: We confirmed bulk-superconductivity of a ferromagnet UGe2 by the specific heat measurement, together with the measurements of the electrical resistivity and ac susceptibility, in a pressure range from p = 10 to 15 GPa, where the Curie temperature TC( = 22-36 K) is still high, but another characteristic temperature T* is close to zero In this pressure range, the heavy fermion state is found to be formed at low temperatures
85 citations
TL;DR: In this paper, the authors compared the de Haas-van Alphen experiment with the results of energy band calculations for rare-earth antiferromagnetic compounds and found that the topology of the Fermi surface is almost unchanged up to 1.0 GPa, but the cyclotron effective mass increases with increasing pressure.
Abstract: That the $4f$ electrons in the rare-earth antiferromagnetic compound ${\mathrm{CeRh}}_{2}{\mathrm{Si}}_{2}$ should be considered as localized electrons at cerium sites has been confirmed by comparing a de Haas--van Alphen experiment to the result of energy band calculations for ${\mathrm{LaRh}}_{2}{\mathrm{Si}}_{2}.$ When pressure p is applied to the compound, the N\'eel temperature ${T}_{\mathrm{N}1}=36 \mathrm{K}$ decreases and finally becomes zero at ${p}_{\mathrm{c}}\ensuremath{\simeq}1.0$--1.1 GPa. The topology of the Fermi surface is found to be almost unchanged up to 1.0 GPa, but the cyclotron effective mass increases with increasing pressure. Above 1.1 GPa, the topology of the Fermi surface changes abruptly. A new Fermi surface is explained by the $4f$-itinerant-band model. The corresponding cyclotron mass is large, being about ${22m}_{0}.$
76 citations
TL;DR: In this paper, the phase diagram of antiferromagnetism and superconductivity in the nuclear spin-lattice relaxation (NSL) measurement was reported and it was shown that the NSL temperature can be reduced to 1.23 with an emergent pseudogap behavior.
Abstract: We report the pressure $(P)$-temperature $(T)$ phase diagram of antiferromagnetism and superconductivity in ${\mathrm{CeRhIn}}_{5}$ and ${\mathrm{CeIn}}_{3}$ revealed by the ${}^{115}\mathrm{In}$ nuclear-spin-lattice-relaxation ${(T}_{1})$ measurement. In the itinerant magnet ${\mathrm{CeRhIn}}_{5},$ we found that the N\'eel temperature ${T}_{N}$ is reduced at $Pg~1.23\mathrm{GPa}$ with an emergent pseudogap behavior. In ${\mathrm{CeIn}}_{3},$ the localized magnetic character is robust against the application of pressure up to $P\ensuremath{\sim}1.9\mathrm{GPa},$ beyond which the system evolves into an itinerant regime in which the resistive superconducting phase emerges. We discuss the relationship between the phase diagram and the magnetic fluctuations.
66 citations
TL;DR: In this article, the magnetic moment is enhanced at a characteristic temperature T * in the ferromagnetic state, where T * is smaller than a Curie temperature T C. This enhancement becomes remarkable in the vicinity of P C * = 1.20 GPa.
Abstract: We performed DC-magnetization and neutron scattering experiments under pressure P for a pressure-induced superconductor UGe 2 . We found that the magnetic moment is enhanced at a characteristic temperature T * in the ferromagnetic state, where T * is smaller than a Curie temperature T C . This enhancement becomes remarkable in the vicinity of P C * =1.20 GPa, where T * becomes 0 K and the superconducting transition temperature T SC shows a maximum. The characteristic temperature T * , which decreases with increasing pressure, also depends on the magnetic field.
55 citations
TL;DR: In this paper, the authors performed DC-magnetization and neutron scattering experiments under pressure ε = 1.20 GPa for a pressure-induced superconductor UGe$_2.
Abstract: We performed the DC-magnetization and neutron scattering experiments under pressure {\it P} for a pressure-induced superconductor UGe$_2$. We found that the magnetic moment is enhanced at a characteristic temperature {\it T}$^{*}$ in the ferromagnetic state, where {\it T}$^{*}$ is smaller than a Curie temperature {\it T}$_{\rm C}$. This enhancement becomes remarkable in the vicinity of {\it P}$_{\rm C}^{*}$ = 1.20 GPa, where {\it T}$^{*}$ becomes 0 K and the superconducting transition temperature {\it T}$_{\rm SC}$ shows a maximum. The characteristic temperature {\it T}$^{*}$, which decreases with increasing pressure, also depends on the magnetic field.
47 citations
20 citations
TL;DR: In this article, it was shown that the 1-ML Sb/Si(100) interface is metastable at a temperature of about 750°C and becomes rough upon brief annealing, although the Sb-dimer-row structure of the top layer is completely preserved.
Abstract: Using scanning tunneling microscopy observations, it has been found that the atomically flat 1-ML Sb/ Si(100) interface is metastable at a temperature of about 750°C and becomes rough upon brief annealing, although the Sb-dimer-row structure of the top layer is completely preserved. The roughening is explained by displacive adsorption of Sb (i.e., by substitution of the top-layer Si atoms by Sb atoms) and this phenomenon is suggested to be a common one for group-V adsorbates on Si(100) and Ge(100) surfaces.
8 citations
TL;DR: In this paper, NdBa 2 Cu 3 O y (Nd123) thin films are deposited on ( 1 0 0 )MgO, Y-stablized ZrO (YSZ), and SrTiO 3 (STO) at the low temperature of 650°C by pulsed laser ablation with a shadow mask.
Abstract: NdBa 2 Cu 3 O y (Nd123) thin films are deposited on ( 1 0 0 )MgO, ( 1 0 0 )Y-stablized ZrO (YSZ) and ( 1 0 0 )SrTiO 3 (STO) at the low temperature of 650°C by pulsed laser ablation with a shadow mask (eclipsed pulsed laser deposition (PLD)). X-ray diffraction and reflection high-energy electron diffraction patterns show that all thin films are oriented in ( 0 0 1 ) direction. Compared with the conventional PLD samples, the eclipsed PLD samples exhibit a narrower superconducting transition width ( ΔT c ). The suppression of ΔT c is believed to result from the elimination of droplets and the stoichiometric deviation of Nd specie. The film on STO shows better superconducting properties than those on YSZ and MgO. Its onset T c , ΔT c and J c reaches 93.5 K, 3.5 K and 6×10 6 A/cm 2 , respectively. A Nd123/MgO thin film step-edge junction is prepared as well. A typical RSJ-like (Josephson) current–voltage curve is observed.
5 citations
TL;DR: The superconducting transition was also confirmed by the appearance of the Meissner effect in the susceptibility of quasiparticles under high pressure in UGe$_2$.
Abstract: Recently co-existence of the ferromagnetism and superconductivity was reported in the high-pressure region (1.0-1.6 GPa) in UGe$_2$. We performed the heat capacity measurement on UGe$_2$ under high pressure. At 1.13 GPa, we found a peak corresponding to the superconducting transition. The superconducting temperature $T_{SC}$ and ${\it\Delta} C/(\gamma T_{SC})$ are 0.6 K and 0.25, respectively. The superconducting transition was also confirmed by the appearance of the Meissner effect in the {\it ac} susceptibility. From these results, we confirm a bulk nature of the superconductivity in UGe$_2$. The value of $C/T$ ($\sim$ 95 mJ/moleK$^2$) just above $T_{SC}$ at 1.15 GPa is as much as 3 times larger than that at ambient pressure, which indicates a large mass enhancement of quasiparticles under high pressure.
5 citations
TL;DR: In this paper, the temperature dependence of the magnetic susceptibility and the high-field magnetization up to 55 T was measured for URu2Si2 under high pressures up to 1 GPa.
Abstract: The temperature dependence of the magnetic susceptibility and the high-field magnetization up to 55 T are measured for URu2Si2 under high pressures up to 1 GPa. Both T χ max and TN in the susceptibility increase with increasing pressure. The value of the susceptibility below T χ max decreases with increasing pressure. The three high-field metamagnetic transitions at Hc1=35.1 T, Hc2=36.5 T and Hc3=39.6 T at ambient pressure, show different pressure-dependent behaviors. The metamagnetic transition at Hc1 broadens but survives and its transition field increases with increasing pressure. However, the transition at Hc2 is smeared out and disappears above 0.4 GPa. The transition at Hc3 broadens more clearly than the transition at Hc1. The fact that both T χ max and the metamagnetic transition fields increase suggests that the interaction between the f-electrons and the conduction electrons is enhanced by pressure.
TL;DR: In this article, the authors investigated field-induced long-range ordering by heat capacity and high-field magnetization measurements in Haldane gap system Ni(C 5 H 14 N 2 ) 2 N 3 (ClO 4 ) (NDMAZ).
Abstract: Field-induced long-range ordering is investigated by heat capacity and high-field magnetization measurements in Haldane gap system Ni(C 5 H 14 N 2 ) 2 N 3 (ClO 4 ) (NDMAZ). In the high-field magnet...
TL;DR: In this article, a Haldane system was studied in the magnetic field up to 10 T in order to investigate the field-induced long-range ordering and the spin excitation.
TL;DR: The appearance of the field-induced long-range ordering was observed directly by a proton NMR measurement in Haldane gap system, Ni(C5H14N2)2N3(PF6) (NDMAP) as mentioned in this paper.
Patent•
16 Mar 2001
TL;DR: In this article, the authors proposed a method to mass-produce a radio wave absorber with excellent waterproofness only by simply fixing radio wave absorbing sticks to a frame body by continuously producing the radioswarp absorbing stick through drawing molding.
Abstract: PROBLEM TO BE SOLVED: To efficiency mass-produce a radio wave absorber with excellent waterproofness only by simply fixing radio wave absorbing sticks to a frame body by continuously producing the radio wave absorbing stick through drawing molding. SOLUTION: A glass fiber bundle as an aligned inorganic fiber bundle 1 is continuously supplied and the glass fiber bundle is impregnated with a vinyl ester resin as a thermosetting resin 2. Besides, as a radio wave absorbing member 3, paper of width 8 mm composed of carbon fiber of a specified resistance is continuously supplied. The glass fiber bundle 1 impregnated with the resin 2 is abutted to a roll, opened and led into a metallic mold 4, and paper is led into the metallic mold 4 (heated to 100 to 150 deg.C) so as to be positioned at the center of the glass fiber bundle 1 and drawn by a suitable drawing means 8 so that a radio wave absorbing stick 5 having a rectangular cross section can be provided. The radio wave absorbing stick 5 is cut at every length of 4 m by a cutting member 9. In this case, a suitable waterproofing means is applied to an end face of the radio wave absorbing stick 5.
TL;DR: In this article, a high-quality single crystal of CeRh2Si2 with a residual resistivity ratio of 110.5% was grown under a pressure of 1.1 GPa, where superconductivity was found below Tc=0.38