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Thermopower S and resistivity ρ of Y 1 − x R x Co 2 ( R = Er , Ho) compounds have been measured in the temperature range from 1.5 to 300 K under magnetic fields up to 15 T. Strong enhancement of resistivity and fundamental changes in temperature variation of thermopower are observed at low temperatures in the compounds within the composition range where uniform Co 3d magnetization collapses. The magnetic state of Co 3d electrons has a dominant effect on the characteristic behavior of S and ρ in these compounds.

Ce 2 Pd 3 Si 5 is a new Kondo lattice compound that shows antiferromagnetic ordering at 8.4 K. We have performed the resistances measurement of Ce 2 Pd 3 Si 5 under pressure up to 8 GPa in the interval 2.5–300 K. The hydrostatic pressure was generated by employing a cubic anvil cell. The quantum critical point (QCP) exists around 6 GPa for this system, but the superconductivity is not observed. However, the result reveals the Kondo temperature increases after vanishing the magnetic ordering at around QCP due to the Kondo coherence effect under pressure.

Magnetic penetration depths in the mixed state of a heavy-fermion superconductor CeRu{sub 2} have been measured by muon spin rotation. An anomalous increase of the observed penetration depth associated with the hysteresis peak of magnetization strongly suggests a new vortex phase, possibly a generalized Fulde-Ferrel-Larkin-Ovchinnikov state, near the upper critical field. {copyright} {ital 1997} {ital The American Physical Society}

We present data of the elastic properties of the Laves phase compound CeRu2 in the normal and superconducting state obtained from ultrasound measurements. In the temperature range between the superconducting transition temperature of 6.1 K and 300 K we used a deformation potential coupling approach to describe the temperature dependence of the elastic constants. The elastic anomalies in the superconducting state are characterised with the model of thermally assisted flux flow (TAFF). This enables us to construct a detailed superconducting B-T phase diagram including the vortex dynamics and interpret the peak effect region. Especially the ultrasonic measurements exhibit clearly the connection between the normal state and the superconducting properties. They show that structural fluctuations have strong effects on the superconductivity and on the vortex dynamics.

Detailed magnetisation measurements are presented for a cubic Laves phase superconducting single crystal CeRu 2 . These measurements have been performed in the peak effect regime using Quantum Design SQUID Magnetic Property Measurement System (MPMS). To understand the influence of magnetic field inhomogeneity of this set up, on the measured magnetisation, all the data is recorded for different scan lengths. We clearly demonstrate that some of the anomalous magnetisation results reported in literature are artefacts of field inhomogeneity. We also present a model based on Critical State Model to simulate the effect of field inhomogeneity on the measured magnetisation.

We have succeeded in growing a high-quality single crystal of CeRu 2 and dHvA oscillations have been clearly observed both in the normal and mixed states. The dHvA amplitude of a small dHvA frequency is reduced a little in the mixed state compared to that in the normal state, while that of a large dHvA frequency is reduced strongly. The cyclotron mass is found to become a little smaller in the mixed state than that in the normal state, although the cross-sectional area of the Fermi surface is unchanged from the normal state.

We have measured the electrical resistivity, Hall effect and transverse even voltage in the flux-flow state of CeRu2, CeCo2 and Yb3Rh4Sn13. In all the transport properties, we found a clear anomaly related with the peak effect, which was argued in relation to the inhomogenous superconducting phase proposed by Fulde-Ferrell and Larkin-Ovchinnikov. The pinning force and the transverse even voltage depend largely on sample quality. A deviation from the ordinary BCS prediction, suggesting an anisotropy in the superconducting gap, has been found in the specific head of CeCo2/

We have investigated the pressure effects near the phase boundary between the CDW and the pressure-induced reentrant-superconductivity (r-SC) in ZrTe 3 , where, simultaneously with the collapse of the CDW state, appears again the SC. Fluctuations of the CDW and the SC have become stronger as both transitions approach to the phase boundary. We discuss the possible exsitence of a novel state between the CDW and the r-SC phases.

Electrical resistivity measurements of the insulating Ba 1− x K x BiO 3 ( x = 0, 0.15) under high pressure up to 8 GPa have been performed in order to search for the pressure-induced superconductivity, using a cubic-anvil pressure system. A polycrystal of BaBiO 3 has been prepared by the solid-state reaction method. A single crystal of Ba 0.85 K 0.15 BiO 3 has been synthesized by the electrochemical method from molten salts. The electrical resistivity of both compounds slightly decreases with increasing pressure. However, the temperature dependence still remains semiconductive and no superconductivity is observed.

We measured electrical resistivity under magnetic field ( 13.5 T ) and pressure ( 3 GPa ) in Ce 3 Al 11 to study anomalies at 3.2 and 6.3 K in zero field and ambient pressure. Transverse magnetoresistance shows that Ce 3 Al 11 behaves like a standard Kondo material after the two anomalies disappear. With applied pressure, the low-temperature anomaly moves down to lower temperature very rapidly. After the low-temperature anomaly is suppressed, high-temperature anomaly still stands at almost the same temperature (6.3 K). Ce 3 Al 11 behaves like a ferromagnet with Kondo behavior from the stand point of electrical resistivity under pressure.

Magnetic susceptibility, specific heat and electrical resistivity measurements have been carried out on polycrystalline specimens of CeGe1.66, forming in a tetragonal structure, which is derived from CeGe2 by creation of vacancies at the Ge site. A shoulder in susceptibility, a jump in specific heat and an inflection in resisitivity attributable to magnetic ordering are observed at 6.7 K. Furthermore, a rapid increase in susceptibility, another jump in specific heat and a rapid decrease in the resistivity due to the ferromagnetic ordering are observed below (TC=) 5.3 K. The electronic specific heat coefficient γ is estimated to be about mJ/molK2.

We have measured the electrical resistivity of antiferromagnetic Kondo compounds CeNiGe 3 and CeNi 2 Al 5 under pressure. In CeNiGe 3 , Neel temperature T N initially increases with increasing pressure P up to 3 GPa, then decreases rather steeply with further increasing pressure, and becomes zero at a critical pressure P c ≃ 5.5 GPa . The A and ρ 0 values of the resistivity ρ = ρ 0 + AT 2 in the Fermi liquid relation become maximum around P c . Superconductivity is found below 0.48 K in a wide pressure region from 4 to 10 GPa. In CeNi 2 Al 5 , the similar pressure dependence of T N is found, has a maximum at 3.9 GPa, and becomes zero around 6 GPa.

We have measured the resistivity of antiferromagnetic Ce 0.8 La 0.2 (Ru 0.85 Rh 0.15 ) 2 Si 2 along the tetragonal c-axis under various hydrostatic pressures. At P = 0 GPa we observe no gap-type jump in the resistivity at T N as has been observed for Ce(Ru 0.85 Rh 0.15 ) 2 Si 2 at the spin density-wave (SDW) transition temperature, but rather downward bend with decreasing temperature. At P≥0.48 GPa we observe the gap-type jump just below T N . These facts suggest the recovery of the gap opening due to the Fermi-surface nesting by pressure from a conventional localized antiferromagnetic state.

The intermetallic compound, CeCuAs 2 , crystallizing in a HfCuSi 2 -type tetragonal structure, has recently been shown to exhibit a negative temperature ( T ) coefficient of electrical resistivity ...

Symmetrized elastic moduli of high-quality single-crystalline CeRu 2 have been measured between 2 and 300 K by means of an ultrasonic technique. Both transverse moduli ( C 11 - C 12 )/2 and C 44 soften markedly from 300 to ∼20 K without structural transition. In contrast, the bulk modulus C B shows a normal temperature dependence without softening. These results indicate that there exists a marked structural fluctuation corresponding to a pure transverse strain in the normal conducting state of CeRu 2 . Our analysis, taking account of the deformation potential coupling, reveals that a narrow band with relatively high density of states at E F is responsible for the huge lattice softening.

Single crystals of superconducting U 6 Fe were grown by both the zone-melting method and the Czochralski pulling method. The upper critical field H c 2 was determined from the electrical resistivity in applied magnetic fields, and H c 2 is found to be anisotropic; 13.1 T for the field along the [001] direction and 10.4 T for [110]. Anisotropy of H c 2 is well explained by the effective mass model.

Physical properties of an organic conductor, β'-(BEDT-TTF) 2 IBrCl, were characterized under ambient and extremely high pressures. Semiconducting behavior with activation energy, E a =0.11eV, and antiferromagnetic transition with T N =19.5K were uncovered in the present work. In addition, we have found that this salt showed a sign of superconductivity at 8.0GPa in common with the case of the β'-(BEDT-TTF) 2 ICl 2 , which is the highest-T c superconductor among organics.

We have observed the de Haas-van Alphen (dHvA) oscillation in both the normal and superconducting mixed states of CeRu 2 . The dHvA amplitude in the mixed state is extremely reduced for the large cyclotron orbit or the carrier with a large cross-sectional area of the Fermi surface compared to the small one. We have detected three dHvA branches, ranging from 6×10 5 Oe to 2.3×10 7 Oe. The origin of these branches is well explained by the 4 f -itinerant band model.

The magnetic structure of the intermetallic compound EuGa$_4$ was investigated using single-crystal neutron diffraction with the time-of-flight (TOF) Laue technique on the new diffractometer SENJU at MLF of J-PARC. In spite of high neutron absorption of Eu, a vast number of diffraction spots were observed without isotope enrichment. The magnetic reflections were appeared at the positions with the diffraction indices of $h+k+l{\neq}2n$ below 16 K, indicating that the ordering vector is ${\bf q}=(0~0~0)$. Continuous evolution of magnetic reflection intensity below $T_{\rm N}$ follows a squared Brillouin function for $S$=7/2. By adopting a wavelength-dependent absorption collection, the magnetic structure of EuGa$_4$ was revealed that a nearly full magnetic moment of 6.4$~{\mu}_{\rm B}$ of Eu lies within the basal plane of the lattice. The present study reveals a well-localized divalent Eu magnetism in EuGa$_4$ and demonstrates a high ability of SENJU to investigate materials with high neutron absorption., Comment: 5 pages, 5 figures, 2 Tables. submitted to J. Phys. Soc. Jpn

Low temperature a.c.-susceptibility measurements of the intermetallic compound TmCo 2 under various external magnetic fields up to 1.5 T are reported. Two magnetic phase transitions were found at the temperatures 3.4 and 3.8 K. The origins of the transitions are discussed on the basis of quadrupolar as well as magnetic interactions.

We report here the phase diagrams of EuNi2Ge2 and Eu2Ni3Ge5 studied by ac calorimetry under pressure using a diamond anvil cell. We follow the antiferromagnetic transition for EuNi2Ge2 up to 1.5 GPa. The sudden disappearance of magnetic order at around 2 GPa is confirmed, consistent with the probable occurrence of a first-order valence transition near that pressure. The ac calorimetry results on Eu2Ni3Ge5 clearly show two antiferromagnetic transitions, and suggest that magnetic order persists up to higher pressure than previously expected. At high pressure, where heavy-fermion behavior has been reported, the Neel temperature is decreasing, and magnetic order is expected to disappear at an extrapolated pressure of 12–14 GPa. A semi quantitative analysis of the pressure dependence of the specific heat does not show any large changes, but is compatible with a moderate enhancement of γ. The phase diagrams of Yb and Ce heavy fermion systems are compared and discussed with our system.

The electronic structure of the divalent Eu compound EuAl4, which shows a charge density wave transition at TCDW = 140 K, was studied by hard X-ray angle-integrated photoelectron spectroscopy (HAXPES) and soft X-ray angle-resolved photoelectron spectroscopy (ARPES). The valence band and core-level spectra obtained by HAXPES are consistent with the divalent nature of Eu atoms in EuAl4. From the ARPES results, the Fermi surface as well as band structure in the vicinity of the Fermi energy (EF) of EuAl4 are very similar to those of its isostructural divalent Sr compound SrAl4, which has no 4f electrons. This suggests that the Eu atoms are divalent in EuAl4, and the 4f electrons are localized below 1.8 eV with the Eu 4f7 electronic configuration in the ground state. The ARPES spectra measured along the Γ–(Σ)–Z high-symmetry line did not show significant temperature dependences above and below TCDW within the energy resolution of 80–90 meV. Moreover, the Fermi surface mapping along the kz direction showed that...

We succeeded in growing single crystals of the ferromagnets EuPd2 and EuPt2 with the Laves-type cubic structure by the Bridgman method, namely, heating constituting materials in a Mo crucible up to a high temperature of about 1500 °C. The ferromagnetic properties of EuPd2 and EuPt2 with Curie temperatures of 74 and 100 K, respectively, were confirmed from the results of electrical resistivity, specific heat, and magnetization measurements. The ordered moment is 7 μB/Eu, revealing the Eu-divalent ferromagnetism. The present Eu-divalent electronic state is found to be robust against high pressures of up to 8 GPa and is not changed into the Eu-trivalent state. We also carried out de Haas–van Alphen (dHvA) experiments for EuPd2. The detected dHvA branches in EuPd2 are well explained by the relativistic linearized augmented plane wave (RLAPW) energy band calculations for SrPd2, revealing a closed hole Fermi surface and compensated four closed electron Fermi surfaces.

Magnetoresistance, thermopower, Hall resistivity, ac susceptibility and magnetization have been measured for CeRu 2 in the normal and superconducting phases. In the normal state, there is a magnetic anomaly at 50 K, which is presumably due to development of antiferromagnetic order. The H-T superconducting phase diagram obtained from ac susceptibility indicates the possibility of multiple superconducting phases.

We succeeded in growing high-quality single crystals of the pyrite-type cubic compounds CoSe2 and CoS2 using the transport agent CoBr2 and measured the electrical resistivity, specific heat, magnetic susceptibility, magnetization, and de Haas–van Alphen (dHvA) effect. We confirmed that CoSe2 is an exchange-enhanced paramagnet revealing a broad maximum at around 50 K in the temperature dependence of the magnetic susceptibility. The electronic specific heat coefficient is moderately large, γ = 18 mJ/(K2·mol). On the other hand, CoS2 is a ferromagnet with a Curie temperature TC = 122 K and an ordered moment μs = 0.93 μB/Co. The γ of 21 mJ/(K2·mol) of CoS2 is slightly larger than that of CoSe2. A large ordered moment, together with a large γ, is characteristic of CoS2 because CoS2 is a half-metallic spin state in the ferromagnetic state. Correspondingly, we detected a main dHvA branch with a large cyclotron effective mass of 13m0 in the dHvA experiments. The detected dHvA branches in CoS2 and CoSe2 are discus...

EuRh2Si2 is well known to show a valence transition at a pressure of about 1 GPa from a Eu-divalent (antiferromagnetic) state to a nearly Eu-trivalent (paramagnetic) state, which was clarified using polycrystalline samples. We have succeeded in growing single crystals of EuRh2Si2 by the Bridgman method and studied their electronic properties measuring the electrical resistivity under pressure. EuRh2Si2 indicates a first-order valence transition in the pressure range from 1 to 2 GPa, distinguished by a sharp transition and a prominent hysteresis in the temperature dependence of the electrical resistivity. A critical end point in the valence transition is estimated as \(P_{\text{CEP}} \simeq 2.05\) GPa and \(T_{\text{CEP}} \simeq 170\) K. In the pressure range from 2 to 3 GPa, the electrical resistivity is found to exhibit a characteristic behavior for a moderately heavy-fermion compound such as EuIr2Si2. At pressures higher than 3 GPa, the resistivity reveals a normal metallic behavior in a nearly trivalen...

We succeeded in growing single crystals of a superconductor Zr2Co with the tetragonal structure by the Bridgman method and carried out electrical resistivity, magnetic susceptibility, magnetization, specific heat, and de Haas–van Alphen (dHvA) experiments. Superconductivity is a characteristic revealing that the electronic specific heat at 1.45 K in the form of Ce/T in the superconducting state increases not linearly but as a function of \(\sqrt{H} \) up to a magnetic field close to the upper critical field Hc2 = 11 kOe. The superconducting transition temperature Tsc is found to increase markedly with increasing pressure from Tsc = 5.2 K at ambient pressure to 9.5 K at 8 GPa. From the dHvA experiment, several kinds of dHvA branches are detected, which are well explained by the results of the energy band calculation. The main conduction electrons are Zr-4d and Co-3d electrons.

We have measured the electrical resistivity under pressure for the orthorhombic ferromagnet URhGe2. Its two ferromagnetic ordering temperatures TC2 = 30 K and TC1 = 25 K exhibit different pressure dependences. TC2 increases under pressure from 30 K at ambient pressure to 40 K at 6–8 GPa, while TC1 decreases with increasing pressure and seems to vanish at around 8 GPa. URhGe2 is found to be ferromagnetic even at 8 GPa, and the values of A and ρ0 in the electrical resistivity expression ρ = ρ0 + AT2 are unchanged against pressure.

Resistivity measurement on single-crystalline Ce(Ru0.85Rh0.15)2Si2 sample which shows a spin-density-wave (SDW) transition at a Neel temperature T N =5.5 K has been performed under hydrostatic pressure. A hump-type jump in resistivity due to the SDW transition shifts to lower temperature with increasing pressure, and finally disappears above P=0.5 GPa . The ratio of gapped part of the Fermi-surface along the c-axis is estimated as ∼0.45 for P=0 GPa and almost pressure independent.

Thermopower S and electrical resistivity ρ of cubic Laves phase pseudo-binary compounds Y1−xErxCo2 were measured from 2 to 300 K in magnetic fields up to 15 T . S and ρ show a strong field dependence in a vicinity of the magnetic ordering temperature. The reduction of the exchange magnetic field Bexc acting on Co 3d electrons by Y substitution for Er results in a separation of magnetic transition temperatures of Er and Co subsystems in Y0.4Er0.6Co2. The collapse of the itinerant Co 3d moments of Y0.4Er0.6Co2 is induced by applying external magnetic field about 10 T .

We succeeded in growing a single crystal of the Eu-divalent compound EuAl4 with the BaAl4-type tetragonal structure by the Al self-flux method and measured the electrical resistivity, magnetic susceptibility, magnetization, specific heat, and thermoelectric power. EuAl4 orders antiferromagnetically below TN1 = 15.4 K, with three successive antiferromagnetic transitions at TN2 = 13.2 K, TN3 = 12.2 K, and TN4 = 10.0 K. The latter two transitions are of the first-order. The corresponding magnetization curve indicates three successive metamagnetic transitions with hystereses and saturates above 16 kOe. We observed a plausible characteristic feature of the charge density wave (CDW) below TCDW = 140 K. We also studied an effect of pressure on the electronic state by measuring the electrical resistivity and thermoelectric power. TCDW is found to decrease with increasing pressure at a rate of dTCDW/dP = −54.7 K/GPa and becomes zero at about 2.5 GPa. The present antiferromagnetic ordering is, however, found to be ...

Bi-6p electrons are well known to possess a strong spin–orbit interaction, but a mass correction based on the relativistic effect is scarcely discussed in the electronic state. To clarify the relativistic properties of Bi-6p electrons, we grew single crystals of SrBi3 with the AuCu3-type cubic structure by the Bi self-flux method and carried out electrical resistivity, specific heat, and de Haas–van Alphen (dHvA) experiments. Several kinds of closed Fermi surfaces are observed from the dHvA effect. Among them, three kinds of main Fermi surfaces are compared with the results of full-potential linearized augmented plane wave (FLAPW) energy band calculations under two considerations. One corresponds to the mass correction in the spin–orbit interaction for Bi-6p electrons. The other is without the mass correction. Detected two kinds of the main Fermi surfaces are well explained with and without the mass correction, but a remaining Fermi surface is explained only with the mass correction. The relativistic effe...

We succeeded in growing a single crystal of Ce(2)Coln(8) by the flux method. The results of specific heat and electrical resistivity measurements indicate that Ce(2)Coln(8) is a heavy-fermion superconductor below 0.4 K with an electronic specific heat coefficient gamma as large as 500 mJ/K(2)mol-Ce.

Thermopower S and resistivity ρ of cubic Laves phase compound ErCo2 were measured from 2 to 300 K in magnetic fields up to H=15 T. ErCo2 shows a first-order magnetic transition from paramagnetic to ferrimagnetic state at Curie temperature Tc≈32 K, where the sharp jump in S(T) curve was observed with increasing temperature. Tc increases with increasing H. The magnitude of the jump of S(T) at the first-order magnetic transition increases with increasing H in magnetic field up to 3 T. At higher fields, S(T) curve shows a double transition due to separation Er and Co ordering.

Magnetization curves [MC] and temperature dependence of the AC susceptibility [TS] were measured in the superconducting phase of CeRu 2 with T c =6.55 K in zero field. For fields higher than 0.8 T in [TS], the superconducting susceptibility behaves normally up to the lowest transition temperature T cL where it decreases suddenly; the field-induced reentrant superconductivity occurs at T cL and breaks very sharply to the normal state at T cH (the highest transition temperature). In [MC], an anomaly appears when the magnetization reaches to the extrapolated magnetization of the normal state at H R (reentrant field). Magnetization drops suddenly to negative in the field-increasing process for temperatures below 3.9 K, and it only increases for temperatures above 4.0 K. Reentrant superconductivity occurs between, H R and H c2 . The reentrant phase has positive magnetization in the background.

The temperature and the magnetic field dependencies of magnetoresistivity of paramagnetic RCo 2 compounds (R=Y, Lu, and Sc), and paramagnetic and weakly ferromagnetic Y(Al x Co 1− x ) 2 alloys (0⩽ x ⩽0.15) have been measured at temperatures of 2–300 K, in magnetic fields up to 15 T. The magnetoresistivity is positive in paramagnetic and in weakly ferromagnetic compounds at low temperatures. A simple phenomenological model is proposed to explain the results.

Thermopower (S), resistivity (ρ), and AC susceptibility of Y 1 xGdxCo2 alloys (0 ≤ x ≤ 1) have been measured at temperatures of 2K-300 K in magnetic field from 0 to 15 T. There are 4 composition regions on the phase diagram of Y 1 x Gd x Co 2 : Kondo-type behavior is observed at 0 < x ≤0.05, magnetic cluster glass state is found for x from about 0.07 to 0.12. At higher Gd content, x≥0.13 the ground state of the 4f localized moment subsystem is ferromagnetic. The magnetoresistivity (Δρ) shows unusual large positive values in the magnetically ordered phase 0.15 < x ≤0.3.

Scanning tunneling microscopy and scanning tunneling spectroscopy measurements have been performed on a single crystal of CeRu2 down to 2.2 K under a magnetic field up to 2.0 T. The sample surfaces for the measurements are prepared by cutting or cracking the single crystal at 4.2 K. The vortex lattice has been imaged by mapping the quasiparticle density of states at the Fermi energy on the surface. We have observed that the surface has been covered with microstructures a few nm in diameter. These microstructures are characteristic of the surface when the sample is cut or cracked at low temperature.

The pressure dependence of resistivity for the checkerboard-type charge-ordered (CO) molecular conductor $\ensuremath{\beta}\text{\ensuremath{-}}{(meso\text{-DMBEDT-TTF})}_{2}{\text{PF}}_{6}$ has been investigated. Under the low pressure of 0.6 kbar, the temperature of resistivity minimum $({T}_{\text{min}})$ falls from 90 K at an ambient pressure to 67 K, and after the resistivity has been increased, the superconducting (SC) transition is observed at 4.6 K. By applying magnetic field, the SC state is suppressed and the large positive magnetoresistance (MR) is demonstrated below ${T}_{\text{min}}$ in the CO state. Since the positive MR was observed even in the metallic state under high pressures, the summarized pressure-temperature $(P\ensuremath{-}T)$ phase diagram reveals that the SC state neighbors to the CO-insulating and charge-fluctuated metallic states.

The electrical resistivity and magnetoresistance (MR) of single crystal ${\text{CeAl}}_{2}$ have been measured up to 8 and 3.2 GPa, respectively. The magnetic part of the electrical resistivity ${\ensuremath{\rho}}_{\text{mag}}$ increases as temperature decreases until it shows two maxima around $5\text{ }\text{K}(={T}_{1})$ and $63\text{ }\text{K}(={T}_{2})$ at ambient pressure. As pressure increases, ${T}_{1}$ and ${T}_{2}$ decrease up to 2 and 3 GPa, respectively, but they begin to increase above these pressures. MR changes from negative to positive with increasing pressure. It is suggested that Kondo temperature ${T}_{\mathrm{K}}$ increases as pressure increases. Above 3 GPa, Fermi-liquid behavior obeying ${T}^{2}$ dependence of the electrical resistivity is observed and the coefficient of ${T}^{2}$ dependence diverges around 2.7 GPa. The N\'eel temperature of ${\text{CeAl}}_{2}$ at ambient pressure is $3.8\text{ }\text{K}(={T}_{\mathrm{N}})$ and it is suppressed to zero around 2.7 GPa. In the pressure range of $2.5\text{ }\text{GPa}\ensuremath{\le}P\ensuremath{\le}2.7\text{ }\text{GPa}$, ${\ensuremath{\rho}}_{\text{mag}}(T)$ deviates largely from the normal Fermi-liquid behavior, which suggests the so-called non-Fermi-liquid behavior around 2.7 GPa. Pressure-induced superconductivity was not observed down to 50 mK around 2.7 GPa.

Spin ordering in $\ensuremath{\beta}{\text{-Ag}}_{0.33}{\text{V}}_{2}{\text{O}}_{5}$, a ladder-type pressure-induced superconductor, was observed from NMR and zero-field resonance (ZFR) at ambient pressure as an ordering of a $3{d}^{1}$ electron confined within a molecular orbital formed at two V sites on a rung.

In quasi-two-dimensional $\text{Ce}(\text{Ir},\text{Rh}){\text{In}}_{5}$ system, it has been suggested that the phase diagram contains two distinct domes with different heavy-fermion superconducting states. Here, we report the systematic pressure dependence of the electron transport properties in the normal state of ${\text{CeRh}}_{0.2}{\text{Ir}}_{0.8}{\text{In}}_{5}$ and ${\text{CeIrIn}}_{5}$, which locates in first and second superconducting domes, respectively. We observed non-Fermi liquid behavior at low temperatures in both compounds, including nonquadratic $T$ dependence of the resistivity, large enhancement of the Hall coefficient, and the violation of the Kohler rule in the magnetoresistance. We show that the cotangent of the Hall angle $\text{cot}\text{ }{\ensuremath{\Theta}}_{H}$ varies as ${T}^{2}$, and the magnetoresistance is quite scaled well by the Hall angle as $\ensuremath{\Delta}{\ensuremath{\rho}}_{xx}/{\ensuremath{\rho}}_{xx}\ensuremath{\propto}{\text{tan}}^{2}\text{ }{\ensuremath{\Theta}}_{H}$. The observed transport anomalies are common features of $\text{Ce}M{\text{In}}_{5}$ ($M=\text{Co}$, Rh, and Ir) and high-${T}_{c}$ cuprates, which suggest that the anomalous transport properties observed in ${\text{CeIrIn}}_{5}$ are mainly governed by the antiferromagnetic spin fluctuations not by the Ce-valence fluctuations, which have been proposed to be the possible origin for the second superconducting dome.

We present studies of the thermal, magnetic and electrical transport properties of reduced polycrystalline Pr_2Ba_4Cu_7O_{15-\delta} (Pr247) showing a superconducting transition at Tc = 10 - 16 K and compare them with those of as-sintered non-superconducting Pr247. The electrical resistivity in the normal state exhibited T2 dependence up to approximately 150 K. A clear specific heat anomaly was observed at Tc for Pr247 reduced in a vacuum for 24 hrs, proving the bulk nature of the superconducting state. By the reduction treatment, the magnetic ordering temperature TN of Pr moments decreased from 16 to 11 K, and the entropy associated with the ordering increased, while the effective paramagnetic moments obtained from the DC magnetic susceptibility varied from 2.72 to 3.13 mB. The sign of Hall coefficient changed from positive to negative with decreasing temperature in the normal state of a superconducting Pr247, while that of as-sintered one was positive down to 5 K. The electrical resistivity under high magnetic fields was found to exhibit T^a dependence (a = 0.08 - 0.4) at low temperatures. A possibility of superconductivity in the so-called CuO double chains is discussed., Comment: Science and Technology of Advanced Materials (in press)

A fiber-optic measurement technique is developed for estimating the pressure inside a piston cylinder cell up to approximately 4 GPa, based on the pressure-induced R1 fluorescence line shift of ruby (ruby scale). Ruby scale and a conventional technique (calibration on phase transitions of bismuth) were simultaneously applied to the cell filled with a pressure transmitting medium of isopropyl alcohol. The pressure readings of the two methods were consistent with each other, and no pressure gradient was observed. The ruby scale has the advantages of real time estimation and easy installation in a small space. Because of these advantages, three fibers were simultaneously introduced in the sample space at the same time, and pressure distribution was measured for Fluorinert (FC70:FC77=1:1), Daphne oil 7373, and Fomblin oil (YHVAC 13014).

We report the first observation of a large pressure-induced enhancement of giant magnetoresistance (GMR) in magnetic multilayers (MML). In Fe/Cr MMLs with the Cr layer thickness of approximately 30 A, a crossover from biquadratic to bilinear interlayer exchange coupling (IEC) was observed by applying pressure, and simultaneously the GMR under high pressure (>2 GPa) was enhanced to be twice as large as that at ambient pressure. The enhanced GMR is attributed to the suppression of the biquadratic IEC by applying pressure, and the electrical resistivity in parallel alignment of magnetization also showed a crossover behavior, suggesting an electronic origin for the observed pressure effects.

The competition between magnetic ordering and the Kondo effect in Ce2RhSi3, ordering antiferromagnetically at 7 K, is investigated by the measurements of magnetization, heat capacity and electrical resistivity on the solid solutions, Ce(2-x)La(x)RhSi3, Ce(2-y)Y(y)RhSi3, and Ce2RhSi(3-z)Ge(z), as well as by high pressure studies on this compound. The trends in the Kondo and Neel temperature variations among these alloys are compared to infer the roles of unit-cell volume and electronic structure changes. On the basis of the results, we infer that this compound lies at the peak of Doniach-magnetic-phase-diagram. The high pressure electrical resistivity data indicate that the quantum critical point for this compound is in the vicinity of 4 GPa.