15 research outputs found
Pressure Effect on the Antiferromagnetic Compound Ce2Ni3Ge5
In this study, the electrical resistivity and magnetization of a single crystal of Ce2Ni3Ge5 heavy fermion compound were performed under pressure. The resistivity and magnetization showed two antiferromagnetic transitions at ambient pressure. On applying pressure, the transitions merged at 1 GPa. At higher pressures, the antiferromagnetic transition temperature decreases, and disappears. It is suggesting that the critical pressure of Ce2Ni3Ge5 was 4.1 GPa
Pressure-induced structural phase transition and new superconducting phase in UTe2
We report on the crystal structure and electronic properties of the heavy
fermion superconductor UTe2 at high pressure up to 11 GPa, as investigated by
X-ray diffraction and electrical resistivity experiments. The X-ray diffraction
measurements under high pressure using a synchrotron light source reveal
anisotropic linear compressibility of the unit cell up to 3.5 GPa, while a
pressure-induced structural phase transition is observed above 3.5-4GPa at room
temperature, where the body-centered orthorhombic crystal structure with the
space group Immm changes into a body-centered tetragonal structure with the
space group I4/mmm. The molar volume drops abruptly at the critical pressure,
while the distance between the first-nearest neighbor of U atoms increases,
implying a switch from the heavy electronic states to the weakly correlated
electronic states. Surprisingly, a new superconducting phase at pressures
higher than 7 GPa was detected at Tsc above 2K with a relatively low
upper-critical field, Hc2(0). The resistivity above 3.5GPa, thus, in the
high-pressure tetragonal phase, shows a large drop below 230 K, which may also
be related to a considerable change from the heavy electronic states to the
weakly correlated electronic states.Comment: 11 pages, 9 figure
Quantum Criticality in YbCu4Ni
We report on the quantum criticality of YbCuNi as revealed by our
combined micro- and macro-measurements. We determine the crystal structure of
YbCuNi with site mixing by neutron diffraction measurements, which suggests
the possible presence of Kondo disorder. However, decreasing the local spin
susceptibility distribution and the development of spin fluctuations below 10 K
at ambient pressure by muon spin rotation and relaxation measurements suggests
that YbCu4Ni exhibits quantum criticality. Therefore, our experimental results
indicate that YbCu4Ni is a new material that exhibits quantum criticality under
a zero magnetic field and ambient pressure.Comment: 8 pages, 5 figure
Pressure-induced unconventional quantum phase transition with fractionalization in the coupled ladder antiferromagnet C9H18N2CuBr4
We present a comprehensive study of the effect of hydrostatic pressure on the
magnetic structure and spin dynamics in the spin-1/2 coupled ladder compound
CHNCuBr. The applied pressure is demonstrated as a parameter
to effectively tune the exchange interactions in the spin Hamiltonian without
inducing a structural transition. The single-crystal heat capacity and neutron
diffraction measurements reveal that the Nel ordered state
breaks down at and above a critical pressure 1.0 GPa through a
continuous quantum phase transition. The thorough analysis of the critical
exponents indicates that such transition with a large anomalous exponent
into a quantum-disordered state cannot be described by the classic Landau's
paradigm. Using inelastic neutron scattering and quantum Monte Carlo methods,
the high-pressure regime is proposed as a quantum spin liquid phase in
terms of characteristic fully gapped vison-like and fractionalized excitations
in distinct scattering channels.Comment: 6 pages and 4 figures in the main text. The Supplementary Material is
available upon the reques
Structural Phase Transition and Possible Valence Instability of Ce Electron Induced by Pressure in CeCoSi
X-ray powder diffraction and electrical resistivity measurements were
performed on the tetragonal compound CeCoSi under pressure to elucidate the
phase boundary of the pressure-induced structural transition and the change in
the 4 electronic state. The temperature-pressure phase diagram has been
determined from the shift of the Bragg peaks and from the anomaly in the
resistivity. The critical pressure, 4.9 GPa at 300 K,
decreases to 3.6 GPa at 10 K. The decrease of is
due not only to the decrease in volume of the unit cell but also to an
anisotropic shrinkage by cooling. When crossing the boundary to the
high-pressure phase, the resistivity shows a significant drop to exhibit a
metallic temperature dependence. The results of this study strongly suggest
that the structural phase transition can be ascribed to valence instability of
Ce- electron.Comment: 7 pages, 5 figures, submitted to J. Phys. Soc. Jp
Magnetic and transport properties of single crystalline RCoxSn2 (R = Ce and La)
In this study, single crystals of CeCo0.39Sn2 and LaCo0.43Sn2 were grown by the Czochralski pulling method for the first time. These compounds crystallize to the orthorhombic CeNiSi2 type structure with the space group Cmcm. The inverse magnetic susceptibility χ−1 of CeCo0.39Sn2 obeys a Curie-Weiss law above 100 K. The effective magnetic moment is close to the value expected for the Ce3+ ion, indicating that the Ce 4f electrons in CeCo0.39Sn2 are well localized. No magnetic transition is observed down to 2 K. However, the specific heat exhibits an upturn upon cooling below 8 K, suggesting that a magnetic order would occur below 2 K