3,033 research outputs found
Quantum critical point and superconducting dome in the pressure phase diagram of o-TaS3
We measure the electrical resistance of o-TaS3 between 1K and 300K under
pressures up to 20GPa. We observe a gradual decrease of the charge density wave
transition temperature with increasing pressure P following a mean-field
quantum fluctuation power law with a quantum critical point at a pressure Pc =
11.5GPa. Around the quantum critical point we observe a superconducting dome
with a maximum superconducting transition temperature Tc = 3.1K. Such dome is
similar to superconducting domes around other types of order suggesting that
the QCP is directly responsible for the enhancement of superconductivity
through a universal mechanism still not well understood.Comment: To be published in PRB as a Rapid Communication. 11 pages with 4
figure
Direct observation of the influence of the As-Fe-As angle on the Tc of superconducting SmFeAsOF
The electrical resistivity, crystalline structure and electronic properties
calculated from the experimentally measured atomic positions of the compound
SmFeAsOF have been studied up to pressures ~20GPa. The
correlation between the pressure dependence of the superconducting transition
temperature (Tc) and crystallographic parameters on the same sample shows
clearly that a regular FeAs tetrahedron maximizes Tc, through
optimization of carrier transfer to the FeAs planes as indicated by the
evolution of the electronic band structures.Comment: 15pages, 4 figure
Applications of PDEs to the study of affine surface geometry
If M=(M,∇) is an affine surface, let Q(M):=ker(H+1m−1ρs) be the space of solutions to the quasi-Einstein equation for the crucial eigenvalue. Let M~=(M,∇~) be another affine structure on M which is strongly projectively flat. We show that Q(M)=Q(M~) if and only if ∇=∇~ and that Q(M) is linearly equivalent to Q(M~) if and only if M is linearly equivalent to M~. We use these observations to classify the flat Type A connections up to linear equivalence, to classify the Type A connections where the Ricci tensor has rank 1 up to linear equivalence, and to study the moduli spaces of Type A connections where the Ricci tensor is non-degenerate up to affine equivalence.Supported by projects ED431F 2017/03, and MTM2016-75897-P (Spain)S
Absence of a structural transition up to 40 Gpa in MgB2 and the relevance of magnesium non-stoichiometry
We report measurements on MgB2 up to ~40GPa. Increasing pressure yields a
monotonous decrease of the lattice parameters and of the c/a ratio, but no
structural transition down to parameters smaller than those of AlB2. The
transition superconducting temperature also decreases with temperature in a
sample dependent way. The results are explained by an increase of the filling
of the 2D pxy bands with pressure, the Mg stoichiometry determining the
starting position of the Fermi level. Our measurements indicate that these hole
bands are the relevant ones for superconductivity.Comment: submitted March 9th 2001, PRB accepte
Correlated pressure effects on structure and superconductivity in LaFeAsO0.9F0.1
We have studied the structural and superconductivity properties of the
compound LaFeAsO0.9F0.1 under pressures up to 32GPa using synchrotron radiation
and diamond anvil cells. We obtain an ambient pressure bulk modulus K_0 =
78(2)GPa, compressibility comparable to some cuprates. At high pressures, the
sample is in the overdoped region, with a linear decrease with pressure
variation of the superconducting transition temperature.Comment: 15 pages, 4 figures, 1 tabl
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