Anisotropy of Upper Critical Fields for d- and p-Wave Pairing Superconductivity

The high pressure (50 MPa - 2 GPa) – high temperature synthesized MgB2 bulk materials are characterized by nearly theoretical density (1-2% porosity), 80-98% connectivity, extremely high critical current densities (e.g. at 20 K, in 0–1 T jc=1.3–1.0 MA·cm-2 (with 10% SiC) and jc= 0.92 – 0.73 MA·cm-2 (without doping)), large irreversibility fields (Birr(18.4 K) =15 T and Birr (0 K) = 32.5 T) and high upper critical fields (Bc2 (22 K) =15 T and Bc2(0 K) ~ 42.1 T). The transformation of grain boundary pinning to point pinning in MgB2-based materials with increasing manufacturing temperature (from 800 to 1050 oC) under pressures from 0.1 to 2 GPa correlates well with an increase in critical current density in low external magnetic fields caused by the redistribution of boron and the oxygen impurities in the material structure. As the manufacturing temperature increases, the discontinuous oxygen enriched layers transform into distinct Mg-B-O inclusions and the size and amount of inclusions of higher magnesium borides MgBX (X>4) are reduced. The effect of oxygen and boron redistribution can be enhanced by Ti or SiC additions.

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Upper critical fields of single-crystalline and polycrystalline Ca-Sr-Bi-Cu-O compounds

Applied Physics A Solids and Surface ◽

10.1007/bf00618887 ◽

1988 ◽

Vol 47 (2) ◽

pp. 209-211 ◽

Cited By ~ 5

Author(s):

J. N. Li ◽

K. Kadowaki ◽

M. J. V. Menken ◽

Y. K. Huang ◽

K. Bakker ◽

...

Keyword(s):

Critical Fields ◽

Single Crystalline ◽

Upper Critical Fields

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Magnetization studies on superconducting MgB2 – lower and upper critical fields and critical current density

Solid State Communications ◽

10.1016/s0038-1098(01)00149-1 ◽

2001 ◽

Vol 118 (9) ◽

pp. 445-448 ◽

Cited By ~ 25

Author(s):

Amish G. Joshi ◽

C.G.S. Pillai ◽

P. Raj ◽

S.K. Malik

Keyword(s):

Critical Current Density ◽

Critical Current ◽

Current Density ◽

Critical Fields ◽

Upper Critical Fields

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p-wave pairing in metals

Physical Review B ◽

10.1103/physrevb.15.1395 ◽

1977 ◽

Vol 15 (3) ◽

pp. 1395-1398 ◽

Cited By ~ 71

Author(s):

I. F. Foulkes ◽

B. L. Gyorffy

Keyword(s):

P Wave ◽

Wave Pairing

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Temperature dependence of upper critical fields for clean superconductors of the second kind. II

Zeitschrift für Physik A Hadrons and Nuclei ◽

10.1007/bf01392570 ◽

1969 ◽

Vol 222 (4) ◽

pp. 358-362 ◽

Cited By ~ 4

Author(s):

Gerhart Lüders ◽

Klaus-Dieter Usadel

Keyword(s):

Temperature Dependence ◽

Critical Fields ◽

Upper Critical Fields

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Upper critical fields of superconducting Gd and Tm doped LaSn3: Effects of crystalline electric fields

Solid State Communications ◽

10.1016/0038-1098(73)90060-4 ◽

1973 ◽

Vol 13 (1) ◽

pp. 25-29 ◽

Cited By ~ 15

Author(s):

R.P. Guertin ◽

J.E. Crow ◽

A.R. Sweedler ◽

S. Foner

Keyword(s):

Electric Fields ◽

Critical Fields ◽

Upper Critical Fields ◽

Crystalline Electric Fields

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Extent of Fermi-surface reconstruction in the high-temperature superconductor HgBa2CuO4+δ

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1914166117 ◽

2020 ◽

Vol 117 (18) ◽

pp. 9782-9786

Author(s):

Mun K. Chan ◽

Ross D. McDonald ◽

B. J. Ramshaw ◽

Jon B. Betts ◽

Arkady Shekhter ◽

...

Keyword(s):

Fermi Surface ◽

Surface Reconstruction ◽

Field Measurements ◽

Temperature Dependent ◽

Crucial Issue ◽

Critical Fields ◽

Sign Change ◽

Underdoped Cuprates ◽

Upper Critical Fields ◽

Fermi Surface Reconstruction

High magnetic fields have revealed a surprisingly small Fermi surface in underdoped cuprates, possibly resulting from Fermi-surface reconstruction due to an order parameter that breaks translational symmetry of the crystal lattice. A crucial issue concerns the doping extent of such a state and its relationship to the principal pseudogap and superconducting phases. We employ pulsed magnetic-field measurements on the cuprate HgBa2CuO4+δ to identify signatures of Fermi-surface reconstruction from a sign change of the Hall effect and a peak in the temperature-dependent planar resistivity. We trace the termination of Fermi-surface reconstruction to two hole concentrations where the superconducting upper critical fields are found to be enhanced. One of these points is associated with the pseudogap endpoint near optimal doping. These results connect the Fermi-surface reconstruction to both superconductivity and the pseudogap phenomena.

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