Evidence for nodes in the superconducting gap of La2−xSrxCuO4. T2 dependence of electronic specific heat and impurity effects

Superconductivity in two Li-containing compounds of Li2Pd3B and Li2Pt3B was recently discovered. These materials, showing the superconducting transition at 7.2 K and 2.6 K, respectively, have the same cubic structure (P4332) composed of distorted octahedrons without mirror or inversion symmetry along any directions. This is a very interesting feature of those materials in relation to the symmetry of superconductivity. Resistivity measurements in magnetic fields gave their upper critical fields, Hc2(0) = 45 kOe and 19 kOe, respectively. Their specific heat was measured using a heat-pulse relaxation method. The Sommerfeld coefficient (γ) and Debye temperature (θD) terms of Li2Pd3B were given as γ=9.5 mJmol-1K-2 and θD=228 K . The value of C/γT at Tc was calculated to be 1.7. In the same manner, those parameters were described for Li2Pt3B as γ=9.6 mJmol-1K-2, θD=240 K, and C/γTc =0.75, respectively. Since C/γTC in the weakcoupling limit by the BCS theory is 1.43, the value of 1.7 for Li2Pd3B is slightly higher. The electronic specific heat of Li2Pd3B at a zero magnetic field follows the typical exponetial behavior discribed in the BCS theory, while that of Li2Pt3B shows quadratic behavior. This result suggests the line nodes exist in the superconducting gap of Li2Pt3B driven by the spin-orbit interaction.

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Investigation of impurity effects in La2−xSrxCu1−yMyO4 (M=Ga,Zn) by electronic specific heat

Czechoslovak Journal of Physics ◽

10.1007/bf02562731 ◽

1996 ◽

Vol 46 (S3) ◽

pp. 1233-1234 ◽

Cited By ~ 1

Author(s):

N. Momono ◽

T. Nakano ◽

A. Eida ◽

K. Chida ◽

Y. Miura ◽

...

Keyword(s):

Specific Heat ◽

Electronic Specific Heat ◽

Impurity Effects

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MAGNETIC SUSCEPTIBILITY, ELECTRONIC SPECIFIC HEAT AND TRANSPORT PROPERTIES OF SOME INTERMETALLIC COMPOUNDS OF CERIUM

Le Journal de Physique Colloques ◽

10.1051/jphyscol:19711406 ◽

1971 ◽

Vol 32 (C1) ◽

pp. C1-1136-C1-1138 ◽

Cited By ~ 5

Author(s):

J. R. COOPER ◽

C. RIZZUTO ◽

G. OLCESE

Keyword(s):

Magnetic Susceptibility ◽

Specific Heat ◽

Transport Properties ◽

Intermetallic Compounds ◽

Electronic Specific Heat

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PHONON ENHANCEMENT OF THE ELECTRONIC SPECIFIC HEAT NEAR THE MARTENSITIC TRANSFORMATION IN Ti (Ni, Co) CUBIC B2 ALLOYS

Le Journal de Physique Colloques ◽

10.1051/jphyscol:19786457 ◽

1978 ◽

Vol 39 (C6) ◽

pp. C6-1035-C6-1036 ◽

Cited By ~ 1

Author(s):

D. Abbe ◽

R. Caudron ◽

P. Costa

Keyword(s):

Martensitic Transformation ◽

Specific Heat ◽

Electronic Specific Heat

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Specific heat below 3 °K of a gold–zinc and a gold–indium alloy

Canadian Journal of Physics ◽

10.1139/p69-135 ◽

1969 ◽

Vol 47 (10) ◽

pp. 1077-1081 ◽

Cited By ~ 8

Author(s):

Douglas L. Martin

Keyword(s):

Specific Heat ◽

Face Centered Cubic ◽

Electronic Specific Heat ◽

Confidence Limits ◽

Electric Field Gradients ◽

Field Gradients ◽

Atomic Silver ◽

Face Centered ◽

Specific Heat Coefficient ◽

Limiting Value

Face-centered-cubic alloys of gold with 10 atomic % zinc (divalent) and 10 atomic % indium (trivalent), respectively, were measured in the range 0.4 to 3.0 °K. The coefficients of the nuclear specific-heat term were 1.80 ± 0.07 μcal °K/g atom for AuZn and 1.29 ± 0.06 μcal °K/g atom for AuIn (95% confidence limits). For a gold–10 atomic % silver (monovalent) alloy (Martin 1968) the nuclear term was 0.44 μcal °K/g atom. These results show that electric field gradients in alloys are not simply proportional to the valence difference of the components, a conclusion which may be drawn from NMR results. For the AuZn alloy the electronic specific-heat coefficient (γ) is 153.4 ± 0.7 μcal/°K2 g atom and the limiting value of the Debye temperature (θ0c) is 177.0 ± 0.5 °K. For the AuIn alloy γ is 185.9 ± 0.7 μcal/°K2 g atom and θ0c is 159.1 ± 0.3 °K.

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