796 research outputs found
Fully gapped superconductivity in Ni-pnictide superconductors BaNi2As2 and SrNi2P2
We have performed low-temperature specific heat and thermal conductivity
measurements on the Ni-pnictide superconductors BaNiAs
(=0.7 K and SrNiP (=1.4 K). The temperature
dependences and of the two compounds are similar to the
results of a number of s-wave superconductors. Furthermore, the concave field
responses of the residual for BaNiAs rules out the presence of
nodes on the Fermi surfaces. We postulate that fully gapped superconductivity
could be universal for Ni-pnictide superconductors. Specific heat data on
BaLaNiAs shows a mild suppression of and
relative to BaNiAs.Comment: 5 pages, 3 figures, to be published in J. Phys.: Conf. Se
Superconductivity in CeCoIn5-xSnx: Veil Over an Ordered State or Novel Quantum Critical Point?
Measurements of specific heat and electrical resistivity in magnetic fields
up to 9 T along [001] and temperatures down to 50 mK of Sn-substituted CeCoIn5
are reported. The maximal -ln(T) divergence of the specific heat at the upper
critical field H_{c2} down to the lowest temperature characteristic of
non-Fermi liquid systems at the quantum critical point (QCP), the universal
scaling of the Sommerfeld coefficient, and agreement of the data with
spin-fluctuation theory, provide strong evidence for quantum criticality at
H_{c2} for all x < 0.12 in CeCoIn5-xSnx. These results indicate the
"accidental" coincidence of the QCP located near H_{c2} in pure CeCoIn5, in
actuality, constitute a novel quantum critical point associated with
unconventional superconductivity.Comment: 12 pages, 4 figure
Non-Fermi Liquid behavior in CeIrIn near a metamagnetic transition
We present specific heat and resistivity study of CeIrIn5 in magnetic fields
up to 17 T and temperature down to 50 mK. Both quantities were measured with
the magnetic field parallel to the c-axis (H || [001]) and within the a-b plane
(H \perp [001]). Non-Fermi-liquid (NFL) behavior develops above 12 T for H ||
[001]. The Fermi liquid state is much more robust for H \perp [001] and is
suppressed only moderately at the highest applied field. Based on the observed
trends and the proximity to a metamagnetic phase transition, which exists at
fields above 25 T for H || [001], we suggest that the observed NFL behavior in
CeIrIn5 is a consequence of a metamagnetic quantum critical point.Comment: 5 pages, 4 figures, submitted to Phys. Rev. Letter
Magnetic Excitations of the 2-D Sm Spin Layers in Sm(La,Sr)CuO4
We present specific heat and susceptibility data on Sm(La,Sr)CuO4 in magnetic
fields up to 9 T and temperatures down to 100 mK. We find a broad peak in
specific heat which is insensitive to magnetic field at a temperature of 1.5 K
with a value of 2.65 J/mol K. The magnetic susceptibility at 5 T continues to
increase down to 2 K, the lowest temperature measured. The data suggest that
the Sm spin system may be an ideal realization of the frustrated Heisenberg
antiferromagnet on the square lattice.Comment: 2 pages, 2 figures, submitted to IC
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