214 research outputs found
Reply to the comment by C. Capan and K. Behnia on "Nernst effect in poor conductors and in the cuprate superconductors" (cond-mat/0501288)
The comment criticisms (cond-mat/0501288) are completely out of line with the
context of the commented theory (Phys. Rev. Lett. v.93, 217002 (2004)). The
comment neglected essential parts of the theory, which actually addressed all
relevant experimental observations. I argue that the coexistence of the large
Nernst signal and the insulating-like in-plane resistivity in underdoped
cuprates rules out the vortex scenario, but agrees remarkably well with our
theory.Comment: 1 page, 1 figur
Magnetic, thermal and transport properties of Cd doped CeIn
We have investigated the effect of Cd substitution on the archetypal heavy
fermion antiferromagnet CeIn via magnetic susceptibility, specific heat and
resistivity measurements. The suppression of the Neel temperature, T,
with Cd doping is more pronounced than with Sn. Nevertheless, a doping induced
quantum critical point does not appear to be achievable in this system. The
magnetic entropy at and the temperature of the maximum in resistivity are
also systematically suppressed with Cd, while the effective moment and the
Curie-Weiss temperature in the paramagnetic state are not affected. These
results suggest that Cd locally disrupts the AFM order on its neighboring Ce
moments, without affecting the valence of Ce. Moreover, the temperature
dependence of the specific heat below is not consistent with 3D magnons
in pure as well as in Cd-doped CeIn, a point that has been missed in
previous investigations of CeIn and that has bearing on the type of quantum
criticality in this system
Superconductivity without Fe or Ni in the phosphides BaIr2P2 and BaRh2P2
Heat capacity, resistivity, and magnetic susceptibility measurements confirm
bulk superconductivity in single crystals of BaIrP (T=2.1K) and
BaRhP (T = 1.0 K). These compounds form in the ThCrSi (122)
structure so they are isostructural to both the Ni and Fe pnictides but not
isoelectronic to either of them. This illustrates the importance of structure
for the occurrence of superconductivity in the 122 pnictides. Additionally, a
comparison between these and other ternary phosphide superconductors suggests
that the lack of interlayer bonding favors superconductivity. These
stoichiometric and ambient pressure superconductors offer an ideal playground
to investigate the role of structure for the mechanism of superconductivity in
the absence of magnetism.Comment: Published in Phys Rev B: Rapid Communication
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
Wilson ratio in Yb-substituted CeCoIn5
We have investigated the effect of Yb substitution on the Pauli limited,
heavy fermion superconductor, CeCoIn. Yb acts as a non-magnetic divalent
substituent for Ce throughout the entire doping range, equivalent to hole
doping on the rare earth site. We found that the upper critical field in
(Ce,Yb)CoIn is Pauli limited, yet the reduced (H,T) phase diagram is
insensitive to disorder, as expected in the purely orbitally limited case. We
use the Pauli limiting field, the superconducting condensation energy and the
electronic specific heat coefficient to determine the Wilson ratio (),
the ratio of the specific heat coefficient to the Pauli susceptibility in
CeCoIn. The method is applicable to any Pauli limited superconductor in the
clean limit.Comment: 5 pages, 1 table, 4 figure
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
Magnetic, thermodynamic, and electrical transport properties of the noncentrosymmetric B20 germanides MnGe and CoGe
We present magnetization, specific heat, resistivity, and Hall effect
measurements on the cubic B20 phase of MnGe and CoGe and compare to
measurements of isostructural FeGe and electronic structure calculations. In
MnGe, we observe a transition to a magnetic state at K as identified
by a sharp peak in the ac magnetic susceptibility, as well as second phase
transition at lower temperature that becomes apparent only at finite magnetic
field. We discover two phase transitions in the specific heat at temperatures
much below the Curie temperature one of which we associate with changes to the
magnetic structure. A magnetic field reduces the temperature of this transition
which corresponds closely to the sharp peak observed in the ac susceptibility
at fields above 5 kOe. The second of these transitions is not affected by the
application of field and has no signature in the magnetic properties or our
crystal structure parameters. Transport measurements indicate that MnGe is
metal with a negative magnetoresistance similar to that seen in isostructural
FeGe and MnSi. Hall effect measurements reveal a carrier concentration of about
0.5 carriers per formula unit also similar to that found in FeGe and MnSi. CoGe
is shown to be a low carrier density metal with a very small, nearly
temperature independent diamagnetic susceptibility.Comment: 16 pages 23 figure
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