5,815 research outputs found
Investigation of the kinetics of crystallization of molten binary and ternary oxide systems Quarterly status report, 1 Dec. 1967 - 29 Feb. 1968
Reaction kinetics of crystallized molten binary and ternary oxide glass making composition
Transport and the Order Parameter of Superconducting UPt3
We calculate the ultrasonic absorption and the thermal conductivity in the
superconducting state of UPt as functions of temperature and direction of
propagation and polarization. Two leading candidates for the superconducting
order parameter are considered: the and representations. Both
can fit the data except for the ultrasonic absorption in the phase. To do
that, it is necessary to suppose that the system has only a single domain, and
that must be chosen as the most favorable one. However, the theory
requires fine-tuning of parameters to fit the low temperature thermal
conductivity. Thus, transport data favor the theory. Measurements of
the thermal conductivity as a function of pressure at low temperature could
help to further distinguish the two theories.Comment: 7 pages, 4 figure
Local gating of a graphene Hall bar by graphene side gates
We have investigated the magnetotransport properties of a single-layer
graphene Hall bar with additional graphene side gates. The side gating in the
absence of a magnetic field can be modeled by considering two parallel
conducting channels within the Hall bar. This results in an average penetration
depth of the side gate created field of approx. 90 nm. The side gates are also
effective in the quantum Hall regime, and allow to modify the longitudinal and
Hall resistances
Identification of the Orbital Pairing Symmetry in UPt_3
This paper summarizes the results of a comprehensive analysis of the
thermodynamic and transport data for the superconducting phases of UPt_3.
Calculations of the transverse sound attenuation as a function of temperature,
frequency, polarization, and disorder are presented for the leading models of
the superconducting order parameter. Measurements of the specific heat, thermal
conductivity, and transverse sound attenuation place strong constraints on the
orbital symmetry of the superconducting order parameter. We show that the
superconducting A and B phases are in excellent agreement with pairing states
belonging to the odd-parity E_{2u} orbital representation.Comment: 11 pages with 7 figure
Thermal conductivity in B- and C- phase of UPt_3
Although the superconductivity in UPt_3 is one of the most well studied,
there are still lingering questions about the nodal directions in the B and C
phase in the presence of a magnetic field. Limiting ourselves to the low
temperature regime (T<<Delta(0)), we study the magnetothermal conductivity with
in semiclassical approximation using Volovik's approach. The angular dependence
of the magnetothermal conductivity for an arbitrary field direction should
clarify the nodal structure in UPt_3.Comment: 4 pages, 5 figure
Identifying the pairing symmetry in the Sr2RuO4 superconductor
We have analyzed heat capacity and thermal conductivity measurements of
Sr2RuO4 in the normal and superconducting state and come to the conclusion that
an order parameter with nodal lines on the Fermi surface is required to account
for the observed low-temperature behavior. A gapped order parameter is
inconsistent with the reported thermodynamic and transport data. Guided by a
strongly peaked dynamical susceptibility along the diagonals of the Brillouin
zone in neutron scattering data, we suggest a spin-fluctuation mechanism that
would favor the pairing state with the gap maxima along the zone diagonals
(such as for a d_{xy} gap). The most plausible candidates are an odd parity,
spin-triplet, f-wave pairing state, or an even parity, spin-singlet, d-wave
state. Based on our analysis of possible pairing functions we propose
measurements of the ultrasound attenuation and thermal conductivity in the
magnetic field to further constrain the list of possible pairing states.Comment: 7 pages, 5 figures; updated list of references and extended
introduction; to appear in Phys. Rev. B (Oct. 2000
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