10,507 research outputs found
Theory of strongly phase fluctuating d-wave superconductors and the spin response in underdoped cuprates
General theory of d-wave quasiparticles coupled to phase fluctuations of
superconducting order parameter is discussed. In the charge sector the
superfluid density is found to conform to Uemura scaling, and the charge
renormalization factor to decrease with underdoping. The spin susceptibilty
exhibits four distinct regimes with increasing frequency and scales with the
superconducting Tc, as observed.Comment: LaTex, 3 pages, proceedings of the M2S-HTSC conference in Rio, May
200
Field evolution of the magnetic structures in ErTiO through the critical point
We have measured neutron diffraction patterns in a single crystal sample of
the pyrochlore compound ErTiO in the antiferromagnetic phase
(T=0.3\,K), as a function of the magnetic field, up to 6\,T, applied along the
[110] direction. We determine all the characteristics of the magnetic structure
throughout the quantum critical point at =2\,T. As a main result, all Er
moments align along the field at and their values reach a minimum. Using
a four-sublattice self-consistent calculation, we show that the evolution of
the magnetic structure and the value of the critical field are rather well
reproduced using the same anisotropic exchange tensor as that accounting for
the local paramagnetic susceptibility. In contrast, an isotropic exchange
tensor does not match the moment variations through the critical point. The
model also accounts semi-quantitatively for other experimental data previously
measured, such as the field dependence of the heat capacity, energy of the
dispersionless inelastic modes and transition temperature.Comment: 7 pages; 8 figure
Matrix representation of the time operator
In quantum mechanics the time operator satisfies the commutation
relation , and thus it may be thought of as being canonically
conjugate to the Hamiltonian . The time operator associated with a given
Hamiltonian is not unique because one can replace by , where satisfies the homogeneous condition
. To study this nonuniqueness the matrix elements of
for the harmonic-oscillator Hamiltonian are calculated in the
eigenstate basis. This calculation requires the summation of divergent series,
and the summation is accomplished by using zeta-summation techniques. It is
shown that by including appropriate homogeneous contributions, the matrix
elements of simplify dramatically. However, it is still not clear
whether there is an optimally simple representation of the time operator.Comment: 13 pages, 3 figure
Ultra-Weak Time Operators of Schrodinger Operators
In an abstract framework, a new concept on time operator, ultra-weak time operator, is introduced, which is a concept weaker than that of weak time operator. Theorems on the existence of an ultra-weak time operator are established. As an application of the theorems, it is shown that Schr¨odinger operators HV with potentials V obeying suitable conditions, including the Hamiltonian of the hydrogen atom, have ultra-weak time operators. Moreover, a class of Borel measurable functions f : R ! R such that f(HV ) has an ultra-weak time operator is found
The Experimental plan of the 4m Resonant Sideband Extraction Prototype for The LCGT
The 4m Resonant Sideband Extraction (RSE) interferometer is a planned prototype of the LCGT interferometer. The aim of the experiment is to operate a powerrecycled Broadband RSE interferometer with suspended optics and to achieve diagonalization of length signals of the central part of the interferometer directly through the optical setup. Details of the 4m RSE interferometer control method as well as the design of the experimental setup will be presented
Origin of the tetragonal-to-orthorhombic (nematic) phase transition in FeSe: a combined thermodynamic and NMR study
The nature of the tetragonal-to-orthorhombic structural transition at
K in single crystalline FeSe is studied using shear-modulus,
heat-capacity, magnetization and NMR measurements. The transition is shown to
be accompanied by a large shear-modulus softening, which is practically
identical to that of underdoped Ba(Fe,Co)As, suggesting very similar
strength of the electron-lattice coupling. On the other hand, a
spin-fluctuation contribution to the spin-lattice relaxation rate is only
observed below . This indicates that the structural, or "nematic", phase
transition in FeSe is not driven by magnetic fluctuations
Heavy metal concentrations in a tropical eel Anguilla bicolor bicolor in Peninsular Malaysia, Malaysia
Powerful Actuation of Magnetized Microtool by Focused Magnetic Field on a Disposable Microfluidic Chip
Enhanced binding revisited for a spinless particle in non-relativistic QED
We consider a spinless particle coupled to a quantized Bose field and show
that such a system has a ground state for two classes of short-range potentials
which are alone too weak to have a zero-energy resonance
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