815 research outputs found
Rapid magnetic oscillations and magnetic breakdown in quasi-1D conductors
We review the physics of magnetic quantum oscillations in quasi-one
dimensional conductors with an open Fermi surface, in the presence of modulated
order. We emphasize the difference between situations where a modulation
couples states on the same side of the Fermi surface and a modulation couples
states on opposite sides of the Fermi surface. We also consider cases where
several modulations coexist, which may lead to a complex reorganization of the
Fermi surface. The interplay between nesting effects and magnetic breakdown is
discussed. The experimental situation is reviewed.Comment: 10 pages, 8 figures, Contribution to the memorial issue in honor of
J. Friedel, C. R. Acad. Sci. Pari
Towards a consistent picture for quasi-1D organic superconductors
The electrical resistivity of the quasi-1D organic superconductor (TMTSF)2PF6
was recently measured at low temperature from the critical pressure needed to
suppress the spin-density-wave state up to a pressure where superconductivity
has almost disappeared. This data revealed a direct correlation between the
onset of superconductivity at Tc and the strength of a non-Fermi-liquid linear
term in the normal-state resistivity, going as r(T) = r0 + AT + BT2 at low
temperature, so that A goes to 0 as Tc goes to 0. Here we show that the
contribution of low-frequency antiferromagnetic fluctuations to the
spin-lattice relaxation rate is also correlated with this non-Fermi-liquid term
AT in the resistivity. These correlations suggest that anomalous scattering and
pairing have a common origin, both rooted in the low-frequency
antiferromagnetic fluctuations measured by NMR. A similar situation may also
prevail in the recently-discovered iron-pnictide superconductors.Comment: ISCOM'09 proceedings to be published in Physica
Study of the charge correlation function in one-dimensional Hubbard heterostructures
We study inhomogeneous one-dimensional Hubbard systems using the density
matrix renormalization group method. Different heterostructures are
investigated whose configuration is modeled varying parameters like the on-site
Coulomb potential and introducing local confining potentials. We investigate
their Luttinger liquid properties through the parameter K_rho, which
characterizes the decay of the density-density correlation function at large
distances. Our main goal is the investigation of possible realization of
engineered materials and the ability to manipulate physical properties by
choosing an appropriate spatial and/or chemical modulation.Comment: 6 pages, 7 figure
New possibility of the ground state of quarter-filled one-dimensional strongly correlated electronic system interacting with localized spins
We study numerically the ground state properties of the one-dimensional
quarter-filled strongly correlated electronic system interacting
antiferromagnetically with localized spins. It is shown that the
charge-ordered state is significantly stabilized by the introduction of
relatively small coupling with the localized spins. When the coupling becomes
large the spin and charge degrees of freedom behave quite independently and the
ferromagnetism is realized. Moreover, the coexistence of ferromagnetism with
charge order is seen under strong electronic interaction. Our results suggest
that such charge order can be easily controlled by the magnetic field, which
possibly give rise to the giant negative magnetoresistance, and its relation to
phthalocyanine compounds is discussed.Comment: 5pages, 4figure
Collective Spin-Density-Wave Response Perpendicular to the Chains of the Quasi One-Dimensional Conductor (TMTSF)2PF6
Microwave experiments along all three directions of the spin-density-wave
model compound (TMTSF)PF reveal that the pinned mode resonance is
present along the and axes. The collective transport is
considered to be the fingerprint of the condensate. In contrast to common quasi
one-dimensional models, the density wave also slides in the perpendicular
direction. The collective response is absent along the least
conducting direction.Comment: 3 pages, 4 figure
Diamagnetism of doped two-leg ladders and probing the nature of their commensurate phases
We study the magnetic orbital effect of a doped two-leg ladder in the
presence of a magnetic field component perpendicular to the ladder plane.
Combining both low-energy approach (bosonization) and numerical simulations
(density-matrix renormalization group) on the strong coupling limit (t-J
model), a rich phase diagram is established as a function of hole doping and
magnetic flux. Above a critical flux, the spin gap is destroyed and a Luttinger
liquid phase is stabilized. Above a second critical flux, a reentrance of the
spin gap at high magnetic flux is found. Interestingly, the phase transitions
are associated with a change of sign of the orbital susceptibility. Focusing on
the small magnetic field regime, the spin-gapped superconducting phase is
robust but immediately acquires algebraic transverse (i.e. along rungs) current
correlations which are commensurate with the 4k_F density correlations. In
addition, we have computed the zero-field orbital susceptibility for a large
range of doping and interactions ratio J/t : we found strong anomalies at low
J/t only in the vicinity of the commensurate fillings corresponding to delta =
1/4 and 1/2. Furthermore, the behavior of the orbital susceptibility reveals
that the nature of these insulating phases is different: while for delta = 1/4
a 4k_F charge density wave is confirmed, the delta = 1/2 phase is shown to be a
bond order wave.Comment: 15 pages, 17 figure
SO(4) Theory of Competition between Triplet Superconductivity and Antiferromagnetism in Bechgaard Salts
Motivated by recent experiments with Bechgaard salts, we investigate the
competition between antiferromagnetism and triplet superconductivity in quasi
one-dimensional electron systems. We unify the two orders in an SO(4) symmetric
framework, and demonstrate the existence of such symmetry in one-dimensional
Luttinger liquids. SO(4) symmetry, which strongly constrains the phase diagram,
can explain coexistence regions between antiferromagnetic, superconducting, and
normal phases, as observed in (TMTSF)PF. We predict a sharp neutron
scattering resonance in superconducting samples.Comment: 5 pages, 3 figures; Added discussion of applicability of SO(4)
symmetry for strongly anisotropic Fermi liquids; Added reference
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