Spin-isospin Model of Nav 2 O 5
نویسنده
چکیده
We argue that in the quarter-filled ladder compound NaV2O5 the quasione-dimensional spin system is strongly coupled to a low-energy antiferroelectric mode of the excitonic type. This mode results from the interplay between the electron hopping along the rungs of the vanadium two-leg ladders and the Coulomb repulsion between electrons. The charge ordering observed in sodium vanadate at Tc = 34K corresponds to the softening of the antiferroelectric mode. We consider the spin-isospin model, which describes the spin and low-energy charge degrees of freedom in sodium vanadate. Within this model we explain the observed anomalous temperature-dependence of the dielectric susceptibility at Tc and the midinfrared absorption continuum. We identify the broad structure in the low-energy optical absorption spectrum of NaV2O5 with the continuum formed by two spinons and one low-energy charge excitation. Spin-isospin model of NaV2O5 M. V. Mostovoy, J. Knoester, and D. I. Khomskii Theoretical Physics Institute and Materials Science Center, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
منابع مشابه
حالات مزونها و وابستگی آنها به اسپین و ایزواسپین
Meson is composed of one quark and one antiquark moving under the effect of confinement, oscillating and color potentials. Since quarks are particles with spin , there is a spin-spin interaction potential. Also we have isospins for u and d quarks and we can consider related potentials on isospin-isospin and spin-isospin effects. By comparing the given meson spectrum with the amount calculated...
متن کاملCreation and destruction of a spin gap in weakly coupled quarter-filled ladders.
We investigate weakly coupled quarter-filled ladders with model parameters relevant for NaV(2)O(5) using density-matrix renormalization group calculations on an extended Hubbard model coupled to the lattice. NaV(2)O(5) exhibits super-antiferroelectric charge order with a zigzag pattern on each ladder. We show that this order causes a spin dimerization along the ladder and is accompanied by a sp...
متن کاملJa n 20 01 Charge - ordering phase transition and order - disorder effects in the Raman spectra of NaV
In the ac polarized Raman spectra of NaV 2 O 5 we have found anomalous phonon broadening, and an energy shift of the low-frequency mode as a function of the temperature. These effects are related to the breaking of translational symmetry, caused by electrical disorder that originates from the fluctuating nature of the V 4.5+ valence state of vanadium. The structural correlation length, obtained...
متن کاملElectronic Properties of α ′ - NaV 2 O 5
1 General properties of α −NaV 2 O 5 and motivation for a spectroscopic study Introduction – α −NaV 2 O 5 is one of the several phases in the class of Na x V 2 O 5 systems [1] and until now it is by far the most studied of them. Since 1996 this compound (denoted in the following simply by NaV 2 O 5) has received considerable attention because it was thought to be the second realization, after C...
متن کاملCharge ordering and spin dynamics in NaV(2)O(5).
We report high-resolution neutron inelastic scattering experiments on the spin excitations of NaV(2)O(5). Below T(c), two branches with distinct energy gaps are identified. From the dispersion and intensity of the spin excitation modes, we deduce the precise zigzag charge distribution on the ladder rungs and the corresponding charge order: Delta(c) approximately 0.6. We argue that the spin gaps...
متن کامل