ISSN - 10980121, Physical Review B - Condensed Matter and Materials Physics, 2007, vol. 75, p. -
Effective action of the weakly doped t-J model and spin-wave excitations in the spin-glass phase of La2-x Srx Cu O4
We derive the low-energy effective field theory of the extended t-J model in the regime of light doping. The action includes a previously unknown Berry phase term, which is discussed in detail. We use this effective field theory to calculate spin-wave excitations in the disordered spin spiral state of La2-x Srx Cu O4 (the spin-glass phase). We predict an excitation spectrum with two distinct branches: The in-plane mode has the usual linear spin-wave dispersion and the out-of-plane mode shows nontrivial doping dependent features. We also calculate the intensities for inelastic neutron scattering in these modes. © 2007 The American Physical Society.