DYNAMICALMAGNETIC SUSCEPTIBILITY IN THE SPIN-FERMION MODEL FOR CUPRATE SUPERCONDUCTORS

Val'kov, VV; Dzebisashvili, DM THEORETICAL AND MATHEMATICAL PHYSICS, 193 (3):1853-1864; 10.1134/S004057791712011X DEC 2017

Using the method of diagram techniques for the spin and Fermi operators in the framework of the SU(2)-invariant spin-fermion model of the electron structure of the CuO2plane of copper oxides, we obtain an exact representation of the Matsubara Green’s function D(k, m ) of the subsystem of localized spins. This representation includes the Larkin mass operator ΣL(k, m ) and the strength and polarization operators P(k, m ) and Π(k, m ). The calculation in the one-loop approximation of the mass and strength operators for the Heisenberg spin system in the quantum spin-liquid state allows writing the Green’s function D(k, m ) explicitly and establishing a relation to the result of Shimahara and Takada. An essential point in the developed approach is taking the spin-polaron nature of the Fermi quasiparticles in the spin-fermion model into account in finding the contribution of oxygen holes to the spin response in terms of the polarization operator Π(k, m ).