Dynamic spin susceptibility of superconducting cuprates: A microscopic theory of the magnetic resonance mode

Abstract

A microscopic theory of the dynamic spin susceptibility (DSS) in the superconducting state within the t-J model is presented. It is based on an exact representation for the DSS obtained by applying the Mori-type projection technique for the relaxation function in terms of Hubbard operators. The static spin susceptibility is evaluated by a sum-rule-conserving generalized mean-field approximation, while the self-energy is calculated in the mode-coupling approximation. The spectrum of spin excitations is studied in the underdoped and optimally doped regions. The DSS reveals a resonance mode (RM) at the antiferromagnetic wave vector Q = π(1,1) at low temperatures due to a strong suppression of the damping of spin excitations. This is explained by an involvement of spin excitations in the decay process besides the particle-hole continuum usually considered in random-phase-type approximations. The spin gap in the spin-excitation spectrum at Q plays a dominant role in limiting the decay in comparison with the superconducting gap which results in the observation of the RM even above $T_c$ in the underdoped region. A good agreement with inelastic neutron-scattering experiments on the RM in YBCO compounds is found.

15 pages, 20 figures, references added

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Cited by in corpus (6)

• Spin fluctuations and high-temperature superconductivity in cuprates
• Dual Features of Magnetic Susceptibility in Superconducting Cuprates: a comparison to inelastic neutron scattering
• Optical and dc conductivities of cuprates: Spin-fluctuation scattering in the t-J model
• Spin excitations and thermodynamics of the antiferromagnetic Heisenberg model on the layered honeycomb lattice
• Electronic spectrum and superconductivity in the extended t-J-V model
• Microscopic theory of high-temperature superconductivity in strongly correlated electronic systems