Specific chemical bond relaxation unravelled by analysis of shake-up satellites in the oxygen single site double core hole spectrum of CO2

We recently developed a method dubbed NOTA+CIPSI [A. Ferté, et al., J. Phys. Chem. Lett. 11, 4359 (2020)] to compute single site double core hole (ssDCH or K−2 ) spectra,...

Superconductivity and Magnetic Properties of the t–J Model of Cuprate Perovskites

We apply the spin-wave theory with the additional constraint of zero staggered magnetization to investigate the two-dimensional t–J model in the paramagnetic state in the ranges of hole concentrations 0.02 ≲ x ≲ 0.17 and temperatures T ≲ 100 K. In this region the hole spectrum is nonmetallic and contains a pseudogap with properties similar to those observed in Bi2212 photoemission. The calculated spin correlation length, susceptibility, spin-lattice relaxation times at the Cu and O sites and Cu spin-echo decay time are in qualitative and in some cases in quantitative agreement with experiment in underdoped YBa2Cu3O 6+y. The temperature dependences of these quantities are typical for the quantum disordered regime with a pseudogap in the spectrum of magnetic excitations. In the Eliashberg formalism the hole–magnon interaction was found to be unable alone to give rise to superconductivity. With inclusion of a moderate interaction with apex oxygen vibrations, high-T c 's are obtained for even frequency dx2-y2 pairing.