Non-Fermi liquid correction to uniform spin susceptibility of singlet band below Tc

Abstract

A new expression for the uniform static spin susceptibility below T c in singlet band model has been deduced. The formula takes into account strong electron correlation effects. The comparison of the theoretical curve with experimental data yields another value of 2Δ k BT c than in the case of the usual Fermi liquid. In particular, for YBa 2Cu 3O 7 the extracted ratio 2Δ k BT c = 4.87 and can be interpreted in favor of the superexchange pairing mechanism.