Influence of a magnetic field on the electronic Raman response in high-Tc cuprates

The effect of a magnetic field parallel to the CuO₂ plane on the Raman spectra is investigated based on the Slave–Boson approach to the t ? t′ ? J model with a Zeeman field and the random-phase approximation. We find that the Raman spectra intensities in the superconducting (SC) state are suppressed for both the B_1g and the B_2g channels with a slight shift of the peaks position toward lower frequency in the B_1g channel and a negligible shift in the B_2g channel due to the Zeeman splitting. There is a field-induced peak and dip structure at low energy response in the B_2g channel at very low temperature. While rising temperature has a similar effect in reducing the Raman response peak in the superconducting (SC) state, it smears out the field-induced peak and dip structure in the B_2g channel. We compare these results with experiments and give explanations based on the field-induced changes of the density of the superconducting condensate, the momentum distribution of the quasiparticle energy and the scattering rate.