title: Raman spectrum in the pseudogap phase of the underdoped cuprates: effect of phase coherence and the signature of the KT-type superconducting transition.
abstract: The temperature evolution of the Raman spectrum of the underdoped cuprates is studied in the thermal phase fluctuation scenario with an XY-type lattice model for the phase degree of freedom. It is found that the pair breaking Raman peak depends sensitively on the phase coherence of the pairing order parameter. As a result, the integrated Raman intensity in both the B(1g) and the B(2g)  channels exhibits a dramatic drop across the Kosterlitz-Thouless (KT) transition temperature (T(KT)), when vortex-like phase fluctuation is proliferated. This result, which is consistent with experimental observations, provides further support for the thermal phase fluctuation scenario of the pseudogap phase and the KT-type nature of the superconducting transition in underdoped cuprates.
authors: Department of Physics, Renmin University of China, Beijing 100872, People's Republic of China.
authors: Tao
authors: T
authors: Li
authors: Haijun
authors: H
authors: Liao