Unconventional properties of high-temperature superconducting cuprates

Abstract

In spite of much interest in various unconventional properties of superconducting cuprates such as the anisotropic superconductivity, the pseudogap state, the competing state in the underdoped region, strange metal in normal state, and anomalies in the optical sum rules etc, its microscopic mechanism still remains unsolved issues. Here these properties are considered using our recently proposed theory emphasizing that the electronic state of superconductors can be described by doping-dependent composite fermions. It is found that the anisotropy of the superconductive gap and the pseudogap are evaluated, the competing states is derived by mixed states model, and that T-linearity of resistivity and the anomaly of optical sum rules in the nearly optimal doping can be derived from considering the interplay between the composite fermion bands. It is also suggested that a crossover separating the strange metal and the normal metal in the overdoped region can be explained by the coupling effect of composite fermions