Theoretical Study Of Angle-resolved Photoemission Spectroscopy Of Correlated Systems

Angle-resolved photoemission spectroscopy (ARPES) is one of the mostpowerful tools to study the electronic structures in solids, even for solids of strongelectron-electron interactions. It has been extensively applied to investigatehigh-temperature superconductivity, colossal magnetic resistance, electronicstructures of the heavy fermion systems, topological insulators and quantum well.ARPES is also an ideal tool to investigate two-dimensional surface systems. Bymeasurements of ARPES, the cohesive energy can be obtained as a function of givenmomentum. The high energy and momentum resolution of Angle-resolvedphotoemission spectroscopy has been remarkably improved these years and bulksensitive observation has also been developed. Now the Angle-resolvedphotoemission spectroscopy can give quite reliable information about electronstructures of solids, and it thus has been applied to investigate many kinds ofmaterials including the Mott insulators.In materials such as high-temperature superconductive materials, the correlationsamong many electrons play an important role in determining the properties of thematerials. Thus the conventional single-electron approximation cannot give aneffective description for these systems and it’s hard to interpret theARPES obtainedfrom experiments. In order to better understand the properties of these materials, themany-body correlation should be investigated by theoretical methods.In this work, the angle-resolved photoemission spectra (ARPES) are calculatedin the Hubbard model by using cluster perturbation method in the spirit of Green’sfunction. We study the spectral properties of Hubbard model at half-filling with acluster size of12and find that the local density of states displays a smooth evolutionrelated to a phase transition from normal conductor to Mott insulator as theelectron-electron coupling increases. We show that a pseudogap develops from themetallic phase to the insulating phase. Meanwhile, evidence of spin-charge separation is also verified in the calculated single particle spectral functions. These presentedresults are expected to be helpful for understanding experimental ARPES.