Insulator-metal transition and quasi-flat-band of Shastry-Sutherland lattice

TL;DR

This paper studies the insulator-metal transition in the frustrated Shastry-Sutherland lattice using Slave-Boson mean-field theory, revealing a doping-dependent transition from SDW insulator to metal and the robustness of mobile charges.

Contribution

It introduces a self-consistent analysis of the insulator-metal transition on the Shastry-Sutherland lattice considering quasi-flat bands and frustration effects.

Findings

SDW insulating phase at weak doping

Transition to SDW metallic phase at high doping

Robustness of mobile charge number against temperature

Abstract

Insulator-metal transition is investigated self-consistently on the frustrated Shastry-Sutherland lattice in the framework of Slave-Boson mean-field theory. Due to the presence of quasi-flat band structure characteristic, the system displays a spin-density-wave (SDW) insulating phase at the weak doping levels, which is robust against frustration, and it will be transited into an SDW metallic phase at high doping levels. As further increasing the doping, the temperature or the frustration on the diagonal linking bonds, the magnetic order $m$ will be monotonically suppressed, resulting in the appearance of a paramagnetic metallic phase. Although the Fermi surface of the SDW metallic phase may be immersed by temperature, the number of mobile charges is robust against temperature at weak doping levels.