Hole-doping effects on a frustrated spin ladder

TL;DR

This study explores how hole doping influences the metal-insulator transition and magnetic properties in a frustrated t-J ladder model with a linked-tetrahedra structure, revealing a first-order transition triggered by geometrical frustration.

Contribution

It demonstrates that strong geometrical frustration induces a first-order metal-insulator transition in a t-J ladder model and analyzes the persistence of the spin-gap phase upon doping.

Findings

Strong frustration triggers a first-order transition to metallicity.

The spin-gap phase can persist in the metallic state depending on frustration strength.

The lowest excited state in the metallic phase can be described by two independent quasiparticles.

Abstract

Hole-doping effects are investigated on the {\it t-J} ladder model with the linked-tetrahedra structure. We discuss how a metal-insulator transition occurs upon hole doping with particular emphasis on the effects of geometrical frustration. By computing the electron density and the spin correlation function by the density matrix renormalization group, we show that strong frustration triggers a first-order transition to a metallic phase, when holes are doped into the plaquette-singlet phase. By examining spin excitations in a metallic case in detail, we discuss whether the spin-gap phase persists upon hole doping according to the strength of frustration. It is further shown that the lowest excited state in a spin-gap metallic phase can be described in two independent quasiparticles.