Effects of impurities in Spin Bose-Metal phase on a two-leg triangular strip

TL;DR

This paper investigates how nonmagnetic impurities affect the Spin Bose-Metal phase in a two-leg triangular strip, revealing that impurities act as relevant perturbations that create oscillating bond energy and spin susceptibility textures, bridging 1D and 2D spin liquid behaviors.

Contribution

It provides a detailed analysis of impurity effects in the SBM phase, including calculations of local observables and their power-law decay, connecting 1D and 2D spin liquid physics.

Findings

Impurities are relevant perturbations that cut the system into two parts.

Bond energy and spin susceptibility exhibit oscillating textures near impurities.

Textures decay as a power law with distance, with exponents depending on the Luttinger parameter.

Abstract

We study effects of nonmagnetic impurities in a Spin Bose-Metal (SBM) phase discovered in a two-leg triangular strip spin-1/2 model with ring exchanges (D. N. Shenget al, arXiv:0902.4210). This phase is a quasi-1D descendant of a 2D spin liquid with spinon Fermi sea, and the present study aims at interpolating between the 1D and 2D cases. Different types of defects can be treated as local energy perturbations, which we find are always relevant. As a result, a nonmagnetic impurity generically cuts the system into two decoupled parts. We calculate bond energy and local spin susceptibility near the defect, both of which can be measured in experiments. The Spin Bose-Metal has dominant correlations at characteristic incommensurate wavevectors that are revealed near the defect. Thus, the bond energy shows a static texture oscillating as a function of distance from the defect and decaying as a slow power law. The local spin susceptibility also oscillates and actually {\it increases} as a function of distance from the defect, similar to the effect found in the 1D chain [S. Eggert and I. Affleck, Phys. Rev. Lett. {\bf 75}, 934 (1995)]. We calculate the corresponding power law exponents for the textures as a function of one Luttinger parameter of the SBM theory.