Effect of phase string on single-hole dynamics in the two-leg Hubbard ladder

Kazuya Shinjo, Shigetoshi Sota, and Takami Tohyama
Phys. Rev. B 103, 035141 – Published 25 January 2021

Abstract

Optical measurements in doped Mott insulators have discovered the emergence of spectral weights at mid-infrared (MIR) upon chemical doping and photodoping. MIR weights may have a relation to string-type excitation of spins, which is induced by a doped hole generating misarranged spins with respect to their sublattice. There are two types of string effects: one is an Sz string that is reparable by quantum spin flips and the other is a phase string irreparable by the spin flips. We investigate the effect of Sz and phase strings on MIR weights. Calculating the optical conductivity of the single-hole Hubbard model in the strong-coupling regime and the tJ model on two-leg ladders by using time-dependent Lanczos and density-matrix renormalization group, we find that phase strings make a crucial effect on the emergence of MIR weights as compared with Sz strings. Our findings indicate that a mutual Chern-Simons gauge field acting between spin and charge degrees of freedom, which is the origin of phase strings, is significant for obtaining MIR weights. Conversely, if we remove this gauge field, no phase is picked up by a doped hole. As a result, a spin polaron accompanied by a local spin distortion emerges and a quasiparticle with a cosinelike energy dispersion is formed in single-particle spectral function. Furthermore, we suggest a Floquet engineering to examine the phase-string effect in cold atoms.

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  • Received 20 November 2020
  • Revised 8 January 2021
  • Accepted 13 January 2021

DOI:https://doi.org/10.1103/PhysRevB.103.035141

©2021 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Kazuya Shinjo1, Shigetoshi Sota2, and Takami Tohyama1

  • 1Department of Applied Physics, Tokyo University of Science, Tokyo 125-8585, Japan
  • 2Computational Materials Science Research Team, RIKEN Center for Computational Science (R-CCS), Kobe, Hyogo 650-0047, Japan

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Issue

Vol. 103, Iss. 3 — 15 January 2021

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