Strong correlation induced charge localization in antiferromagnets

Abstract

The fate of a hole injected in an antiferromagnet is an outstanding issue of strongly correlated physics. It provides important insights into doped Mott insulators closely related to high-temperature superconductivity. Here, we report a systematic numerical study of t-J ladder systems based on the density matrix renormalization group. It reveals a surprising result for the single hole's motion in an otherwise well-understood undoped system. Specifically, we find that the common belief of quasiparticle picture is invalidated by the self-localization of the doped hole. In contrast to Anderson localization caused by disorders, the charge localization discovered here is an entirely new phenomenon purely of strong correlation origin. It results from destructive quantum interference of novel signs picked up by the hole, and since the same effect is of a generic feature of doped Mott physics, our findings unveil a new paradigm which may go beyond the single hole doped system.

Charge modulation as fingerprints of phase-string triggered interference

“…(b) The Fourier transformation of the profile exhibits two peaks at Q0 and 2π − Q0, implying that the oscillatory pattern has a period of 2π/Q0. (c) Upon introducing weak impurities the hole density "collapses" into a localized profile pinned at the localization center [19]. (d) The profile shifted with the localization center notwithstanding, the peaks of the Fourier transformation of the profile remain unchanged, implying the invariance of the period of the charge modulation.…”

Quasiparticle collapsing in an anisotropict−Jladder

“…Such a phase string represents a singular phase shift produced by the scattering between the spin background and doped charge 7,[27][28][29] for general dimensions of bipartite lattice. Its destructive quantum interference has been previously found to lead to the localization of the doped hole in the isotropic limit α = 1 of the t-J ladder with the legnumber N y > 1 20 . The phase string is also responsible for the strong binding found in the quasiparticle collapsing regime of the t-J model (cf.…”

“…3 (b), with the disappearance of the term proportional to 1/N 2 x . It implies the self-localization of the doped hole 20 with the effective mass m * c = ∞ at α ≥ α c . On the other hand, the effective mass can be also determined alternatively.…”

“…(1) by introducing a sign prefactor σ = ± such that c † iσ c jσ → σc † iσ c jσ . This is a generalization of the so-called σ·t-J model in the isotropic limit, where the hopping term H t is replaced by 20 :…”

“…In particular, the breakdown of the quasiparticle in a form of spin-charge separation has been conjectured in the study of doped Mott insulators, notably the high-T c cuprates 1-8 . However, no consensus has been reached yet on how a quasiparticle precisely falls into parts in such strongly correlated electron systems.A t-J square ladder as a quasi one-dimensional (1D) doped Mott insulator system has been intensively investigated [9][10][11][12][13][14][15][16][17][18][19][20][21] . Such systems are beyond a purely 1D system due to the presence of closed loops of various sizes, and can be accurately studied by the DMRG numerical method 22 .…”