Quasiparticle collapsing in an anisotropic $t$-$J$ ladder

TL;DR

This paper investigates quasiparticle behavior in an anisotropic two-leg $t$-$J$ ladder, revealing a quantum phase transition from a well-defined quasiparticle to a collapsed state involving spin-charge separation, with implications for higher dimensions.

Contribution

It demonstrates a quantum phase transition in a $t$-$J$ ladder where quasiparticles collapse into spin-charge separated entities, extending understanding beyond one dimension.

Findings

Quasiparticle behaves as well-defined in strong rung limit.

Quantum critical point causes quasiparticle collapse.

Phase diagram suggests collapse mechanism in higher dimensions.

Abstract

Quasiparticle collapsing is a central issue in the study of strongly correlated electron systems. In the one-dimensional case, the quasiparticle collapsing in a form of spin-charge separation has been well established, but the problem remains elusive in dimensions higher than one. By using density matrix renormalization group (DMRG) algorithm, we show that in an anisotropic two-leg $t$-$J$ ladder, an injected single hole behaves like a well-defined quasiparticle in the strong rung limit, but undergoes a "phase transition" with the effective mass diverging at a quantum critical point (QCP) towards the isotropic limit. After the transition, the quasiparticle collapses into a composite object of a self-localized charge (holon) and a deconfined spin-1/2 (spinon), accompanied by a substantially enhanced binding energy between two holes. A phase diagram of multi-leg ladders is further obtained, which extrapolates the QCP towards the two-dimensional limit. The underlying novel mechanism generic for any dimensions is also discussed.