Phase diagram of ferrimagnetic ladders with bond-alternation

TL;DR

This paper investigates the phase diagram of a 2-leg bond-alternation ferrimagnetic ladder, revealing how spin mixing and bond alternation can induce energy gaps and phase transitions between different gapless phases.

Contribution

It introduces a quantum renormalization group analysis of ferrimagnetic ladders with bond alternation, highlighting the emergence of energy gaps and phase transitions.

Findings

Bond alternation can open an energy gap in ferrimagnetic ladders.

Gapless phases can be equivalent to 1D half-integer antiferromagnets.

A phase transition exists between two gapless phases.

Abstract

We study the phase diagram of a 2-leg bond-alternation spin-(1/2, 1) ladder for two different configurations using a quantum renormalization group approach. Although d-dimensional ferrimagnets show gapless behavior, we will explicitly show that the effect of the spin mixing and the bond-alternation can open the possibility for observing an energy gap. We show that the gapless phases of such systems can be equivalent to the 1-dimensional half-integer antiferroamgnets, besides the gapless ferrimagnetic phases. We therefore propose a phase transition between these two gapless phases that can be seen in the parameter space.