Quasi-Spin Correlations in a Frustrated Quantum Spin Ladder

TL;DR

This paper investigates the quasi-spin correlations in a frustrated quantum spin ladder with half magnetization, revealing a phase transition and detailed properties of the magnetization plateau using advanced numerical methods.

Contribution

It introduces a theoretical analysis of quasi-spin correlations in a frustrated spin ladder, linking the findings to experimental observations in BiCu₂PO₆.

Findings

Identification of a gapless-to-gapful phase transition induced by frustration

Observation of a magnetization-plateau state with long-range correlations

Insight into the magnetization curve of BiCu₂PO₆

Abstract

The quasi-spin correlations in a frustrated quantum spin ladder with one-half magnetization are theoretically studied by using the density-matrix renormalization-group method and the quasi-spin transformation. In this model, the frustration induces a gapless-to-gapful phase transition with a strong rung coupling. The gapful state is observed as the one-half magnetization plateau in the magnetization curve. In the magnetization-plateau state, we find that the quasi-spin dimer has a large expectation value with long-ranged correlations. This result does not only comes in useful to clarify the magnetization-plateau state, but gives a crucial information to understand the magnetization curve of the real compound BiCu$_2$PO$_6$, whose effective spin model corresponds to ours.