Phase Diagram of the S = 1/2 Frustrated Coupled Ladder System

TL;DR

This paper theoretically explores the magnetic phase diagram of a frustrated S=1/2 coupled ladder system, revealing various magnetic states and phase transitions relevant to recent material realizations.

Contribution

It provides a detailed theoretical analysis of the phase diagram, identifying new gapless and ordered magnetic phases in the frustrated ladder system.

Findings

Existence of nondegenerate spin-gap state in the dimer limit

Presence of infinitely degenerate spin-gap state in weakly-coupled chains

Identification of gapless, magnetically ordered regions with different magnetic orders

Abstract

We present a theoretical study of the magnetic phase diagram of the frustrated coupled ladder structure realized recently in several materials. This system displays a nondegenerate spin-gap state in the dimer limit and an infinitely degenerate spin-gap state in the regime of weakly-coupled zig-zag chains. Between these we demonstrate the existence of gapless, magnetically ordered regions whose order is antiferromagnetic close to the honeycomb lattice limit, and incommensurate along the chains when all three magnetic interactions compete.