Quantum phases of ferromagnetically coupled dimers on Shastry-Sutherland lattice

TL;DR

This paper investigates the quantum phase diagram of ferromagnetically coupled dimers on the Shastry-Sutherland lattice, revealing six distinct phases and analyzing their properties using DMRG, which broadens understanding of magnetic quantum phases.

Contribution

The study is the first to explore the ground state phases of ferromagnetically coupled dimers on SSL using DMRG, identifying six novel quantum phases and their phase boundaries.

Findings

Identified six quantum phases in the model.

Determined phase boundaries using correlation functions and energies.

Found correlation length is typically less than four lattice units.

Abstract

The ground state (gs) of antiferromagnetically coupled dimers on the Shastry-Sutherland lattice (SSL) stabilizes many exotic phases and has been extensively studied. The gs properties of ferromagnetically coupled dimers on SSL are equally important but unexplored. In this model the exchange coupling along the $x$-axis ($J_x$) and $y$-axis ($J_y$) are ferromagnetic and the diagonal exchange coupling ($J$) is antiferromagnetic. In this work we explore the quantum phase diagram of ferromagnetically coupled dimer model numerically using density matrix renormalization group (DMRG) method. We note that in $J_x$-$J_y$ parameter space this model exhibits six interesting phases:(I) stripe $(0,\pi)$, (II) stripe $(\pi,0)$, (III) perfect dimer, (IV) $X$-spiral, (V) $Y$-spiral and (VI) ferromagnetic phase. Phase boundaries of these quantum phases are determined using the correlation functions and gs energies. We also notice the correlation length in this system is less than four lattice units in most of the parameter regimes. The non-collinear behaviour in $X$-spiral and $Y$-spiral phase and the dependence of pitch angles on model parameters are also studied.