Pressure dependence of the magnetization plateaus of SrCu_2(BO_3)_2

TL;DR

This study investigates how pressure affects the magnetization plateaus in SrCu_2(BO_3)_2, revealing that increased pressure lowers critical fields and makes certain plateaus experimentally accessible, supported by an effective classical model.

Contribution

The paper introduces a classical model of interacting pinwheel-shaped spin states to explain the pressure-dependent magnetization plateaus in SrCu_2(BO_3)_2, combining perturbative and graph-based transformations.

Findings

Critical fields decrease with pressure.

Magnetization plateaus shift to lower fields.

Pinwheel crystals are the lowest-energy structures.

Abstract

We show that the critical fields of the magnetization plateaus of the Shastry-Sutherland model decrease significantly upon increasing the ratio of inter- to intra-dimer coupling, and accordingly that the magnetization plateaus of SrCu_2(BO_3)_2 shift to lower field under pressure, making the first two plateaus at 1/8 and 2/15 potentially accessible to neutron scattering experiments. These conclusions are based on the derivation of an effective classical model of interacting pinwheel-shaped spin-2 bound states using a combination of perturbative and graph-based continuous unitary transformations, showing that pinwheel crystals are indeed the lowest-energy plateau structures at low magnetization, and that a simple model of intermediate-range two-body repulsion between pinwheels is able to account quantitatively for the plateau sequence.