Unconventional magnetization plateaus in a Shastry-Sutherland spin tube

TL;DR

This study investigates unconventional magnetization plateaus in a quasi-1D Shastry-Sutherland spin tube, revealing new plateau types stabilized by bound triplon states, using advanced numerical and analytical methods.

Contribution

It introduces the discovery of new magnetization plateaus at 1/5 and 3/4 stabilized by bound triplons, extending understanding of frustrated spin systems.

Findings

Plateaus at 1/6, 1/4, 1/3, 3/8, and 1/2 correspond to Wigner crystals of triplons.

New plateaus at 1/5 and 3/4 are stabilized by bound triplon states.

Distinct magnetization profiles suggest specific NMR signatures.

Abstract

Using density matrix renormalization group (DMRG) and perturbative continuous unitary transformations (PCUTs), we study the magnetization process in a magnetic field for all coupling strengths of a quasi-1D version of the 2D Shastry-Sutherland lattice, a frustrated spin tube made of two orthogonal dimer chains. At small inter-dimer coupling, plateaus in the magnetization appear at 1/6, 1/4, 1/3, 3/8, and 1/2. As in 2D, they correspond to a Wigner crystal of triplons. However, close to the boundary of the product singlet phase, plateaus of a new type appear at 1/5 and 3/4. They are stabilized by the localization of {\it bound states} of triplons. Their magnetization profile differs significantly from that of single triplon plateaus and leads to specific NMR signatures. We address the possibility to stabilize such plateaus in further geometries by analyzing small finite clusters using exact diagonalizations and the PCUTs.