Unconventional magnetization plateaus in a Shastry-Sutherland spin tube

¹ Institut de Théorie des Phénomènes Physiques, EPF Lausanne - CH-1015 Lausanne, Switzerland
² Lehrstuhl für Theoretische Physik I, Technische Universität Dortmund - D-44221 Dortmund, Germany, EU

^a salvatore.manmana@jila.colorado.edu

Received: 16 March 2011
Accepted: 10 May 2011

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 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.