Zero-energy Majorana modes in spin ladders and a possible realization of the Kitaev model
The Abdus Salam International Center for Theoretical Physics - 34100, Trieste, Italy, EU
2 Center of Condensed Matter Physics, ITP, Ilia University - 0162, Tbilisi, Georgia
3 Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory Upton, NY 11973-5000, USA
Accepted: 12 August 2011
We show that in double-chain Mott insulators (ladders), disordered alternating ionic potentials may locally destroy coherence of magnetic excitations and lead to the appearance of spontaneously dimerized islands inside the Haldane spin-liquid phase. We argue that a boundary between the dimerized and Haldane phases of a spin-1/2 ladder supports a localized zero-energy Majorana fermion mode. Based on these findings we suggest a realization of a generalized Kitaev model where Majorana fermions can propagate in more than one dimension.
PACS: 75.10.Pq – Spin chain models / 75.10.Jm – Quantized spin models, including quantum spin frustration
© EPLA, 2011