Confinement-Deconfinement Transition as an Indication of Spin-Liquid-Type Behavior in Na₂IrO₃

Authors

Zhanybek Alpichshev, Massachusetts Institute of Technology
Fahad Mahmood, Massachusetts Institute of Technology
Gang Cao, University of KentuckyFollow
Nuh Gedik, Massachusetts Institute of Technology

Abstract

We use ultrafast optical spectroscopy to observe binding of charged single-particle excitations (SE) in the magnetically frustrated Mott insulator Na₂IrO₃. Above the antiferromagnetic ordering temperature (T_N) the system response is due to both Hubbard excitons (HE) and their constituent unpaired SE. The SE response becomes strongly suppressed immediately below T_N. We argue that this increase in binding energy is due to a unique interplay between the frustrated Kitaev and the weak Heisenberg-type ordering term in the Hamiltonian, mediating an effective interaction between the spin-singlet SE. This interaction grows with distance causing the SE to become trapped in the HE, similar to quark confinement inside hadrons. This binding of charged particles, induced by magnetic ordering, is a result of a confinement-deconfinement transition of spin excitations. This observation provides evidence for spin liquid type behavior which is expected in Na₂IrO₃.

Document Type

Article

Publication Date

1-9-2015

Notes/Citation Information

Published in Physical Review Letters, v. 114, no. 1, article 017203, p. 1-5.

©2015 American Physical Society

The copyright holder has granted permission for posting the article here.

Digital Object Identifier (DOI)

http://dx.doi.org/10.1103/PhysRevLett.114.017203

Funding Information

This work was supported by the Army Research Office Grant No. W911NF-11-1-0331 (data taking and analysis), NSF Career Award No. DMR-0845296 (experimental setup), and the Alfred P. Sloan Foundation (theory and modeling). G. C. was supported by NSF Grants No. DMR-0856234 and No. DMR-1265162 (material growth).

Repository Citation

Alpichshev, Zhanybek; Mahmood, Fahad; Cao, Gang; and Gedik, Nuh, "Confinement-Deconfinement Transition as an Indication of Spin-Liquid-Type Behavior in Na₂IrO₃" (2015). Physics and Astronomy Faculty Publications. 314.
https://uknowledge.uky.edu/physastron_facpub/314