Relevance of the Heisenberg-Kitaev Model for the Honeycomb Lattice Iridates A2IrO3

Journal Article · Fri Mar 23 04:00:00 EDT 2012 · Physical Review Letters

DOI:https://doi.org/10.1103/PhysRevLett.108.127203· OSTI ID:1044769

Singh, Y; Berlijn, T; Singh, Y; Manni, S; Reuther, J; Thomale, R; Ku, W; Trebst, S; Gegenwart, P

Combining thermodynamic measurements with theoretical calculations we demonstrate that the iridates A{sub 2}IrO{sub 3} (A = Na, Li) are magnetically ordered Mott insulators where the magnetism of the effective spin-orbital S = 1/2 moments can be captured by a Heisenberg-Kitaev (HK) model with interactions beyond nearest-neighbor exchange. Experimentally, we observe an increase of the Curie-Weiss temperature from {Theta} {approx} -125 K for Na{sub 2}IrO{sub 3} to {Theta} {approx} -33 K for Li{sub 2}IrO{sub 3}, while the ordering temperature remains roughly the same T{sub N} {approx} 15 K. Using functional renormalization group calculations we show that this evolution of {Theta} and T{sub N} as well as the low temperature zigzag magnetic order can be captured within this extended HK model. We estimate that Na{sub 2}IrO{sub 3} is deep in a magnetically ordered regime, while Li{sub 2}IrO{sub 3} appears to be close to a spin-liquid regime.

• Research Organization: BROOKHAVEN NATIONAL LABORATORY (BNL)
• Sponsoring Organization: USDOE SC OFFICE OF SCIENCE (SC)
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 1044769
• Report Number(s): BNL--98050-2012-JA; KC0202030
• Journal Information: Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 12 Vol. 108; ISSN 0031-9007; ISSN PRLTAO
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
FUNCTIONALS
MAGNETISM
RENORMALIZATION
THERMODYNAMICS