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Temperature-dependent correlation effects in strontium iridate Sr2IrO4

Cyril Martins, CEA DAM Ile-de-France (Bruyères le Châtel)

Séminaire LCPQ

Salle de séminaire IRSAMC

Quite generally, the relatively extended d-orbitals of 5d transition metal oxides are less affected by electronic Coulomb correlations than their 3d counterparts. Strontium iridate (Sr2IrO4 ), however, is an example where the cooperative effect of spin-orbit coupling, lattice distortions and Coulomb correlations drives the compound insulating, with one hole in the t2g manifold of projected j eff = 1/2 total angular momentum. Whereas the low-temperature phase of this compound exhibits non-collinear magnetic order, the high-temperature phase is paramagnetic and paraorbital, leading to the notion of a “spin-orbitally ordered j eff = 1/2 Mott insulator†[1].

Interestingly, optical conductivity spectra σ(ω) display a strong decrease of the Mott gap with increasing temperature [3]. While the temperature-dependent electronic structure of the low-temperature
magnetically ordered phase has attracted much attention recently, the situation in the high-temperature paramagnetic phase is less clear. In this talk, we present an ab initio study of temperature-dependent correlation effects in Sr2IrO4, in comparison to angle-resolved photoemission and time-resolved photoemission spectra [2].

[1] Cyril Martins, Markus Aichhorn, Loïg Vaugier, et Silke Biermann. Phys. Rev. Lett., 107 266404 (2011).
[2] Cyril Martins, Thomas Ayral, Luca Perfetti, Markus Aichhorn, et Silke Biermann. in preparation.
[3] S. J. Moon, Hosub Jin, W. S. Choi, J. S. Lee, S. S. A. Seo, J. Yu, G. Cao, T. W. Noh, et Y. S. Lee. Phys. Rev. B, 80 195110 (2009).