Berlin 2012 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 40: Correlated Electrons: Low-dimensional Systems - Materials 3

TT 40.2: Vortrag

Donnerstag, 29. März 2012, 15:15–15:30, H 0104

DFT-based microscopic modeling for the spin-1/2 kagome systemherbertsmithite γ-Cu₃Zn(OH)₆Cl₂ — •Oleg Janson and Helge Rosner — Max-Planck-Institut für Chemische Physik fester Stoffe

Herbertsmithite γ-Cu₃Zn(OH)₆Cl₂ is a real material realization of the S = 1/2 kagome Heisenberg model. Extensive experimental characterization of this compound evidences the absence of long-range magnetic ordering down to 70 mK despite a leading exchange coupling of 190 K [1]. To account for the experimental data, a sizable structural Cu–Zn disorder was suggested. Very recent single crystal experiments revealed that these defects are confined to the interplane sites, while the magnetic kagome layers are almost defect-free [2].

Following the DFT-based study of the closely related compounds kapellasite α-Cu₃Zn(OH)₆Cl₂ and haydeeite α-Cu₃Mg(OH)₆Cl₂ [3], we apply our computational approach to the more complex case of herbertsmithite. Taking the idealized structure as a starting point, we investigate the influence of the Cu–Zn disorder onto the magnetic coupling regime. The numerical results are compared to the recent single-crystal experiments.

[1] J. S. Helton et al., Phys. Rev. Lett. 98, 107204 (2007).

[2] T. Imai et al., Phys. Rev. B 84, 020411(R) (2011).

[3] O. Janson, J. Richter, and H. Rosner, Phys. Rev. Lett. 101, 106403 (2008); J. Phys.: Conf. Ser. 145, 012008 (2009).