Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 42: Correlated Electrons: Frustrated Magnets - Cu-based Systems & FeCr
TT 42.5: Vortrag
Mittwoch, 9. März 2016, 10:30–10:45, H18
Cu4(OH)6FBr - a structurally perfect spin-1/2 kagome system — •Bernd Wolf1, Elena Gati1, Nguyen Hieu Hoang1, Harald O. Jeschke2, Francesc Salvat-Pujol2, Roser Valenti2, John A. Schleuter3, and Michael Lang1 — 1Physics Institute, Goethe-University Frankfurt(M), Germany, — 2Institute for Theoretical Physics, Goethe-University Frankfurt(M), Germany, — 3Division of Materials Research, National Science Foundation, Arlington, Virginia, USA
Spin-1/2 kagome lattices have been intensively investigated in recent years since they support the formation of quantum spin liquids (QSL). A prominent example is the natural mineral herbertsmithite ZnCu3(OH)6Cl2 [1]. Here chemical modifications are difficult to realize and therefore new design strategies are necessary for synthesizing novel QSL. Cu4(OH)6FBr reflects such a novel approach [2] where a structurally perfect kagome arrangement is achieved. We present a detailed magnetic characterization of small single crystals of Cu4(OH)6FBr. Measurements of the magnetization and susceptibility down to 2 K and up to 5 T reveal indications for two dominant magnetic couplings of different sign and an antiferromagnetic transition at TN = 15 K exhibiting a weak ferromagnetic component. The experimental findings are in good agreement with the results of density functional theory (DFT) calculations. In addition, we present thermal expansion measurements from which the pressure dependence of TN is determined.
T.-H. Han et al., Nature 492, 406 (2012).
H. O. Jeschke et al., PRB 92, 094417 (2015)