Dresden 2009 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
TT: Fachverband Tiefe Temperaturen
TT 38: Correlated Electrons: Low-dimensional Systems - Models 1
TT 38.5: Vortrag
Donnerstag, 26. März 2009, 10:45–11:00, HSZ 301
Temperature dependent optical conductivity in frustrated chain cuprates near the ferromagnetic-spiral critical point — •Stefan-Ludwig Drechsler1, Jiri Malek1,2, Satoshi Nishimoto1, Helge Rosner3, Ulrike Nitzsche1, Roman Kuzian1,4, and Helmut Eschrig1 — 1IFW-Dresden, Germany — 2Inst. Phys. ASCR, Czech Republic — 3MPI-CPfS Dresden, Germany — 4Inst. of Mat. Sci. Problems, Kiev, Ukraine
The optical conductivity σ(ω) [1] and the loss function of EELS are calculated at finite temperature T for CuO2 chain clusters within a five-band O2pCu3d-Hubbard model using exact diagonalizations and the DMRG-technique. Data at T = 300 K for Li2CuO2 are reanalyzed within this approach. The relative weights of Zhang-Rice singlet and triplet charge excitations near 2.7 and 4 eV, respectively, depend strongly on T, and a rather dramatic dependence of σ(ω) on the ratio of the 1st to 2nd neighbor exchange integrals is predicted. From our results information about exchange interactions for frustrated edge-shared cuprates can be obtained from T-dependent optical spectra. The obtained exchange integrals compare well with results of LDA+U calculations. Our results are also relevant for magnetically weakly coupled unfrustrated wide-gap insulators in general.
[1] J. Málek et al., PRB 78 060508(R) (2008).