arXiv subjects

George A. Sawatzky

Publications and source records attributed to George A. Sawatzky.

58 records · Page 4Linked to original sources

arXiv2007

Origin of charge density wave in the coupled spin ladders in Sr$_{14-x}$Ca$_x$Cu$_{24}$O$_{41}$

We formulate a d-p multiband charge transfer model for Cu$_2$O$_5$ coupled spin ladders, relevant for Cu$_2$O$_3$ plane of Sr$_{14-x}$Ca$_x$Cu$_{24}$O$_{41}$, and solve it using Hartree-Fock approximation. The results explain that (i) the charge density wave (CDW) with its periodicity dependent on doping is stabilized by purely electronic many-body interactions in a single spin ladder and (ii) the inclusion of the interladder interactions favors (disfavors) the stability of the CDW with odd (even) periodicity, respectively. This stays in agreement with recent experimental results and suggests the structure of the minimal microscopic model which should be considered in future more sophisticated studies.

cond-mat.str-el↗

arXiv2006

Charge density wave in the spin ladder of Sr$_{14-x}$Ca$_x$Cu$_{24}$O$_{41}$

We consider a multiband charge transfer model for a single spin ladder describing the holes in Sr$_{14-x}$Ca$_x$Cu$_{24}$O$_{41}$. Using Hartree-Fock approximation we show how the charge density wave, with its periodicity dependent on doping as recently observed in the experiment, can be stabilized by purely electronic many-body interactions.

cond-mat.str-el↗

arXiv2006

The Green's Function of the Holstein Polaron

We present a novel, highly efficient yet accurate analytical approximation for the Green's function of a Holstein polaron. It is obtained by summing all the self-energy diagrams, but with each self-energy diagram averaged over the momenta of its free propagators. The result becomes exact for both zero bandwidth and for zero electron-phonon coupling, and is accurate everywhere in the parameter space. The resulting Green's function satisfies exactly the first six spectral weight sum rules. All higher sum rules are satisfied with great accuracy, becoming asymptotically exact for coupling both much larger and much smaller than the free particle bandwidth. Comparison with existing numerical data also confirms this accuracy. We use this approximation to analyze in detail the redistribution of the spectral weight as the coupling strength varies.

cond-mat.str-el↗

arXiv2001

Absence of magic fillings of carrier-doped C$_{60}$ in a field-effect transistor

Motivated by recent experiments of carrier-doped C$_{60}$ in a field-effect transistor (FET), effects of spatial single particle potential variations on Mott-Hubbard (MH) insulators are studied theoretically. It is shown that the presence of strong random potentials leads to a reduced dependence of electronic properties on band fillings and to disappearance of the MH insulating behavior at integer fillings. A simple physical picture to explain this behavior is given using a notion of self-doping of the MH insulator. Our results have important implications on some of the puzzling observations of carrier-doped C$_{60}$ in the FET. It is also discussed that the FET configuration with Al{$_2$}O{$_3$} dielectric provides an ``ideal'' system with strong disorders.

cond-mat.str-el↗