Zobrazeno 1 - 10
of 103
pro vyhledávání: '"Knetter C"'
Publikováno v:
Phys. Rev. Lett. 90, 167201 (2003)
In the two-leg S=1/2 ladders of Sr_14Cu_24O_41 a modulation of the exchange coupling arises from the charge order within the other structural element, the CuO_2 chains. In general, breaking translational invariance by modulation causes gaps within th
Externí odkaz:
http://arxiv.org/abs/cond-mat/0210092
Publikováno v:
Acta Phys. Pol. B 34, 1481 (2003)
We present a novel extrapolation scheme for high order series expansions. The idea is to express the series, obtained in orders of an external variable, in terms of an internal parameter of the system. Here we apply this method to the 1-triplet dispe
Externí odkaz:
http://arxiv.org/abs/cond-mat/0208358
Autor:
Grueninger, M., Windt, M., Nunner, T., Knetter, C., Schmidt, K. P., Uhrig, G. S., Kopp, T., Freimuth, A., Ammerahl, U., Buechner, B., Revcolevschi, A.
Magnetic excitations in two-leg S=1/2 ladders are studied both experimentally and theoretically. Experimentally, we report on the reflectivity, the transmission and the optical conductivity sigma(omega) of undoped La_x Ca_14-x Cu_24 O_41 for x=4, 5,
Externí odkaz:
http://arxiv.org/abs/cond-mat/0109524
Autor:
Grueninger, M., Windt, M., Nunner, T., Knetter, C., Schmidt, K. P., Uhrig, G. S., Kopp, T., Freimuth, A., Ammerahl, U., Buechner, B., Revcolevschi, A.
Transmission and reflectivity of La_x Ca_14-x Cu_24 O_41 two-leg spin-1/2 ladders were measured in the mid-infrared regime between 500 and 12000 1/cm. This allows us to determine the optical conductivity sigma_1 directly and with high sensitivity. He
Externí odkaz:
http://arxiv.org/abs/cond-mat/0108437
Publikováno v:
Phys. Rev. Lett. 87, 167204
Spectral densities are computed in unprecedented detail for quantum antiferromagnetic spin 1/2 two-leg ladders. These results were obtained due to a major methodical advance achieved by optimally chosen unitary transformations. The approach is based
Externí odkaz:
http://arxiv.org/abs/cond-mat/0106077
Autor:
Windt, M., Grueninger, M., Nunner, T., Knetter, C., Schmidt, K., Uhrig, G. S., Kopp, T., Freimuth, A., Ammerahl, U., Buechner, B., Revcolevschi, A.
Publikováno v:
Phys. Rev. Lett. 87, 127002 (2001)
Phonon-assisted 2-magnon absorption is studied at T=4 K in the spin-1/2 two-leg ladders of Ca_14-x La_x Cu_24 O_41 (x=5 and 4) for polarization of the electrical field parallel to the legs and the rungs, respectively. Two peaks at about 2140 and 2800
Externí odkaz:
http://arxiv.org/abs/cond-mat/0103438
Publikováno v:
Phys.Lett. B358 (1995) 87-94
Application of a Stueckelberg transformation allows one to connect various Lagrangians which have been independently proposed for non-standard couplings. We discuss the reduction of the number of independent parameters in the Lagrangian and compare s
Externí odkaz:
http://arxiv.org/abs/hep-ph/9506472
Publikováno v:
Z.Phys. C67 (1995) 109-114
Based on the observables $\MW$, $\Gamma_l$, $\bar\sw^2(\MZ^2)$, we evaluate the parameters $\Delta x, \Delta y$ and $\varepsilon$ at one-loop level within an electroweak massive vector-boson theory, which does not employ the Higgs mechanism. The theo
Externí odkaz:
http://arxiv.org/abs/hep-ph/9406378
Publikováno v:
Z.Phys. C59 (1993) 109-117
The BESS model is the Higgs-less alternative to the standard model of electroweak interaction, based on nonlinearly realized spontaneous symmetry breaking. Since it is nonrenormalizable, new couplings (not existing in the SM) are induced at each loop
Externí odkaz:
http://arxiv.org/abs/hep-ph/9212291
Publikováno v:
Int. J. Mod. Phys. A9 (1994) 5313
The BESS model is the Higgsless alternative to the standard model of electroweak interaction with nonlinear realized spontaneous symmetry breaking. Since it is non-renormalizable new couplings (not existing in the SM) are induced at each loop order.
Externí odkaz:
http://arxiv.org/abs/hep-ph/9208225