Zobrazeno 1 - 10
of 363
pro vyhledávání: '"Becca F"'
Publikováno v:
PRL 101, 117204 (2008)
The effect of a magnetic field on a gapped quantum magnet is described within the framework of the Quantum Dimer Model. A minimal model describing the proliferation of itinerant spinons above a critical field is proposed and investigated by Lanczos e
Externí odkaz:
http://arxiv.org/abs/0806.3486
Publikováno v:
Phys. Rev. B 78, 045114 (2008)
We present a method to compute pairing fluctuations on top of the Gutzwiller approximation (GA). Our investigations are based on a charge-rotational invariant GA energy functional which is expanded up to second order in the pair fluctuations. Equatio
Externí odkaz:
http://arxiv.org/abs/0803.4051
Publikováno v:
Phys. Rev. Lett. 100, 016405 (2008)
We present a theory of the dynamical two-particle response function in the Hubbard model based on the time-dependent Gutzwiller approximation. The results are in excellent agreement with exact diagonalization on small clusters and give reliable resul
Externí odkaz:
http://arxiv.org/abs/0706.1424
We discuss how orbital degeneracy, which is usually removed by a cooperative Jahn-Teller distortion, could under appropriate circumstances lead rather to a Resonating Valence Bond spin-orbital liquid. The key points are: i) The tendency to form spin-
Externí odkaz:
http://arxiv.org/abs/cond-mat/0609455
Publikováno v:
Phys. Rev. B 72, 024448 (2005)
Using exact diagonalizations, Green's function Monte Carlo simulations and high-order perturbation theory, we study the low-energy properties of the two-dimensional spin-1/2 compass model on the square lattice defined by the Hamiltonian $H = - \sum_{
Externí odkaz:
http://arxiv.org/abs/cond-mat/0501708
Publikováno v:
Phys. Rev. B 69, 155113 (2004)
We use a spin-rotational invariant Gutzwiller energy functional to compute random-phase-approximation-like (RPA) fluctuations on top of the Gutzwiller approximation (GA). The method can be viewed as an extension of the previously developed GA+RPA app
Externí odkaz:
http://arxiv.org/abs/cond-mat/0311128
We study the thermal properties of the classical antiferromagnetic Heisenberg model with both nearest ($J_1$) and next-nearest ($J_2$) exchange couplings on the square lattice by extensive Monte Carlo simulations. We show that, for $J_2/J_1 > 1/2 $,
Externí odkaz:
http://arxiv.org/abs/cond-mat/0307431
We study a chiral spin liquid wave function defined as a Gutwziller projected BCS state with a complex pairing function. After projection, spontaneous dimerization is found for any odd but finite number of chains, thus satisfying the Lieb-Schultz-Mat
Externí odkaz:
http://arxiv.org/abs/cond-mat/0306732
Autor:
Kodama, K., Takigawa, M., Horvatic, M., Berthier, C., Kageyama, H., Ueda, Y., Miyahara, S., Becca, F., Mila, F.
Publikováno v:
Science vol. 298, page 395, year 2002
We report the observation of magnetic superstructure in a magnetization plateau state of SrCu2(BO3)2, a frustrated quasi-two-dimensional quantum spin system. The Cu and B nuclear magnetic resonance (NMR) spectra at 35 mllikelvin indicate an apparentl
Externí odkaz:
http://arxiv.org/abs/cond-mat/0210294
Publikováno v:
Phys. Rev. B 67, 085108 (2003)
We present a detailed study of the time-dependent Gutzwiller approximation for the Hubbard model. The formalism, labelled GA+RPA, allows us to compute random-phase approximation-like (RPA) fluctuations on top of the Gutzwiller approximation (GA). No
Externí odkaz:
http://arxiv.org/abs/cond-mat/0209351