Papers by Marcello Silva Neto
Bulletin of the American …, 2010
We study the ground state of the one-dimensional symmetric periodic Anderson model for various ba... more We study the ground state of the one-dimensional symmetric periodic Anderson model for various band fillings, n, and for several values of the on-site repulsion U , and of the hybridization V between the c-and f-bands. Through the Density Matrix Renormalization Group (DMRG) method, we calculate magnetic correlation functions, and their structure factors, charge and pairing correlations, as well as inter-orbital correlations, such as ⟨c † f + h.c.⟩, ⟨S c • S f ⟩; we also obtain charge and spin gaps. The analysis of these quantities allows a thorough characterization of the system, which can be summarized in a phase diagram in the parameter space (U, V, n).
Physica B: Condensed Matter, 2006
We derive the long-wavelength non-linear sigma model for a two-dimensional Heisenberg system in t... more We derive the long-wavelength non-linear sigma model for a two-dimensional Heisenberg system in the presence of the Dzyaloshinskii-Moriya and pseudodipolar interactions. We show that the system is a non-conventional easy-axis antiferromagnet, displaying an anomalous coupling between the magnetic field and the staggered order parameter. Our results are in good agreement with recent experimental data for undoped La2CuO4 compounds.
Submitted for the MAR07 Meeting of The American Physical Society Competing Impurities in an Antif... more Submitted for the MAR07 Meeting of The American Physical Society Competing Impurities in an Antiferromagnetic Background. LYUDMYLA ADAMSKA, Goteborg University, MARCELLO B. SILVA NETO, Stuttgart University, CRISTIANE MORAIS SMITH, Utrecht University-We study the order-from-disorder transition and reentrant magnetism in a doped crystal La 2−x Sr x Cu 1−z Zn z O 4 within the framework of a long-wavelength nonlinear sigma model that properly incorporates the Dzyaloshinskii-Moriya and XY anisotropies. The effect of doping La 2 CuO 4 with nonmagnetic impurities, such as Zn, is considered according to classical percolation theory, while the effect of the Sr-doped charge carriers is described as a dipolar frustration of the antiferromagnetic order. We derive the expressions for several magnetic, thermodynamic, and spectral properties of the system, such as the Néel temperature, the spin-stiffness, and the anisotropy gaps, as well as their evolution with both Zn and Sr doping for cases of ballistic and diffusive vacancies. We solve the problem analytically in the limits of low and high temperatures. The connection to several experiments will be discussed [
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Papers by Marcello Silva Neto