Antiferromagnetism in theS=12antiferromagnetic Heisenberg model on a two-dimensional square lattice

A Novel Structure for Optical Channel Drop Filter using Two-Dimensional Photonic Crystals with Square Lattice

In the present paper a novel structure for optical channel drop filter (CDF) based on photonic crystal ring resonator with circular core has been proposed. In order to design the proposed CDF, the plan wave expansion (PWE) method is applied for calculation of band structure and photonic band gap while the transmission characteristics of proposed CDF have been calculated using the finite differe...

Magnetic properties of the two-dimensional Heisenberg model on a triangular lattice

The spin Green’s function of the antiferromagnetic Heisenberg model on a triangular lattice is calculated using Mori’s projection operator technique. At T = 0 the spin excitation spectrum is shown to have gaps at the wave vectors of the classical Néel ordering. This points to the absence of the antiferromagnetic long-range order in the ground state. The calculated spin correlation on the neighb...

Random-exchange quantum Heisenberg antiferromagnets on a square lattice

Nicolas Laflorencie,1 Stefan Wessel,2 Andreas Läuchli,3 and Heiko Rieger4 1Department of Physics & Astronomy, University of British Columbia, Vancouver, B.C., Canada V6T 1Z1 2Institut für Theoretische Physik III, Universität Stuttgart, 70550 Stuttgart, Germany 3Institut Romand de Recherche Numérique en Physique des Matériaux, EPFL, 1015 Lausanne, Switzerland 4Theoretische Physik, Universität de...

Heisenberg Antiferromagnet on Square-Kagomé Lattice: Resonating Valence Bond Description

The Heisenberg antiferromagnet on the square-kagomé lattice

We discuss the ground state, the low-lying excitations as well as high-field thermodynamics of the Heisenberg antiferromagnet on the two-dimensional square-kagomé lattice. This magnetic system belongs to the class of highly frustrated spin systems with an infinite non-trivial degeneracy of the classical ground state as it is also known for the Heisenberg antiferromagnet on the kagomé and on the...