Ground State, Magnetization Process and Bipartite Quantum Entanglement of a Spin-1/2 Ising–Heisenberg Model on Planar Lattices of Interconnected Trigonal Bipyramids

The ground state, magnetization scenario and the local bipartite quantum entanglement of a mixed spin-1/2 Ising–Heisenberg model in a magnetic field on planar lattices formed by identical corner-sharing bipyramidal plaquettes is examined by combining the exact analytical concept of generalized decoration-iteration mapping transformations with Monte Carlo simulations utilizing the Metropolis algorithm. The ground-state phase diagram of the model involves six different phases, namely, the standard ferrimagnetic phase, fully saturated phase, two unique quantum ferrimagnetic phases, and two macroscopically degenerate quantum ferrimagnetic phases with two chiral degrees of freedom of the Heisenberg triangular clusters. The diversity of ground-state spin arrangement is manifested themselves in seven different magnetization scenarios with one, two or three fractional plateaus whose values are determined by the number of corner-sharing plaquettes. The low-temperature values of the concurrence demonstrate that the bipartite quantum entanglement of the Heisenberg spins in quantum ferrimagnetic phases is field independent, but twice as strong if the Heisenberg spin arrangement is unique as it is two-fold degenerate.

Композиционный радиопоглощающий материал на основе резистивных квадратов

On the basis of the solution of the diffraction problem, the effective permittivity of the composite material consisting of alternating planar lattices of resistive squares displaced relative to each other and located in the dielectric layer is calculated. It is shown that the dispersion has a relaxation character. It is shown that it is possible to vary the dispersion characteristic over a wide range by varying the parameters of the structure. It is shown that the mutual displacement of lattices significantly changes the dispersion of the dielectric constant of the structure. The ratio of the wavelength to the period of the structure is estimated, at which the homogenization procedure is adequate.