Magnetic and Critical Properties of Alternating Spin Heisenberg Chain in a Magnetic Field

Entanglement in the XZ spin chain model in the external magnetic field

The entanglement at zero-temperature is studied in a two-qubit XZ spin-1/2 chain model in anexternal magnetic field which is applied in the z direction. We have obtained an analytical relation forthe effect of the external magnetic field on the concurrence. It is shown that the ground state of thesystem depends on the strength of exchange coupling. We have shown that the analytical relation oft...

Thermal negativity in a two qubit XXX and XX spin chain model in an external magnetic field

In this paper we studied the thermal negativity in a two-qubit XX spin ½ chain model and XXX spin1/2 chain model(isotropic Heisenberg model)spin-1/2 chain subjected to an external magnetic field inz direction. We calculate analytical relation for the thermal negativity for two qubit XX and XXX spinchain models in the external magnetic field. Effects of the magnetic field and temperature on then...

Phase diagram and critical exponents of a dissipative Ising spin chain in a transverse magnetic field.

We consider a one-dimensional Ising model in a transverse magnetic field coupled to a dissipative heat bath. The phase diagram and the critical exponents are determined from extensive Monte Carlo simulations. It is shown that the character of the quantum phase transition is radically altered from the corresponding nondissipative model and the double well coupled to a dissipative heat bath with ...

Magnetic properties of the spin S = 1/2 Heisenberg chain with hexamer modulation of exchange.

We consider the spin-1/2 Heisenberg chain with alternating spin exchange in the presence of additional modulation of exchange on odd bonds with period 3. We study the ground state magnetic phase diagram of this hexamer spin chain in the limit of very strong antiferromagnetic (AF) exchange on odd bonds using the numerical Lanczos method and bosonization approach. In the limit of strong magnetic ...

Critical exponents of the Heisenberg spin chain.