Triangular array of interacting magnetic
nanoparticles
Márcio Santos and Wagner Figueiredo
Departamento de Física – UFSC
Walther Schwarzacher
H. H. Wills Physics Laboratory – University of Bristol
Abstract
We investigate through Monte Carlo simulations a system of
identical nanoparticles in a triangular lattice interacting via long range
dipolar forces. The particles also present a contribution to the energy
coming from the crystalline field where its magnitude is obtained from a
Gaussian distribution. The easy magnetization axes are randomly
oriented in the three-dimensional space. We determine the blocking
temperature of this system as a function of the ratio (a) between the
dipolar and crystal field energies. In order to do that, we apply a small
magnetic field on a sample of particles with an otherwise zero
magnetization. As we increase the temperature the particles become
unblocked and the magnetization reaches a maximum value that defines
the so-called blocking temperature. We also observe that at this
temperature, the susceptibility, specific heat and the fourth-order Binder
cumulant exhibit a maximum. For an in-plane applied magnetic field, we
determine the hysteresis curves as a function of the parameter a, and
we show that the coercive field presents a slight minimum as a function
of this parameter. We plotted the coercive field and remanence as a
function of temperature, and from these plots we can find the blocking
temperature of the system.