Hysteresis in core/shell nanowire with mixed spin Ising

Abstract

In this work, Monte Carlo simulations (MCS) based on Metropolis algorithm were performed to study the hysteresis loops and coercive field of a core/shell nanowire with spins S = ± 5 2 , ± 3 2 , ± 1 2 and σ = ± 3 2 , ± 1 2 , respectivility, considering an Ising ferrimagnetic system. The influence of nearest neighbors exchange interactions and crystal field anisotropy on hysteresis and coercive field behaviors of the system has been analyzed. The calculations were performed using a single-spin flip algorithm. In each spin-flip attempt, we randomly choose a site. The results show that, for a system without anisotropy triple hysteresis loops appear for certain values. The plateaus in hysteresis loops are due to the values of the spins projections. The change of the values for anisotropy influence the shape of the hysteresis loops without present triple hysteresis loops. Also, the effect of the anisotropy in the coercive field was analyzed, where the coercive field present enhanced for certain range of the temperatures. Finally, for high values of the applied external magnetic field, the Zeeman effect takes control over the system.

Magnetic properties and hysteresis behavior of a ferrimagnetic mixed spin-3/2 and spin-5/2 Ising nanowire

“…Another interesting system is the Ising model with mixed half-integer spins S = 3/2 and S = 5/2 which has been studied theoretically by several methods, such as the effective field theory with correlations (Zhang et al , 2005), the exact recursion relations on the Bethe lattice (Albayrak and Yigit, 2006), the mean field approximation (Mohamad, 2013) and the MCS (Vélez et al , 2014; De La Espriella and Buendía, 2011); all these works exhibit a rich critical behavior in phase diagrams, especially the first-order and second-order phase transitions and the compensation temperatures. In addition, there are several experimental studies for isoelectric compounds and structural species which are systems with mixed spins (3/2 and 5/2), such as Cs 2 Mn II [V II (CN) 6 ] (Entley and Girolami, 1995), CsMn II [Cr III (CN) 6 ]H 2 O (Babel, 1986) and Mn II [Mn IV (CN) 6 ] x H 2 O (Klenze et al , 1980); these three compounds have d 5 Mn II centers and d 3 metal centers (V II , Cr III and Mn IV ), and the magnetic transition temperatures obtained are about 125 K, 90 K and, 49 K respectively. Furthermore, another experimental works have shown that the mixed spin-3/2 and spin-5/2 systems are responsible for unusual magnetic properties of the bacterial heme proteins known as the ferricytochromes c' (Maltempo, 1974).…”