Glauber-type Stochastic Dynamics Research Articles

Kinetic phase phenomena of model with the chemical formula [formula omitted] on honeycomb lattice

We investigate the ferromagnetic–ferrimagnetic ternary alloy model with the chemical formula ABpC1−p with mean-field theory based on Glauber-type stochastic dynamics, namely dynamic mean-field theory, on a honeycomb lattice consisting of spins SiA=1/2, SjB=3/2 and SjC=5/2. The model includes a selective site disorder, meaning that SiA can randomly have SjC as its nearest neighbor or SjB with probability (1−p). The mean-field dynamic equations were obtained and numerically solved. To identify the type of dynamic phase transitions (first- or second-order), the thermal behavior of dynamic magnetizations was examined. For specified values of the crystal field parameter, exchange interaction parameter, and concentration ratio, the phase diagrams are calculated in the (d−T) and (T−h) planes. The system's fundamental and mixed-phase areas were identified. The system displayed A,TP,QP,Z special points and dynamic tricritical points. It was found that the content of the ternary alloy continuously affected the critical temperature in our dynamic system. Reliable agreements are observed when our findings are compared to those in the literature.

Non-equilibrium magnetic properties of a mixed spin (1/2, 1) Ising graphene nanoisland.

Based on Glauber-type stochastic dynamics intertwined with mean field theory, we have investigated a graphene nanoisland's out-of-equilibrium magnetic and thermomagnetic behaviors with a mixed ferrimagnetic spin (1/2, 1) configuration in the presence of an oscillating magnetic field. The influence of the oscillating external magnetic field, single-ion anisotropy and temperature on the dynamic magnetic properties (dynamic phase transitions, hysteresis loop areas, correlations, and phase diagrams) of the system is studied in detail. The results illustrate that single ion anisotropy and the magnetic field play important roles in the system's dynamic order parameters, phase transitions and phase diagrams. Dynamic phase diagrams display some dynamic special points such as dynamic tricritical points, quadruple points and some sort of reentrant phenomena, which strongly depend on interaction parameters. Our predicted results may provide a reference for future experimental and theoretical studies of the nanostructures.

Dynamic magnetic properties in 2-dimensional kinetic spin-7/2 Ising system

The dynamic magnetic properties, such as dynamic phase transitions (DPTs) and dynamic phase diagrams (DPDs), are reported in 2-Dimensional (2D) kinetic spin-7/2 Ising system under an oscillating external magnetic field. With this aim in mind, the Glauber type stochastic dynamics are utilized to obtain the mean-field dynamic equation determining kinetic system's motion on a square lattice. The obtained mean-field dynamic equation is solved numerically. First, to observe the kinetic system's dynamic phases, the average sublattice magnetization time variations are investigated. After that, to determine the type (first- or second-order) of the DPTs and obtain the DPTs, the dynamic sublattice magnetizations' thermal behavior is examined. Finally, the DPDs are calculated in two different planes. The DPDs contains paramagnetic (P), ferromagnetic-1/2 (F1/2), ferromagnetic-7/2 (F7/2) fundamental phases and six mixed regions (or phases) as well as private points and reentrant phenomena. It has been appeared that the DPTs and DPDs are strongly dependent on the interaction parameters.

Dynamic critical phenomena in a multilayer Ising system

Using the mixed-spin system, we precisely calculate the dynamic critical phenomena, namely dynamic compensation behaviors, dynamic phase diagrams and dynamic hysteresis loops in a multilayer Ising system that composes of four monoatomic layers. As the method, we use the mean-field theory based on Glauber-type stochastic dynamics. It is found that the Hamiltonian parameters have a strong effect on the dynamic critical phenomena. The system displays the P-, Q-, R-, and S-type compensations and multiple hysteresis loop behaviors. The results are qualitatively consistent with those of some theoretical and experimental studies.

Dynamic magnetic hysteresis loop behaviors of a mixed spin (2, 5/2) Ising model on two interpenetrating square lattices

We investigate dynamic magnetic hysteresis loop (DMHL) behaviors of a mixed spin (2, 5/2) Ising model on two interpenetrating square lattices under an oscillating magnetic field within the effective-field theory based on Glauber–type stochastic dynamics. We study the DMHL properties for various values of reduced temperatures (T/zJ), crystal-field interaction (D/zJ) and frequency () of the magnetic field. We also examine T/zJ, D/zJ and dependences of the coercive fields (CFs) and remanent magnetizations (RMs). We found that for very low and high values of T/zJ and D/zJ, the hysteresis loop area is narrower and thinner that correspond soft magnets that desirable for transformers and motor cores and AC applications. We observed that for high values of the hysteresis loop areas are wide and big that corresponds hard magnets which can be useful for permanent magnets, magnetic recording, small motors and magnetic locks. We also found that the DMHLs, CFs and RMs behaviors are in quantitatively good agreement with some theoretical for Ising systems and experimental works for magnetic materials, such as cobalt films, Fe films and some magnetic nanomaterials.

Nonequilibrium magnetic properties of the mixed spin (1/2, 1) Ising nanowire with core-shell structure

Abstract The nonequilibrium magnetic properties (phase transition temperatures, phase diagrams, hysteresis loop areas and correlations) are investigated in the kinetic mixed spin (1/2, 1) Ising nanowire system under the time varying magnetic field. The Glauber-type stochastic dynamics are employed to construct the set of mean field dynamic equations. The time variation of the core/shell magnetizations and the thermal behavior of the dynamic core/shell magnetizations are examined, extensively. The dynamic core/shell magnetizations, hysteresis loop areas and correlations are studied as a function of temperature in order to characterize the nature (continuous or discontinuous) of the phase transitions as well as to find the dynamic phase transition temperatures. The dynamic phase diagrams are presented in the magnetic field amplitude and temperature plane. The dynamic phase diagrams exhibit paramagnetic (p), ferrimagnetic (i), nonmagnetic (nm) phases, three mixed regions, (i + nm), (i + p) and (nm + p). The dynamic phase diagrams contain a dynamic tricritical point and reentrant phenomena, which strongly depend on interaction parameters.

Dynamic magnetic properties of a hexagonal Ising nanowire system with higher-spin

ABSTRACTAppling the framework of dynamic mean-field theory based on the Glauber-type stochastic dynamics, we study the dynamic magnetic hysteresis loop (DMHL) properties of the hexagonal nanowire system with spin-2 Ising particles. We investigate the DMHL behaviors for various values of reduced temperatures and interaction parameters. We also examine the reduced temperature and interaction parameters dependences of the coercive fields and remanent magnetizations. The obtained results are compared with some theoretical and experimental works and find a quantitatively good agreement with some theoretical and experimental works.

Dynamic Phenomena in Mixed Spin-1 and Spin-1/2 Ising Bilayer System: Effective-Field Theory Based on Glauber Type Stochastic Dynamics

The dynamic compensation and dynamic hysteresis features of the mixed bilayer Ising system (MBIS) consist of spin-1 and spin-1/2 on a bilayer square lattice and have been studied extensively with the use of the effective-field theory and Glauber type stochastic dynamic. Firstly, the thermal variations of the total magnetization were investigated in order to find the compensation types of the MBIS. The six compensation types were found to be the Q-, R-, P-, N-, S-, and L-types. Then, the effects of the temperature, interlayer coupling constant, crystal field, and oscillating field frequency on the dynamic magnetic hysteresis properties were widely studied.

An investigation of competition on the dynamic magnetic properties of the core/shell nanowire

In this study, we investigate the dynamic magnetic properties of Ising-type core/shell nanowires (NW) for different spin systems. The model of NW X(Spin-1/2)@Y with Y = Spin-1/2, Spin-1 and Spin-3/2 are considered for discussing an effect of the nature of shell particle on the dynamic properties. The mean-field theory and Glauber-type stochastic dynamics have been successfully applied to this, and the results of the dynamic magnetic properties for the core/shell NW are obtained. Different shell spin states are employed to the analysis of dynamic magnetic behavior for core/shell NW. Results of numerical calculation for the magnetization and coercivity curves are discussed for the effect of shell particles, shell interaction and oscillating field frequency. All results present that dynamic magnetic properties of the NW strongly dependent on the shell particle and the shell interaction.

Dynamic magnetic and hysteretic properties of the different type core/shell nanostructures: the effect of geometry of wire shape

ABSTRACTIn the present study, we examine by comparison the dynamic magnetic and hysteretic properties of nanostructures with different magnetic core/shell particles confined within a shape structure of the wire. The model of nanostructures with core = spin-1 and shell = spin-3/2, namely cylindrical, cubic and hexagonal nanowire, is proposed for studying the effect of the geometry of wire shape on the magnetic and hysteretic properties. The results were obtained by mean-field theory as well as Glauber-type stochastic dynamics, and focused the response to thermal and hysteretic behaviours of systems. All results display dynamic magnetic properties of the nanostructure strongly dependent on the geometry of wire shape. Moreover, temperature and crystal field are proposed as the important factors affecting the dynamic properties of wire systems.

Kinetic phase transitions for the semi-infinite Ising model with bulk S [formula omitted] 1 and a free surface [formula omitted] under an oscillating magnetic field

The kinetics of the semi-infinite Ising model in the presence of a time dependent oscillating external field is studied within the framework of the mean-field approach. We use the Glauber-type stochastic dynamics to describe the time evolution of this system. We present a variety of phases in semi infinite cubic ferromagnet with spin 1 at the bulk and spin 12at the surface. The obtained Phase diagrams contains surface ordered phase (BP, SF), completely ordered phase (BF, SF) and completely disordered phase (BP, SP) that strongly depend on interaction parameters. The first or second order nature of the transitions is characterized by studying the thermal behaviors of the dynamic magnetizations. Furthermore, the system exhibits dynamical tricritical phenomenon. The magnetizations and phase space trajectories are given and discussed.

Influences of Crystal-Field and Interlayer Coupling Interactions on Dynamic Phase Diagrams of a Mixed-Spin (3/2,2) Bilayer System**Supported by Erciyes University Research Fund under Grant No. FBA-2016-6324

Influences of crystal-fields (DA and DB) and interlayer coupling interactions (J3) on dynamic magnetic critical behaviors of a mixed-spin (3/2, 2) bilayer system under an oscillating magnetic field are investigated by the Glauber-type stochastic dynamics based on the mean-field theory. For this purpose, dynamic phase diagrams are constructed in the reduced temperature and magnetic field amplitude plane for the ferromagnetic/ferromagnetic (FM/FM), antiferromagnetic/ferromagnetic (AFM/FM) and AFM/AFM interactions in detail. We observe that the influences of DA, DB and J3 interactions parameters on the behavior of the dynamic phase diagrams are very much.

Dynamic hysteresis loops of the spin-2 bilayer Ising model

Based on the mean-field theory and Glauber-type stochastic dynamics, the dynamic hysteresis loops (DHLs) of the spin-2 Ising model are studied on the bilayer square lattice. The DHLs are given for different values of temperature, crystal-field, exchange interaction and oscillating field frequency. It is found that the physical parameters have a strong effect on the shape and number of the DHLs. The results are compared with some theoretical and experimental works and found in a qualitatively good agreement.

Random Crystal Field Effect on the Kinetic Spin-1 and Spin-3/2 Under a Time-Dependent Oscillating Field Phase Transitions

The effect of random crystal field on the stationary states of the kinetic spin-1 and spin-3/2 Blume-Capel model is investigated within the framework of the mean field approach. The Glauber-type stochastic dynamics is used to describe the time evolution of the system which is subjected to a time-dependent oscillating external magnetic field. The model exhibits first- and second-order transitions as well as dynamical tricritical, triple and an isolated critical end points. We found that the system displays reentrant phenomenon for both α = 0 and α > 0. Moreover, the system exhibits in the phase space a fixed points and limit cycles with circle, elliptic and parallelogram shapes.

Dynamic calculations of the core/shell structured Ising-type endohedral fullerenes: The effect of core and core/shell interaction

In this study, we examine by comparing the dynamic magnetic and hysteretic properties of Ising-type endohedral fullerene (EF) with various dopant magnetic particles confined within a spherical cage. The model of EF X@C[Formula: see text] with X = spin-1/2, spin-1 and spin-3/2 is proposed to study the effect of the nature of core particle on the magnetic properties. The results were obtained by mean-field theory as well as Glauber-type stochastic dynamics, and focused on the response of thermal and hysteretic behaviors of systems. The system exhibits second- and first-order phase transitions. In three different core cases, the system also exhibits type-II superconductivity behavior with a dynamic hysteresis curves of the core. All results display magnetic properties of the EF which strongly depend on the nature of core particle. Moreover, core particle and core/shell (C–S) interaction are proposed as the basic factors affecting the magnetic properties of EF system.

Dynamic hysteresis behaviors in the kinetic Ising system on triangular lattice

ABSTRACTWe studied dynamic hysteresis behaviors of the spin-1 Blume-Capel (BC) model in a triangular lattice by means of the effective-field theory (EFT) with correlations and using Glauber-type stochastic dynamics. The effects of the exchange interaction (J), crystal field (D), temperature (T) and oscillating frequency (w) on the hysteresis behaviors of the BC model in a triangular lattice are investigated in detail. Results are compared with some other dynamic studies and quantitatively good agreement is found.

Dynamic magnetic behaviors in the Ising-type nanowire with core-shell single-ion anisotropies under a time-dependent oscillating external magnetic field

In the present study, the Ising-type nanowire with core-shell single-ion anisotropies is studied to investigate the dynamic magnetic behaviors such as the dynamic magnetizations, hysteresis loop areas and dynamic correlations. Thermal and parametric dependences of them are obtained by utilize the effective-field theory with correlations and the Glauber-type stochastic dynamics approach. Thanks to, the nature (first-or second-order) of the dynamic transitions are characterized and the dynamic phase transition temperatures are determined. The effect of interaction parameters on the dynamic phase diagrams is also studied.

Dynamic Magnetic Features of the Mixed Ising System on the Bilayer Square Lattice

In order to study the dynamic magnetic features of the mixed spin-1 and spin-5/2 Ising system, we have used the mean-field theory (MFT) based on the Glauber-type stochastic dynamics on the bilayer square lattice (BSL). By employing the Master equation, dynamic equations describing the behavior of the system are derived. The average order parameters and dynamic order parameters are studied for different values of exchange interactions, oscillating magnetic field, and temperature. The complete dynamic phase diagrams (DPDs) are obtained for the ferromagnetic/ferromagnetic (FM/FM), ferromagnetic/antiferromagnetic (FM/AFM), and antiferromagnetic/antiferromagnetic (AFM/AFM) interactions in the different planes, and the role of the interaction in the Hamiltonian on the DPDs is explored. It is found that the DPDs display richer dynamic behavior for this mixed Ising system.

Kinetic Phase Transition in the Semi-infinite Spin-1 Ising Model Under a Periodically Oscillating Magnetic Field

The kinetics of the semi-infinite Ising model in the presence of a time-dependent oscillating external field is studied within the framework of the mean-field approach. We use the Glauber-type stochastic dynamics to describe the evolution time of this system. We present a variety of phase in a semi-infinite cubic ferromagnet with spin-1 in two different, planes; phase diagrams contain (BF, S 1P, SP) phase, (BF, S 1F, SP) phase, completely ordered phase (BF, S 1F, SF) and completely disordered phase (BP, S 1P, SP), which strongly depend on interaction parameters. The nature first and second orders of the transitions is characterized by studying the thermal behaviors of the dynamic magnetizations. Furthermore, the system exhibits dynamical tricritical phenomenon and the reentrant behaviors. The magnetizations and phase space trajectories are given and discussed.

Dynamic Properties of Kinetic Spin-3/2 Ising Ferromagnetic Model in the Presence of the Crystal and External Oscillating Magnetic Fields

The kinetic spin-3/2 Ising system in the presence of crystal and external oscillating magnetic fields on the triangular lattice (TL) is examined within the mean-field approximation and the Glauber-type stochastic dynamics, namely dynamic mean-field approximation (DMFA). First, the dynamic equations describing the behavior of the system are derived for the TL. Then, the dynamic equations are solved numerically to obtain the dynamic hysteresis curves of the kinetic spin-3/2 Ising ferromagnetic system, which strongly depend on the Hamiltonian parameters. Moreover, the dynamic behaviors of the coercivity and remanent magnetizations are studied depending on the temperature, crystal field and frequency of the oscillating external magnetic field. Finally, the results are compared with some experimental and theoretical studies and a qualitatively good overall agreement is observed