Narrow Results

Using the double-time Green’s function method in combination with the random phase approximation and Anderson–Callen approximation, we investigate the magnetic properties of the ferrimagnetic Heisenberg model on a decorated square lattice. The effects of nearest-neighbor interactions and single-ion anisotropy on the compensation temperature are explored. Our results indicate that the next-nearest-neighbor interaction and/or single-ion anisotropy are not a necessary condition of the appearance of compensation temperature. When considering only the nearest-neighbor interaction, the system can also exhibit a compensation temperature. By comparing the impact of the nearest-neighbor interaction and single-ion anisotropy on the sublattice magnetizations of the system, a general condition of the appearance of compensation temperature is claimed.

In this work, we have performed Monte Carlo simulations to study phase transitions in a mixed spin-1 and spin-3/2 Ising ferrimagnetic system on the square and cubic lattices and with two different single-ion anisotropies. These lattices are divided in two interpenetrating sublattices with spins $S^A=1$ (states $\pm 1$ and 0) on the sublattice $A$ and $S^B=3∕2$ (states $\pm 3∕2$, $\pm 1∕2$) on the sublattice $B$. We have used single-ion anisotropies $D_A$ and $D_B$ acting on the sites of the sublattice $A$ and $B$, respectively. We have determined the phase diagrams of the model in the temperature $T$ vs. the single-ion anisotropies strength $D_A$ and $D_B$ plane and shown that the system exhibits both second- and first-order phase transitions. This system also displays compensation points for some values of the anisotropies.

The behavior of the compensation of a mixed spin-1 and spin-1/2 Heisenberg ferrimagnetic system on a square lattice is investigated theoretically by a two-time Green-function technique which takes into account the quantum nature of Heisenberg spins. The model includes the nearest and next-nearest neighbor interactions between spins, a crystal field and an external magnetic field. This model can be relevant for understanding the magnetic behavior of bimetallic molecular ferrimagnets that are currently being synthesized by several experimental groups. We study the spin-wave spectra of the ground state and investigate the effects of the next-nearest neighbor interactions, a crystal field and an external magnetic field on the compensation temperature. It is found that a compensation point appears and it is basically unchanged when the next-nearest-neighbor interaction between spin-1/2 is taken into account and exceeds a minimum value for other values in Hamiltonian fixed. The compensation temperature is influenced by the next-nearest-neighbor interaction between spin-1 and the external magnetic field and it is disappearing as these parameters exceed the trivial values.

The magnetic properties of a mixed spin-2 and spin-5 / 2 Heisenberg ferrimagnetic system on a layered honeycomb lattice are investigated theoretically by a multisublattice Green-function technique which takes into account the quantum nature of Heisenberg spins. We calculate the magnetization and the compensation temperature and transition temperature of the system in an external magnetic field and in a zero external magnetic field, and find that the transition temperature of the system increases on the effect of an external magnetic field, the compensation point disappears when the single-ion anisotropy is not large and there are two compensation points when the anisotropy is large. We also calculate the initial susceptibilities of the system.

A mean-field approximation is developed for a decorated ferrimagnetic Ising model, in which the two magnetic atoms A and B have spins σ=1/2 and S=1, respectively. In this system, the exchange interaction between nearest-neighbors of atom B is taken into account. Some interesting phenomena, such as the appearance of three types of phase diagrams and the existence of one and two compensation points are found. Phase diagrams and temperature dependence of the magnetizations of the system are investigated in detail.

In this paper, the Monte Carlo simulation (MCS) and the mean field approximation (MFA) methods have been used to study the magnetic properties of double perovskite Ba₂CrMoO₆ in the framework of the Ising model, which is important for a better understanding of the magnetic behavior of this material. This compound is constituted of two magnetic cubic sublattices: one occupied by Mo${}^{5+}$ and other occupied Cr${}^{3+}$, the critical exponents and phase diagrams for this compound are determined. The critical behavior, compensation temperature and susceptibility are also determined.

In this study, the ground-state phase diagrams and magnetic properties of mixed spin ($S$-1, $\sigma$-7/2) of the monolayer coronene-like nanostructure have been investigated using Monte Carlo simulations (MCS) in the frame of the Blume Capel model. In the first part, ground-state phase diagrams have been analyzed in order to show the more stable configurations of spins corresponding to various planes. In addition, MCS is applied to study the behavior of the compensation and blocking temperatures by varying the exchange coupling interaction values. Finally, the hysteresis cycle behaviors have been investigated for selected values of exchange coupling parameters, temperature and crystal field. The theoretical results obtained in this study can enrich the magnetic properties of nanosystems and pave the way for researchers to experimentally study monolayer coronene-like nanostructure for future applications in nanotechnology.

The dielectric properties of a mixed Zethrene-inspired nanoscale system ($S_i^Z$-1, ${\sigma }_k^Z$-5/2) have been analyzed in detail using the Monte Carlo approach (MCa) in this study. First, the most stable configurations in different planes were investigated. Then, the influences of the physical factors, namely the coupling interaction factor, on the thermal behaviors of the polarization and the susceptibility of the studied nanostructure have been examined for nonzero temperatures and fixed external electric field values. It was found that the obtained transition temperature point relies weakly on the coupling interaction. Finally, the effects of the physical factors on the electric hysteresis cycles were discussed.

This study delves into the magnetic behavior of sulflower-like nanostructures, particularly focusing on compensation and blocking temperatures. Through the construction of a phase diagram detailing crystal and external magnetic fields (D/$J_{\sigma \sigma }$, H/$J_{\sigma \sigma })$, stable phases were identified, shedding light on how spin configurations evolve with variations in H/$J_{\sigma \sigma }$ and D/$J_{\sigma \sigma }$. The analysis of blocking temperature ($T_B$/$J_{\sigma \sigma })$ and compensation temperature ($T_{\mathrm{\text{comp}}}$/$J_{\sigma \sigma })$ relative to $J_{\sigma s}$/$J_{\sigma \sigma }$, $J_{ss}$/$J_{\sigma \sigma }$ and H/$J_{\sigma \sigma }$ reveals intriguing patterns. Additionally, an examination of hysteresis cycles uncovers dynamic behavior, characterized by multiple loops and magnetization plateaus. These findings open promising avenues for spintronic applications of sulflower-like nanostructures, offering valuable insights into their magnetic behavior and potential utility in future technologies. This involves the fabrication of high-density data storage devices, where its tunable magnetic characteristics may result in the development of effective data manipulation and storage components.

Magnetic properties and hysteresis of a mixed spins (1, 2) hexagonal Ising nanowire with core–shell structure in the presence of lattice anisotropy and external magnetic field are investigated by using Monte Carlo simulation based on the Metropolis algorithm. First, we analyze the ground state phase diagrams to discover all probable and stable configurations based on minimizing the system energy. The effects of the exchange couplings ($J_{\mathrm{\text{int}}}$, $J_s)$ and the single-ion anisotropies ($D_c$, $D_s)$ on the magnetic quantities of the system, namely, the total magnetization, the transition temperatures and the hysteresis curves. Several characteristic behaviors are found, such as the appearance and the compensation behavior, which is of crucial importance for technological applications such as thermo-optical recording. Additionally, under certain physical parameters, multiple cycle hysteresis loops, such as single and triple hysteresis loops, that exhibit different step effects and various forms, are observed.