arXiv subjects

Hamid Arian Zad

Publications and source records attributed to Hamid Arian Zad.

31 records · Page 2Linked to original sources

arXiv2020

Spin-1/2 Ising-Heisenberg Cairo pentagonal model in the presence of an external magnetic field: Effect of Landé g-factors

In the present paper, a study of the magnetic properties of a spin-1/2 Ising-Heisenberg Cairo pentagonal structure is presented. The model has been investigated in Ref. [34] in the absence of external magnetic field. Here, we consider the effects of an external tunable magnetic field. By using the transfer matrix approach, we investigate the magnetic ground-state phase transition, the low-temperature magnetization process, and how the magnetic field influences the various thermodynamic parameters such as entropy, internal energy and specific heat. It is shown that the model exhibits intermediate magnetization plateaux accompanied by a double-peak in the specific heat curve versus temperature. The position of each magnetization jump is in accordance with the merging and/or separation of the two peaks in the specific heat curve. Considering different g-factors for the nodal Ising spins and spin dimers also results in arising different intermediate plateaux and to remarkable alterations of the thermodynamic properties of the model.

cond-mat.stat-mech↗

arXiv2020

Quantum coherence, quantum Fisher information and teleportation in the Ising-Heisenberg spin chain model of a heterotrimetallic Fe-Mn-Cu coordination polymer with magnetic impurity

The effect of non-uniform magnetic fields on the Ising-Heisenberg chain of a heterotrimetallic coordination compound $\mathrm{Fe-Mn-Cu}$, modeling a magnetic impurity on one dimer is studied. This impurity is configured by imposing non-uniform magnetic fields on each sites of $j-$th interstitial ionic dimer $\mathrm{Mn}^{2+}-\mathrm{Cu}^{2+}$ of the chain model. The quantum coherence and pairwise entanglement between spin-1/2 magnetic $\mathrm{Mn}^{2+}-\mathrm{Cu}^{2+}$ ion dimers clearly depend on the site which the impurity is located. It is demonstrated that when the magnetic impurity is considered for one magnetic dimer, by altering Ising nodal exchange interaction and Heisenberg anisotropy parameter of the impurity dimer, the entanglement can be enhanced to the maximal value 1 at a special fixed magnetic field. Moreover, we find that the quantum Fisher information of the model with magnetic impurity behaves considerably different from the original model. Besides of the quantum resources like concurrence, we prove that the quantum Fisher information can be used as new quantum tool for estimating the quantum phase transition in the model under consideration. On the other hand, thermal teleportation can be significantly optimized by adjusting the magnetic impurity, and a strong increase in the average fidelity is observed. Finally, the magnetic impurity can be manipulated to locally control the thermal entanglement, coherence, quantum Fisher information and teleportation unlike the original model where it is done globally.

quant-ph↗

arXiv2020

Effect of annealing treatment on the structural, optical and magnetic properties of ZnSe thin films grown by spray pyrolysis

Many investigations and reviews show that II-VI compound semiconductor 1-D nanostructures have a great potential for the future electronic and optoelectronic applications. As an important II-VI semiconductor, ZnSe is one of the most significant materials with prominent applications in this issue. In the present work, we firstly provide a comprehensive investigation of the magnetic properties like magnetization and magnetic susceptibility of ZnSe nanostructures as a 1-D quantum many body. The magnetic study of this metal reveals a ferromagnetic-antifferomagnetic transition upon cooling. Magnetization shows a step-like behavior with pronounced plateaus in a specific magnetic field interval at low temperature. This subject has not been investigated in the previous works. In the experimental part, thin films of ZnSe are deposited on glass substrates (at two different substrate temperature) by the spray pyrolysis technique and annealed in vacuum at $400^\circ$C for 1 hour. Hereby, we investigate the morphology, structural and optical properties of ZnSe thin films using field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD) and UV-vis spectrophotometer measurements. XRD analysis reveal that annealed films grown on glass substrate at $400^\circ$C are polycrystalline in nature with cubic zincblene structure. By annealing, the grains size, the diameter and density of the particles increase. The UV-vis measurements display a red-shift of the absorption edge from the as-deposited to annealed ZnSe thin films as compared to its value for the ZnSe thin films. The band-gaps of the annealed samples are estimated about 2.71 eV, which are in consistence with the band gap of ZnSe thin films. The average transmittance of the annealed samples are over 80 $\%$ close to the infrared wavelength range.

physics.app-ph↗

arXiv2019

Magnetic and thermodynamic properties of the octanuclear nickel phosphonate-based cage

We report a detailed theoretical investigation into the influence of anisotropy on the magnetic and thermodynamic properties of an octanuclear nickel phosphonate cage with butterfly-shaped molecular geometry, namely $\mathrm{Ni}_8(μ_3-\mathrm{OH})_4(\mathrm{OMe})_2(\mathrm{O}_3\mathrm{PR}_1)_2 (\mathrm{O}_2\mathrm{C}^t\mathrm{Bu})_6 (\mathrm{HO}_2\mathrm{C}^t\mathrm{Bu})_8$. To validate our exact diagonalization approach, we firstly compare results with simulations and experiment in the isotropic case. Having established concurrence, we then introduce uniaxial single-ion anisotropy and Heisenberg exchange anisotropy between interacted nickel atoms. We then examine effects of both anisotropy parameters on the magnetization process, as well as on the specific heat of the model. We predict intermediate magnetization plateaus, including zero plateau, and magnetization jumps with magnetic ground-state phase transitions at low temperature $T=1$K. The magnetization plateaus are strongly dependent on both the levels of exchange anisotropy and single-ion anisotropy. Varying the former leads to change in width and magnetic position of all intermediate plateaus while they become wider upon increasing the latter. The specific heat of the model manifests a Schottky-type maximum at moderate temperature in the presence of weak magnetic fields, when the system is isotropic. The introducion of aniostropy results in substantial variations in the thermal behavior of the specific heat. Indeed, by tuning anisotropy parameters the Schottky peak convert to a double-peak temperature dependence that coincided with the magnetization jumps. We call for these theoretical predictions to be verified experimentally at low temperature.

cond-mat.stat-mech↗

arXiv2019

Magnetic properties of an antiferromagnetic spin-1/2 XYZ model in the presence of different magnetic fields: finite-size effects of inhomogeneity property

Magnetic and thermodynamic properties of the anisotropic XYZ spin-1/2 finite chain under both homogeneous and inhomogeneous magnetic fields are theoretically studied at low temperature. Using exact diagonalization method (ED), we study the magnetization, magnetic susceptibility and specific heat of the model characterized in terms of the finite correlation length in the presence of three different magnetic fields including longitudinal, transverse and transverse staggered magnetic fields. The magnetization, susceptibility and the specific heat of the model are investigated under two conditions separately: I) when the model is putted in the presence of homogeneous magnetic fields; II) when finite inhomogeneities are considered for all applied magnetic fields in the Hamiltonian. We show that for the finite-size XYZ chains at low temperature, the evident magnetization plateaus gradually convert to their counterpart quasi-plateaus when the transverse magnetic field increases. Moreover, the influence of the transverse and staggered transverse magnetic fields, and their corresponding inhomogeneities on the magnetization process, magnetic susceptibility, and specific heat are reported in detail. Our exact results illustrate that by altering the inhomogeneity parameters, magnetization plateaus gradually convert to their counterpart quasi-plateaus. The specific heat manifests Schottky-type maximum, double-peak and triple-peak, as well as, transformation between them by varying considered inhomogeneity parameters in the Hamiltonian.

cond-mat.stat-mech↗

arXiv2019

Electrocaloric effect in the two spin-1/2 XXZ Heisenberg edge-shared tetrahedra and spin-1/2 XXZ Heisenberg octahedron with Dzyaloshinskii-Moriya interaction

In the present paper, we consider two species of small spin clusters known as; two spin-1/2 Heisenberg edge-shared tetrahedra and spin-1/2 Heisenberg octahedron with the corresponding Dzyaloshinskii-Moriya terms in a longitudinal magnetic field, then we examine magnetization process and electric polarization of the models as functions of magnetic and electric fields at Low temperature using exact numerical diagonalization. Our exact results are in a good agreement with recent analysis carried out by J. Strečka and K. Kar{\v l}ova \cite{str18b,str17a}. It is demonstrated that the polarization behavior coincides the magnetization curves (including sequential intermediate plateaus), also it reflects the respective stepwise changes of ground-state phase transitions. We find that the polarization has significant effects on the magnetic field dependencies of the magnetization. Furthermore, we investigate other isothermal strategies such as cooling rate, magnetocaloric effect (MCE), as well as, electrocaloric effect(ECE) for both models. Since, new electrocaloric materials with high performance is of great interest and importance in condensed matter physics, here, we report on the ECE of the both aforedescribed spin-1/2 Heisenberg small clusters. We conclude that two spin-1/2 Heisenberg edge-shared tetrahedra is a material with significant reversible temperature change capability under an external electric field compared with the spin-1/2 Heisenberg octahedron, and can be used for cooling/heating process.

cond-mat.str-el↗

arXiv2019

The specific heat and magnetic properties of a spin-1/2 ladder including butterfly-shaped unit blocks

The specific heat, structural characterization, and magnetic property studies of a new spin ladder with the geometry of butterfly-shaped configuration are reported. The model introduced here is an infinite spin ladder-type including spin-1/2 particle for which unit blocks consist of two butterflies connected together through their bodies (Body-Body bridges). Localized spins on the wings of butterflies have XXZ Heisenberg interaction with two extra spin-1/2 particles assumed in the center of each cage (unit block), while they have pure Ising-type interaction with those spins that are localized on the bodies. Hence, there are six interstitial spins and four nodal spins (Body-Body interaction) per block. To obtain the partition function of this model, we use the transfer matrix approach, then we examine the magnetization process, as well as, the specific heat of the model. Interestingly, we see a wide plateau at $\frac{5}{6}$ of the saturation magnetization that is strongly dependent on the magnetic field and anisotropy variations. Moreover, some unexpected phenomena are observed in the low-temperature limit, such as anomalous triple-peak in the specific heat function which gradually turns to a double-peak upon increasing the magnetic field and/or anisotropic Heisenberg coupling, due to the ferromagnetic phase predomination.

cond-mat.stat-mech↗

arXiv2018

Entanglement in a fermionic spin chain containing a single mobile boson under decoherence

The concurrence between first and the last sites of a fermionic spin chain containing a single boson is rigorously investigated at finite low temperature in the vicinity of a weak homogeneous magnetic field. We consider the boson as a mobile spin-1 particle through the chain and study concurrence without/under decoherence and express some interesting phase flip and bit flip reactions of the pairwise entanglement between first and the last half-spins in the chain. Our investigations show that the concurrence between two considered half-spins has different behavior for various positions of the single boson along the chain. Indeed, we realize that the single boson mobility has an essential role to probe the pairwise entanglement intensity between two spins located at the opposite ends of a fermionic chain. Interestingly, the entanglement remains alive for higher temperatures when the boson is the nearest neighbor of the first fermion. When the boson is at the middle of chain, it is demonstrated that the threshold temperature (at which the concurrence vanishes) versus decoherence rate can be considered as a threshold temperature boundary. These results pave the way to set and interpret the numerical and analytical expressions for utilizing quantum information in realistic scenarios such as quantum state transmission, quantum communication science and quantum information processing, where the both fermion-fermion and fermion-boson correlations should be taken in to account.

cond-mat.stat-mech↗

arXiv2018

Magnetocaloric effect in the distorted Ising-Heisenberg double sawtooth spin ladders

The entropy and cooling rate of the both antiferromagnetic spin-1/2 double sawtooth IsingHeisenberg model and mixed-spin (1,1/2) double sawtooth Ising-Heisenberg model on the distorted ladders are rigorously investigated under an adiabatic demagnetization process using the quantum transfer-matrix technique. The models include the XXZ interaction between the interstitial Heisenberg dimers, the Ising coupling between nearest-neighbor spins of the legs and rungs, and additional cyclic four-spin exchange (ring exchange) in the square plaquette of each block. Close to field-induced quantum phase transitions, we compare both models together in the ability of cooling/heating near the quantum critical points. However, we observe a large magnetocaloric effect for both models, the mixed-spin double sawtooth ladder shows much more magneticaloric efficiency than the spin-1/2 double sawtooth ladder. During an adiabatic demagnetization process it can be seen a temperature dropping in the vicinity of the zero-temperature quantum phase transitions. Various fixed values of the Isotropic and anisotropic parameters explicitly alter the quality of the magnetocaloric effect. This properties suggest double sawtooth Ising-Heisenberg ladders as promising alternative refrigerant materials for low-temperature magnetic refrigeration.

cond-mat.stat-mech↗

arXiv2018

Thermal entanglement in the mixed-spin Ising-Heisenberg double sawtooth frustrated ladder

The entanglement between spin-1/2 interstitial Heisenberg dimers in the mixed spin-(1,1/2) Ising-XXZ double sawtooth ladder is investigated at low temperature. Here, we consider a cyclic four-spin exchange interaction in square plaquette of each block, and investigate the effects of this amazing interaction on the bipartite entanglement between spin-1/2 interstitial dimers. Interestingly, we observe a remarkable difference in concurrence behavior with respect to the cyclic four-spin exchange interaction and magnetic field. Also, the critical points at which the concurrence vanishes are changed versus alteration of the anisotropic parameter of the interstitial Heisenberg dimers.

cond-mat.stat-mech↗

arXiv2018

Classical correlation and quantum entanglement in the mixed-spin Ising-XY model with Dzyaloshinskii-Moriya interaction

In the present work, initially a mixed-three-spin (1/2,1,1/2) cell of a mixed-N-spin chain with Ising-XY model is introduced, for which pair spins (1,1/2) have Ising-type interaction and pair spins (1/2,1/2) have both XY-type and Dzyaloshinskii-Moriya(DM) interactions together. An external homogeneous magnetic field B is considered for the system in thermal equilibrium. Integer-spins have a single-ion anisotropy property with coefficient ζ. Then, we investigate the quantum entanglement between half-spins (1/2,1/2), by means of the concurrence. Classical correlation(CC) for this pair of spins is investigated as well as the concurrence and some interesting the temperature, the magnetic field and the DM interaction properties are expressed. Moreover, single-ion anisotropy effects on the correlation between half-spins is verified. According to the verifications based on the communication channels category by D. Rossini, V. Giovannetti and R. Fazio 63, we theoretically consider such tripartite spin model as an ideal quantum channel, then calculate its information transmission rate and express some differences in behaviour between this suggested model and introduced simple models in the previous works(chains without spin integer and DM interaction) from information transferring protocol point of view.

cond-mat.stat-mech↗

arXiv2018

Phase transitions and magnetization of the mixed-spin Ising-Heisenberg double sawtooth frustrated ladder

The mixed spin-(1,1/2) Ising-Heisenberg double sawtooth ladder containing mixture of both spin-1 and spin-1/2 nodal atoms, and the spin-1/2 interstitial dimers is approximately solved by the transfer-matrix method. Here, we study in detail the ground-state phase diagrams, also influences of the bilinear exchange coupling on the rungs and cyclic four-spin exchange interaction in square plaquette of each block on the magnetization and magnetic susceptibility of the suggested ladder at low temperature. Such a double sawtooth ladder may be found in a Shastry-Sutherland Lattice-type. In spite of odd and even blocks spin ordering are different from each other, but due to the commutation relation between all different block Hamiltonians, phase diagrams, magnetization behavior and thermodynamic properties of the model are the same for odd and even blocks. We show that at low temperature, both exchange couplings can change the quality and quantity of the magnetization plateaus versus the magnetic field changes. Specially, we find a new magnetization plateau M/Ms = 5/6 for this model. Besides, we examine the magnetic susceptibility and specific heat of the model in detail. It is proven that behaviors of the magnetization and the magnetic susceptibility coincide at low temperature. The specific heat displays diverse temperature dependencies, which include a Schottky-type peak at a special temperature interval. We observe that with increase of the bilinear exchange coupling on the rungs, second peak temperature dependence grows.

cond-mat.stat-mech↗

arXiv2017

Phase transitions and thermal entanglement of the distorted Ising-Heisenberg spin chain: topology of multiple-spin exchange interactions in spin ladders

We consider a symmetric spin-1/2 Ising-XXZ double sawtooth spin ladder obtained from distorting a spin chain, with the XXZ interaction between the interstitial Heisenberg dimers (which are connected to the spins based on the legs via an Ising-type interaction), the Ising coupling between nearest-neighbor spins of the legs and rungs spins, respectively, and additional cyclic four-spin exchange (ring exchange) in square plaquette of each block. The presented analysis supplemented by results of the exact solution of the model with infinite periodic boundary implies a rich ground state phase diagram. As well as the quantum phase transitions, the characteristics of some of the thermodynamic parameters such as heat capacity, magnetization and magnetic susceptibility are investigated. We here prove that among the considered thermodynamic and thermal parameters, solely the heat capacity is sensitive versus the changes of the cyclic four-spin exchange interaction. By using the heat capacity function, we obtain a singularity relation between the cyclic four-spin exchange interaction and the exchange coupling between pair spins on each rung of the spin ladder. All thermal and thermodynamic quantities under consideration should investigate by regarding those points which satisfy the singularity relation. The thermal entanglement within the Heisenberg spin dimers is investigated by using the concurrence, which is calculated from a relevant reduced density operator in the thermodynamic limit.

cond-mat.stat-mech↗