scholarly journals Unconventional Thermal and Magnetic-Field-Driven Changes of a Bipartite Entanglement of a Mixed Spin-(1/2,S) Heisenberg Dimer with an Uniaxial Single-Ion Anisotropy

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3096
Author(s):  
Hana Vargová ◽  
Jozef Strečka
Keyword(s):  
Magnetic Field ◽  
Thermal Stability ◽  
Threshold Temperature ◽  
Model Parameters ◽  
Thermal Entanglement ◽  
Bipartite Entanglement ◽  
Mixed Spin ◽  
Discontinuous Phase ◽  
Antiferromagnetic Spin ◽  
Degree Of Entanglement

The concept of negativity is adapted in order to explore the quantum and thermal entanglement of the mixed spin-(1/2,S) Heisenberg dimers in presence of an external magnetic field. The mutual interplay between the spin size S, XXZ exchange and uniaxial single-ion anisotropy is thoroughly examined with a goal to tune the degree and thermal stability of the pairwise entanglement. It turns out that the antiferromagnetic spin-(1/2,S) Heisenberg dimers exhibit higher degree of entanglement and higher threshold temperature in comparison with their ferromagnetic counterparts when assuming the same set of model parameters. The increasing spin magnitude S accompanied with an easy-plane uniaxial single-ion anisotropy can enhance not only the thermal stability but simultaneously the degree of entanglement. It is additionally shown that the further enhancement of a bipartite entanglement can be achieved in the mixed spin-(1/2,S) Heisenberg dimers, involving half-odd-integer spins S. Under this condition the thermal negativity saturates at low-enough temperatures in its maximal value regardless of the magnitude of half-odd-integer spin S. The magnetic field induces consecutive discontinuous phase transitions in the mixed spin-(1/2,S) Heisenberg dimers with S>1, which are manifested in a surprising oscillating magnetic-field dependence of the negativity observed at low enough temperature.

Thermal entanglement in a mixed spin Heisenberg XXX chain with DM interaction

2021 ◽  
pp. 2150021
Author(s):  
Nizar Ahami ◽  
Morad El Baz
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Thermal Entanglement ◽  
Bipartite Entanglement ◽  
Dm Interaction ◽  
One Dimensional ◽  
Mixed Spin ◽  
Xxx Model ◽  
Moriya Interaction ◽  
Heisenberg Xxx Model

We consider a one-dimensional, mixed spin Heisenberg XXX model with an homogeneous external magnetic field and Dzyaloshinskii–Moriya interaction. Alternating spin-[Formula: see text] and spin-1 particles are forming the chain. The effect of the different parameters of the system on the bipartite thermal entanglement is studied. The type of chain used (mixed) and the size of the chain ([Formula: see text]) allow to study three types of bipartite entanglement, the qubit–qubit, qubit–qutrit and qutrit–qutrit thermal entanglement.

scholarly journals Thermal Entanglement and Critical Behavior of Magnetic Properties on a Triangulated Kagomé Lattice

10.14311/1344 ◽  
2011 ◽  
Vol 51 (2) ◽  
Author(s):  
N. Ananikian ◽  
L. Ananikyan ◽  
L. Chakhmakhchyan ◽  
A. Kocharian
Keyword(s):  
Magnetic Field ◽  
Heisenberg Model ◽  
Quantum Phase Transitions ◽  
Exchange Interactions ◽  
Effective Field ◽  
Threshold Temperature ◽  
Kagome Lattice ◽  
Thermal Entanglement ◽  
Kagomé Lattice ◽  
Bogoliubov Inequality

The equilibrium magnetic and entanglement properties in a spin-1/2 Ising-Heisenberg model on a triangulated Kagomé lattice are analyzed by means of the effective field for the Gibbs-Bogoliubov inequality. The calculation is reduced to decoupled individual (clusters) trimers due to the separable character of the Ising-type exchange interactions between the Heisenberg trimers. The concurrence in terms of the three qubit isotropic Heisenberg model in the effective Ising field in the absence of a magnetic field is non-zero. The magnetic and entanglement properties exhibit common (plateau, peak) features driven by a magnetic field and (antiferromagnetic) exchange interaction. The (quantum) entangled and non-entangled phases can be exploited as a useful tool for signalling the quantum phase transitions and crossovers at finite temperatures. The critical temperature of order-disorder coincides with the threshold temperature of thermal entanglement.

Thermal entanglement in a mixed-spin Heisenberg XXZ model under a nonuniform external magnetic field

2009 ◽  
Vol 52 (12) ◽  
pp. 1919-1924 ◽  
Author(s):  
Fei Wang ◽  
HongHui Jia ◽  
HaiLiang Zhang ◽  
XueAo Zhang ◽  
ShengLi Chang
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Thermal Entanglement ◽  
Xxz Model ◽  
Mixed Spin ◽  
Heisenberg Xxz Model

scholarly journals Magnetic-Field-Orientation Dependent Thermal Entanglement of a Spin-1 Heisenberg Dimer: The Case Study of Dinuclear Nickel Complex with an Uniaxial Single-Ion Anisotropy

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3420
Author(s):  
Azadeh Ghannadan ◽  
Jozef Strečka
Keyword(s):  
Magnetic Field ◽  
Nickel Complex ◽  
Energy Gap ◽  
Ground States ◽  
Quantum Spin ◽  
Thermal Entanglement ◽  
Bipartite Entanglement ◽  
Field Orientation ◽  
Magnetic Field Orientation ◽  
The Magnetic Field

The bipartite entanglement in pure and mixed states of a quantum spin-1 Heisenberg dimer with exchange and uniaxial single-ion anisotropies is quantified through the negativity in a presence of the external magnetic field. At zero temperature the negativity shows a marked stepwise dependence on a magnetic field with two abrupt jumps and plateaus, which can be attributed to the quantum antiferromagnetic and quantum ferrimagnetic ground states. The magnetic-field-driven phase transition between the quantum antiferromagnetic and quantum ferrimagnetic ground states manifests itself at nonzero temperatures by a local minimum of the negativity, which is followed by a peculiar field-induced rise of the negativity observable in a range of moderately strong magnetic fields. The rising temperature generally smears out abrupt jumps and plateaus of the negativity, which cannot be distinguished in the relevant dependencies above a certain temperature. It is shown that the thermal entanglement is most persistent against rising temperature at the magnetic field, for which an energy gap between a ground state and a first excited state is highest. Besides, temperature variations of the negativity of the spin-1 Heisenberg dimer with an easy-axis single-ion anisotropy may exhibit a singular point-kink, at which the negativity has discontinuity in its first derivative. The homodinuclear nickel complex [Ni2(Medpt)2(μ-ox)(H2O)2](ClO4)2·2H2O provides a suitable experimental platform of the antiferromagnetic spin-1 Heisenberg dimer, which allowed us to estimate a strength of the bipartite entanglement between two exchange-coupled Ni2+ magnetic ions on the grounds of the interaction constants reported previously from the fitting procedure of the magnetization data. It is verified that the negativity of this dinuclear compound is highly magnetic-field-orientation dependent due to presence of a relatively strong uniaxial single-ion anisotropy.

Unveiling the thermal entanglement in a mixed-spin XXZ model with Dzyaloshinskii–Moriya interaction under a homogeneous magnetic field

2015 ◽  
Vol 29 (03) ◽  
pp. 1550005 ◽  
Author(s):  
Cheng-Cheng Liu ◽  
Shuai Xu ◽  
Juan He ◽  
Liu Ye
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Homogeneous Magnetic Field ◽  
Coupling Constant ◽  
Thermal Entanglement ◽  
Xxz Model ◽  
Dm Interaction ◽  
Mixed Spin ◽  
External Magnetic Field Strength ◽  
Moriya Interaction

We analytically investigate the thermal entanglement of three-mixed-spin (1/2, 1, 1/2) XXZ model with the DM interaction under an external magnetic field B. Two different cases are considered: one subsystem (1/2, 1/2) consists of two spin-1/2 fermions and the other subsystem (1/2, 1) contains a spin-1/2 fermion and a spin-1 boson. It is shown that the DM interaction parameter D, the external magnetic field strength B and coupling constant J have different effects on Fermi and mixed Fermi–Bose systems. All of the factors mentioned above can be utilized to control entanglement switch of any two particles in mixed spins model.

scholarly journals THERMAL ENTANGLEMENT IN A TWO-QUTRIT SYSTEM WITH NONLINEAR COUPLING UNDER NONUNIFORM EXTERNAL MAGNETIC FIELD

2008 ◽  
Vol 06 (04) ◽  
pp. 867-884 ◽  
Author(s):  
IMAN SARGOLZAHI ◽  
SAYYED YAHYA MIRAFZALI ◽  
MOHSEN SARBISHAEI
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Lower Bounds ◽  
Threshold Temperature ◽  
Nonlinear Coupling ◽  
Dense Coding ◽  
Thermal Entanglement ◽  
Finite Dimensional ◽  
Coding Capacity ◽  
The Magnetic Field

We study the thermal entanglement of a 2-qutrit spin chain with nonlinear coupling in the presence of nonuniform magnetic field. Thermal entanglement of an arbitrary (finite-dimensional) m-partite system vanishes at some finite threshold temperature Ts. We investigate the dependence of Ts on the system's parameters, i.e. the nonlinear coupling and the magnetic field, for this 2-qutrit system. In addition, we compare two lower bounds of I-concurrence for this system and also study its dense coding capacity as a function of system's parameters.

scholarly journals Preparation and Thermal Conductivity of Epoxy Resin/Graphene-Fe3O4 Composites

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2013
Author(s):  
Zhong Wu ◽  
Jingyun Chen ◽  
Qifeng Li ◽  
Da-Hai Xia ◽  
Yida Deng ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Thermal Conductivity ◽  
Thermal Stability ◽  
Epoxy Resin ◽  
Thermomechanical Properties ◽  
Packaging Materials ◽  
Mass Ratio ◽  
Degree Of Orientation ◽  
Ep Matrix ◽  
Electrical Insulation Properties

By modifying the bonding of graphene (GR) and Fe3O4, a stable structure of GR-Fe3O4, namely magnetic GR, was obtained. Under the induction of a magnetic field, it can be orientated in an epoxy resin (EP) matrix, thus preparing EP/GR-Fe3O4 composites. The effects of the content of GR and the degree of orientation on the thermal conductivity of the composites were investigated, and the most suitable Fe3O4 load on GR was obtained. When the mass ratio of GR and Fe3O4 was 2:1, the thermal conductivity could be increased by 54.8% compared with that of pure EP. Meanwhile, EP/GR-Fe3O4 composites had a better thermal stability, dynamic thermomechanical properties, and excellent electrical insulation properties, which can meet the requirements of electronic packaging materials.

scholarly journals Sequential modelling of the Earth’s core magnetic field

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Guillaume Ropp ◽  
Vincent Lesur ◽  
Julien Baerenzung ◽  
Matthias Holschneider
Keyword(s):  
Magnetic Field ◽  
Prior Information ◽  
Spatial Scales ◽  
Model Parameters ◽  
International Geomagnetic Reference Field ◽  
The Earth ◽  
Temporal And Spatial ◽  
Different Sources ◽  
Original Approach ◽  
Modelling Approach

Abstract We describe a new, original approach to the modelling of the Earth’s magnetic field. The overall objective of this study is to reliably render fast variations of the core field and its secular variation. This method combines a sequential modelling approach, a Kalman filter, and a correlation-based modelling step. Sources that most significantly contribute to the field measured at the surface of the Earth are modelled. Their separation is based on strong prior information on their spatial and temporal behaviours. We obtain a time series of model distributions which display behaviours similar to those of recent models based on more classic approaches, particularly at large temporal and spatial scales. Interesting new features and periodicities are visible in our models at smaller time and spatial scales. An important aspect of our method is to yield reliable error bars for all model parameters. These errors, however, are only as reliable as the description of the different sources and the prior information used are realistic. Finally, we used a slightly different version of our method to produce candidate models for the thirteenth edition of the International Geomagnetic Reference Field.

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