Research Article
Magnetic Properties of One-dimensional Helical Spin System with Isotropic Spin Exchanges Under the Effect of DM and KSEA
Issue:
Volume 15, Issue 2, April 2026
Pages:
13-23
Received:
28 January 2026
Accepted:
12 February 2026
Published:
5 March 2026
Abstract: In the present work, we report on a theoretical investigation of the magnetoelectric parameters of the helical Heisenberg multiferroic spin chain model. The spin-wave approximation in the bosonization process is used to evaluate the energy spectrum of the quadratic form of the model as that of regular quantum gases. The quantized form of the model is conveniently treated using the canonical ensemble in terms of the free energy developed by the use of Landau theory. Following the Fermi-Dirac statistics of quantum gases, the joint effect of Dzyaloshinskii -Mriya (DM) and Kaplan-Shekhtman-Entin-Wohlman-Aharony (KSEA) interactions on the magnetoelectric properties of the helical multiferroic spin structure controlled by a static electric field in the y-direction and a magnetic field in the z-direction is quantified. The magnetization, susceptibility, and electric polarization are used as measurable parameters. The work convincingly establishes that the juxtaposition of KSEA interactions to DM interactions is worthy since, on the one hand, it amplifies the magnetic property of the system, and on the other hand makes it possible to control the phase transition dynamics induced in such materials by the symmetric inversion due to the DM interactions. At low temperature, the measurable parameters are closely related to ferroelectricity and ferromagnetism in multiferroic materials, where all effects favor the symmetrization mechanism and hence magnetoelectric properties. These properties are critical in spintronics and information storage control.
Abstract: In the present work, we report on a theoretical investigation of the magnetoelectric parameters of the helical Heisenberg multiferroic spin chain model. The spin-wave approximation in the bosonization process is used to evaluate the energy spectrum of the quadratic form of the model as that of regular quantum gases. The quantized form of the model ...
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Research Article
Influence of Jovian Planetary Motion on Sunspot Cycles
Fred John Cadieu*
Issue:
Volume 15, Issue 2, April 2026
Pages:
24-29
Received:
13 February 2026
Accepted:
28 February 2026
Published:
12 March 2026
Abstract: Sunspots are observable phenomena that emerge on the Sun’s surface, typically appearing in groups during intervals when the toroidal magnetic field of the Sun is heightened. These occurrences are not solely determined by the magnetic field’s strength; there is also a stochastic, or noise-related, component that influences sunspot manifestation during these elevated periods. This paper demonstrates that the periods of increased toroidal magnetic field are driven by the collective movement of the Jovian planets, which alters the location of the solar system’s center of mass relative to the Sun’s center. This dynamic motion introduces a cycle that is very close to 11 years in length. When both polarities of the Sun’s magnetic field are considered, this results in an overall 22-year magnetic cycle. For these effects to be effective the Sun’s dynamo must extend into the near surface layers. Sunspots emerge over both the northern and southern hemispheres of the Sun, following the typical butterfly pattern that is characteristic of sunspot distribution. While the collective motion of the Jovian planets drives the cyclical maxima in the Sun’s toroidal magnetic field, it is identified as a necessary-but not solely sufficient-factor for the development of sunspots. Based on the influence of the Jovian planets, it is predicted that the maximum for solar cycle 25 will occur between November and December 2024. Furthermore, solar cycle 26 is expected to reach its maximum around January 2037.
Abstract: Sunspots are observable phenomena that emerge on the Sun’s surface, typically appearing in groups during intervals when the toroidal magnetic field of the Sun is heightened. These occurrences are not solely determined by the magnetic field’s strength; there is also a stochastic, or noise-related, component that influences sunspot manifestation duri...
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Research Article
The Scalar-matter Direct Coupling and Attraction of
Brans-Dicke Gravity to General Relativity
Issue:
Volume 15, Issue 2, April 2026
Pages:
30-35
Received:
7 November 2025
Accepted:
24 November 2025
Published:
16 March 2026
DOI:
10.11648/j.ajmp.20261502.13
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Abstract: The original Brans-Dicke scalar-tensor gravity is believed to be attracted towards General Relativity with evolution of the Universe. In the presence of explicit scalar-matter direct coupling in the Brans-Dicke gravity, however, the attractor mechanism must be reconsidered. In this paper, the master equation found by Damour and Nordtvedt is rederived. It is shown that such a generalized master equation could modify the attraction to General Relativity and the scalar-matter direct coupling may accelerate or retard it. In original Brans-Dicke scalar-tensor gravity, the agent of the attraction to General Relativity is the gravitational coupling strength. However, in the presence of the scalar-matter direct coupling, the coupling function which characterizes the coupling of scalar field to matter, makes another potential associated with coupling and it produces a new coupling parameter in the existence of the scalar-matter direct coupling, the master equation which describes the evolution of scalar field, comes to have the force term of right hand side an additional term characterizing the scalar-matter coupling, i.e. the coupling parameter is lying in parallel with the strength parameter. Therefore, the attraction mechanism represented by the strength parameter alone comes to be modified by adding the new coupling parameter. The paper considered, in detail, the friction-dominated approximation which is a case of a negligible curvature of the scalar-curvature coupling potential. Then, depending on the sign of a new coupling parameter, the evolution of scalar field is shown to accelerate the attraction or to retard it. Consequently, the attraction towards General Relativity is modified on account of the scalar-matter direct coupling.
Abstract: The original Brans-Dicke scalar-tensor gravity is believed to be attracted towards General Relativity with evolution of the Universe. In the presence of explicit scalar-matter direct coupling in the Brans-Dicke gravity, however, the attractor mechanism must be reconsidered. In this paper, the master equation found by Damour and Nordtvedt is rederiv...
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