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Spin-polarized current, spin-transfer torque and spin Hall effect in presence of an electromagnetic non-minimal coupling
Authors:
Rodrigo Turcati,
Carlos Andres Bonilla Quintero,
José Abdalla Helayël-Neto,
Enrique Arias
Abstract:
In this contribution, we start off from a fully relativistic description of a single electron non-minimally coupled to an external electromagnetic field. Making direct use of the field equation, instead of canonically deriving from the Lagrangian density, the relativistic total angular momentum is attained, where the effect of the relativistic torque due to the external sources is also taken into…
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In this contribution, we start off from a fully relativistic description of a single electron non-minimally coupled to an external electromagnetic field. Making direct use of the field equation, instead of canonically deriving from the Lagrangian density, the relativistic total angular momentum is attained, where the effect of the relativistic torque due to the external sources is also taken into account. Both the spin density and the orbital angular momentum tensors are identified in the relativistic-covariant approach. Furthermore, the symmetric and gauge invariant energy-momentum tensor is derived as well. In addition, to inspect the non-relativistic regime, a perturbative expansion of the field equation up to the leading order in $\left(v/c\right)$ is carried out, where spin-orbit interaction terms naturally emerge in the non-relativistic Hamiltonian as a consequence of the non-minimal coupling. Features related to the spin currents, the spin-transfer torque and their dependence on both magnetic and electric external fields are then calculated and discussed. Considering that spin-orbit coupled systems are of particular interest in the study of spin Hall effect, a two-dimensional (planar) scenario of the system is contemplated, where the contributions to the Landau levels are re-assessed. As a consequence of the planar regime and the non-minimal coupling, a peculiar sort of fractionalization of the spin-up and -down components emerges with the different spin components localized in distinct positions.
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Submitted 21 February, 2020; v1 submitted 28 July, 2019;
originally announced July 2019.
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Could Geoneutrinos Interact With the Geomagnetic Field?
Authors:
C. A. B. Quintero,
J. A. Helayël Neto
Abstract:
In the present paper, we consider the possibility of interaction between geoneutrinos and the geomagnetic field, by adopting an approach based on the Dirac's equation with a non-minimal coupling that accounts for the magnetic interaction of the massive neutrinos. In our approach, we see that the magnetic interaction is controlled by a dimensionless parameter, $f\simeq 10^{-1}$, and we estimate the…
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In the present paper, we consider the possibility of interaction between geoneutrinos and the geomagnetic field, by adopting an approach based on the Dirac's equation with a non-minimal coupling that accounts for the magnetic interaction of the massive neutrinos. In our approach, we see that the magnetic interaction is controlled by a dimensionless parameter, $f\simeq 10^{-1}$, and we estimate the mean value of this interaction to be of the order of $10^{-14}\ MeV^{2}$.
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Submitted 14 August, 2015;
originally announced August 2015.
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The gravitational wave signal of the short rise fling of galactic run away pulsars
Authors:
Herman J. Mosquera Cuesta,
Carlos A. Bonilla Quintero
Abstract:
Determination of pulsar parallaxes and proper motions addresses fundamental astrophysical open issues. Here, the ATNF Catalog is scrutinized searching for pulsar distances and proper motions. For a sample of 212 run away pulsars (RAPs), which currently run across the Galaxy at very high speed and undergo large displacements, some gravitational-wave (GW) signals produced by such present accelerat…
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Determination of pulsar parallaxes and proper motions addresses fundamental astrophysical open issues. Here, the ATNF Catalog is scrutinized searching for pulsar distances and proper motions. For a sample of 212 run away pulsars (RAPs), which currently run across the Galaxy at very high speed and undergo large displacements, some gravitational-wave (GW) signals produced by such present accelerations appear to be detectable after calibration against the Advanced LIGO (LIGO II). Motivated by this insight, we address the issue of the pulsar kick at birth. We show that during the short rise fling each run away pulsar (RAP) generates a GW signal with characteristic amplitude and frequency that makes it detectable by current GW interferometers. For a realistic analysis, an efficiency parameter is introduced to quantify the expenditure of the rise fling kinetic energy, which is estimated from the linear momentum conservation law applied to the supernova explosion that kicks out the pulsar. The remaining energy is supposed to be used to make the star to spin. Thus, a comparison with the spin of ATNF pulsars having velocity in the interval 400-500 km s$^{-1}$ is performed. The resulting difference suggests that other mechanisms should dissipate part of that energy to produce the observed pulsar spin periods. Meanwhile, the kick phenomenon may also occur in globular and open star clusters at the formation or disruption of very short period compact binary systems wherein abrupt velocity and acceleration similar to those given to RAPs during the short rise fling can be imparted to each orbital partner. Thus pulsar astrometry from micro- to nano-arsec scales might be of much help. In case of a supernova, the RAP GW signal could be a benchmark for the GW signal from the core collapse.
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Submitted 17 October, 2008; v1 submitted 20 November, 2007;
originally announced November 2007.
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Hubble diagram of gamma-ray bursts: Robust evidence for a Chaplygin gas expansion-driven universe with phase transition at $z \simeq 3$
Authors:
Herman J. Mosquera Cuesta,
Habib Dumet M.,
Rodrigo Turcati,
Carlos A. Bonilla Quintero,
Cristina Furlanetto,
Jefferson Morais
Abstract:
The Hubble diagram (HD) of Gamma-Ray Bursts (GRBs) having properly estimated redshifts is compared with the predicted one for the Chaplygin gas (CG), a dark energy candidate. The CG cosmology and that of Friedmann and $Λ$-CDM models are studied and confronted to the GRBs observations. The model-to-sample $χ^2$ statistical analysis indicates the CG model as the best fit. The present GRBs HD plot…
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The Hubble diagram (HD) of Gamma-Ray Bursts (GRBs) having properly estimated redshifts is compared with the predicted one for the Chaplygin gas (CG), a dark energy candidate. The CG cosmology and that of Friedmann and $Λ$-CDM models are studied and confronted to the GRBs observations. The model-to-sample $χ^2$ statistical analysis indicates the CG model as the best fit. The present GRBs HD plot exhibits a marked trend: as one goes back in time, it gets much closer to the predict HD for a Friedmann universe. This clear trend conclusively demonstrates that a transition from decelerate to accelerate expansion did take place. However, contrarily to claims based on supernovae type Ia, the transition redshift lies somewhere between $\sim 2.5 < z \simeq 3.5$ rather than at $z \sim 0.5-1$. All of these striking features of the GRBs HD constitute the most robust demonstration that the Chaplygin gas can in fact be the universe's driving dark energy field.
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Submitted 26 October, 2006;
originally announced October 2006.
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Hubble diagram of gamma-ray bursts and prevalence of energy conditions in Friedmann-Lemaître-Robertson-Walker Cosmology
Authors:
Herman J. Mosquera Cuesta,
Carlos A. Bonilla Quintero,
M. Habib Dumet,
Cristina Furlanetto,
Jefferson Morais,
Rodrigo Turcati
Abstract:
In this {\sl Letter} we construct the Hubble diagram (HD) for the standard Friedmann-Lemaître-Robertson-Walker (FLRW) cosmological model after enforcing it with the general relativistic energy conditions, heeding to investigate whether it still stands on as the leading scenario for cosmology in face of the distance modulus-redshift relation of a sample of GRBs that had their redshifts properly e…
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In this {\sl Letter} we construct the Hubble diagram (HD) for the standard Friedmann-Lemaître-Robertson-Walker (FLRW) cosmological model after enforcing it with the general relativistic energy conditions, heeding to investigate whether it still stands on as the leading scenario for cosmology in face of the distance modulus-redshift relation of a sample of GRBs that had their redshifts properly estimated and corrected upon applying on the data analysis the {\sl Ghirlanda relation} (Ghirlanda et al. 2004) and the recently discovered {\sl Firmani et al. relation} (Firmani et al. 2006a). Our $χ^2$ analysis support the view that FLRW plus the strong energy condition (SEC) is what better fits the GRB data. But this is not the whole story, since for a cosmological constant $Λ\neq 0$ the FLRW+SEC analysis with undefined $p=p(ρ)$ suggests that $Λ$ is not constant anyhow, because it does not follows the $p= ωρ$ HD, with $ω=-1$. Thenceforth, one concludes that either the cosmological constant does not exist at all, and consequently one is left with the FLRW+SEC which fits properly the GRBs HD and there is no late-time acceleration, or it does exist but should be time-varying. This all is contrary to current views based on SNIa observations that advogate for an actual constant $Λ$ and an accelerating universe. In connection to the results above, this last argumentation would imply that either there is something wrong with the SNIa interpretation regarding cosmic late-time acceleration (Middleditch 2006) or we will have to move away from general relativity. We would better to think that general relativity is still the most correct theory of gravity.
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Submitted 9 September, 2006;
originally announced September 2006.