A Nonlinear Theoretical Model of Magnetization and Magnetostriction for Ferromagnetic Materials under Applied Stress and Magnetic Fields

2020 ◽  
Vol 37 (8) ◽  
pp. 087502
Author(s):  
Pengpeng Shi
Keyword(s):  
Theoretical Model ◽  
Magnetic Fields ◽  
Applied Stress ◽  
Ferromagnetic Materials

scholarly journals Bilinear magnetoresistance in HgTe topological insulator: opposite signs at opposite surfaces demonstrated by gate control

2021 ◽  
Author(s):  
Yu Fu ◽  
Jing Li ◽  
Jules Papin ◽  
Paul Noel ◽  
Maxen Cosset-Chéneau ◽  
...  
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Magnetic Fields ◽  
Figure Of Merit ◽  
Electrical Response ◽  
Surface States ◽  
Spin Orbit ◽  
Electric And Magnetic Fields ◽  
Gate Control ◽  
Quantitative Account

Abstract Spin-orbit effects appearing in topological insulators (TI) and at Rashba interfaces are currently revolutionizing how we can manipulate spins and have led to several newly discovered effects, from spin-charge interconversion and spin-orbit torques to novel magnetoresistance phenomena. In particular, a puzzling magnetoresistance has been evidenced, bilinear in electric and magnetic fields. Here, we report the observation of bilinear magnetoresistance (BMR) in strained HgTe, a prototypical TI. We show that both the amplitude and sign of this BMR can be tuned by controling, with an electric gate, the relative proportions of the opposite contributions of opposite surfaces. At magnetic fields of 1 T, the magnetoresistance is of the order of 1 \% and has a larger figure of merit than previously measured TIs. We propose a theoretical model giving a quantitative account of our experimental data. This phenomenon, unique to TI, offer novel opportunities to tune the electrical response of surface states for spintronics.

scholarly journals Conceptual Fields and Magnetic Field: a theoretical model for epistemological classification of tasks in magnetostatics

2021 ◽  
Vol 26 (3) ◽  
pp. 82
Author(s):  
Glauco Cohen Ferreira Pantoja
Keyword(s):  
Magnetic Field ◽  
Higher Education ◽  
Theoretical Model ◽  
Magnetic Fields ◽  
Conceptual Structure ◽  
Magnetic Interactions ◽  
Physics Teaching ◽  
Secondary Classes ◽  
Epistemological Complexity

This work presents a theoretical model for epistemological classification of tasks in magnetostatics aimed at High School and Higher Education. The approach is based on the theory of conceptual fields and includes classification in terms of thought operations necessary to solve the tasks and in these situations’ parameters. Four primary classes of situations are proposed, namely, description of magnetic interactions, analogic symbolization of magnetic fields, non-analogic symbolization of magnetic fields and calculation of magnetic fields. These classes cannot be reduced one to another, however they can occur simultaneously in the same task. Each one was subdivided in secondary classes of situations based on parameters they can assume and ordered by epistemological complexity. As contributions for physics teaching research this work offers a theoretical-methodological model for analyzing students’ progression in the conceptual field of magnetostatics, a conceptual structure for building situations based on predicative and operational competences for understanding the concept of magnetic field, and a practical example of epistemological classification of situations that can be adapted for other areas of Science like Quantum Mechanics, for example.

Quantum Reflection of Ultracold Atoms in Magnetic Traps

1999 ◽  
Vol 54 (3-4) ◽  
pp. 167-170
Author(s):  
Rui-Hua Xie ◽  
Paul Brumer
Keyword(s):  
Theoretical Model ◽  
Magnetic Fields ◽  
Transition Region ◽  
Ultracold Atoms ◽  
Neutral Atoms ◽  
Magnetic Traps ◽  
Potential Barriers ◽  
Resonant Transition ◽  
Quantum Reflection ◽  
Spatially Inhomogeneous

Ultracold neutral atoms can be trapped in spatially inhomogeneous magnetic fields. In this paper, we present a theoretical model and demonstrate by using Landau-Zener tool that if the magnetic resonant transition region is very narrow, "potential barriers" appear and quantum reflection of such ultracold atoms can be observed in this region.

scholarly journals The B Fields in OB Stars (BOB) Survey

2014 ◽  
Vol 9 (S307) ◽  
pp. 342-347 ◽  
Author(s):  
T. Morel ◽  
N. Castro ◽  
L. Fossati ◽  
S. Hubrig ◽  
N. Langer ◽  
...  
Keyword(s):  
Theoretical Model ◽  
Lower Bound ◽  
Magnetic Fields ◽  
Field Strength ◽  
Massive Stars ◽  
Occurrence Rate ◽  
Early Type ◽  
Ob Stars ◽  
Early Type Stars ◽  
Field Formation

AbstractThe B fields in OB stars (BOB) survey is an ESO large programme collecting spectropolarimetric observations for a large number of early-type stars in order to study the occurrence rate, properties, and ultimately the origin of magnetic fields in massive stars. As of July 2014, a total of 98 objects were observed over 20 nights with FORS2 and HARPSpol. Our preliminary results indicate that the fraction of magnetic OB stars with an organised, detectable field is low. This conclusion, now independently reached by two different surveys, has profound implications for any theoretical model attempting to explain the field formation in these objects. We discuss in this contribution some important issues addressed by our observations (e.g., the lower bound of the field strength) and the discovery of some remarkable objects.

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