scholarly journals Quantum theory of the nonlinear Hall effect

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Z. Z. Du ◽  
C. M. Wang ◽  
Hai-Peng Sun ◽  
Hai-Zhou Lu ◽  
X. C. Xie

AbstractThe nonlinear Hall effect is an unconventional response, in which a voltage can be driven by two perpendicular currents in the Hall-bar measurement. Unprecedented in the family of the Hall effects, it can survive time-reversal symmetry but is sensitive to the breaking of discrete and crystal symmetries. It is a quantum transport phenomenon that has deep connection with the Berry curvature. However, a full quantum description is still absent. Here we construct a quantum theory of the nonlinear Hall effect by using the diagrammatic technique. Quite different from nonlinear optics, nearly all the diagrams account for the disorder effects, which play decisive role in the electronic transport. After including the disorder contributions in terms of the Feynman diagrams, the total nonlinear Hall conductivity is enhanced but its sign remains unchanged for the 2D tilted Dirac model, compared to the one with only the Berry curvature contribution. We discuss the symmetry of the nonlinear conductivity tensor and predict a pure disorder-induced nonlinear Hall effect for point groups C3, C3h, C3v, D3h, D3 in 2D, and T, Td, C3h, D3h in 3D. This work will be helpful for explorations of the topological physics beyond the linear regime.

2022 ◽  
Vol 5 (1) ◽  
Author(s):  
Hiroyuki Moriya ◽  
Akira Musha ◽  
Satoshi Haku ◽  
Kazuya Ando

AbstractThe physics of the anomalous and spin Hall effects is one of the most intriguing aspects of condensed matter physics. An important finding from a large collection of experimental and theoretical results is the universal scaling of the anomalous or spin Hall conductivity with the electric conductivity. This scaling has been successfully described by the intrinsic Berry curvature and extrinsic scattering mechanisms for metallic systems, revealing the topological nature of these effects. In contrast, the underlying physics in the opposite limit, the disordered insulating regime, is still unclear. In particular, it remains a major challenge, both experimentally and theoretically, to explore the spin Hall effect in the insulating regime. Here, we report the observation of the crossover between the metallic and insulating regimes of the spin Hall effect. The result demonstrates a direct correspondence between the spin and anomalous Hall effects, which will advance the fundamental understanding of spin transport.


2021 ◽  
Author(s):  
Hiroyuki Moriya ◽  
Akira Musha ◽  
Satoshi Haku ◽  
Kazuya Ando

Abstract The physics of the anomalous and spin Hall effects is one of the most intriguing aspects of condensed matter physics. An important finding from a large collection of experimental and theoretical results is the universal scaling of the anomalous or spin Hall conductivity with the electric conductivity. This scaling has been successfully described by the intrinsic Berry curvature and extrinsic scattering mechanisms for metallic systems, revealing the topological nature of these effects. In contrast, the underlying physics in the opposite limit, the disordered insulating regime, is still unclear. In particular, it remains a major challenge to explore the spin Hall effect in the insulating regime. Here, we report the observation of the crossover between the metallic and insulating regimes of the spin Hall effect. The result demonstrates an important correspondence between the spin and anomalous Hall effects, which provides essential information for the fundamental understanding of spin transport.


1970 ◽  
pp. 38-45
Author(s):  
May Abu Jaber

Violence against women (VAW) continues to exist as a pervasive, structural,systematic, and institutionalized violation of women’s basic human rights (UNDivision of Advancement for Women, 2006). It cuts across the boundaries of age, race, class, education, and religion which affect women of all ages and all backgrounds in every corner of the world. Such violence is used to control and subjugate women by instilling a sense of insecurity that keeps them “bound to the home, economically exploited and socially suppressed” (Mathu, 2008, p. 65). It is estimated that one out of every five women worldwide will be abused during her lifetime with rates reaching up to 70 percent in some countries (WHO, 2005). Whether this abuse is perpetrated by the state and its agents, by family members, or even by strangers, VAW is closely related to the regulation of sexuality in a gender specific (patriarchal) manner. This regulation is, on the one hand, maintained through the implementation of strict cultural, communal, and religious norms, and on the other hand, through particular legal measures that sustain these norms. Therefore, religious institutions, the media, the family/tribe, cultural networks, and the legal system continually disciplinewomen’s sexuality and punish those women (and in some instances men) who have transgressed or allegedly contravened the social boundaries of ‘appropriateness’ as delineated by each society. Such women/men may include lesbians/gays, women who appear ‘too masculine’ or men who appear ‘too feminine,’ women who try to exercise their rights freely or men who do not assert their rights as ‘real men’ should, women/men who have been sexually assaulted or raped, and women/men who challenge male/older male authority.


2017 ◽  
Vol 5 (1) ◽  
pp. 498
Author(s):  
Maria Stănescu

The article is about the role of the family in the education and formation of children and, especially, in the life and development of autistic children. It describes the problems their family is facing and the need for counseling to parents with autistic children. The reaction to finding the diagnosis of autism varies from one family to another and may encounter a large variety: from disbelief, anger, guilt, helplessness, devastation, surprise, or even rejection of the child, to understanding and relief when finally the parents have an explanation for their child behaviors. Early intervention is important in psychological sustaining of the parent, as parent involvement in the recovery of the child with autism has a determinant role in his development and in ensuring a high quality of life of the child and the life of the hole family. The response to a child's autism diagnosis varies from one family to another. The family goes through a variety of disbelief, anger, guilt, helplessness, devastation, surprise, or even rejection of the child, to understanding and relief. Early intervention is very important in the psychological support of the parent. Because any change disturbs the family equilibrium. A diagnosis of autism changes not only the life of the diagnosed child, but also the life of family members. All the resources are focused on the need of the child. Although each parent is different, after diagnosing the child with autism, all parents are overwhelmed by confusion, shock and denial. Parents' feelings can be influenced by how their children's situation affects different aspects of life - it has an impact on service, on social life and all their personal life. If we look at the family as a system and when a disturbing factor appears, all parts of the system are affected. The involvement of parents in the recovery of the child with autism has a decisive role in its development and in ensuring a high quality of child's life and family life.


Author(s):  
Eleticia Isabel Pinargote Macías ◽  
Francisco Ashley Gavilanes Vaca ◽  
Víctor Hugo Cedeño Gavilánez

The resilience of parents can play a decisive role as a resource that favors the inclusion and development of students with disabilities, representing a decisive contribution in school-family co-responsibility. This work showed a conceptual analysis related to resilience from a family dimension and especially the role played by parents. The research was carried out in the context of the Technical University of Manabí, a representative sample of students with disabilities and their families was selected, two instruments were applied to obtain the data: Family Functioning Scale [1] and the Mother Resilience Scale [2]. The attention to the young person with a disability was analyzed, and it is particularized in the related to the family of these. The results are shown in tables that allow the final results to be identified.


Author(s):  
Frank S. Levin

Surfing the Quantum World bridges the gap between in-depth textbooks and typical popular science books on quantum ideas and phenomena. Among its significant features is the description of a host of mind-bending phenomena, such as a quantum object being in two places at once or a certain minus sign being the most consequential in the universe. Much of its first part is historical, starting with the ancient Greeks and their concepts of light, and ending with the creation of quantum mechanics. The second part begins by applying quantum mechanics and its probability nature to a pedagogical system, the one-dimensional box, an analog of which is a musical-instrument string. This is followed by a gentle introduction to the fundamental principles of quantum theory, whose core concepts and symbolic representations are the foundation for most of the subsequent chapters. For instance, it is shown how quantum theory explains the properties of the hydrogen atom and, via quantum spin and Pauli’s Exclusion Principle, how it accounts for the structure of the periodic table. White dwarf and neutron stars are seen to be gigantic quantum objects, while the maximum height of mountains is shown to have a quantum basis. Among the many other topics considered are a variety of interference phenomena, those that display the wave properties of particles like electrons and photons, and even of large molecules. The book concludes with a wide-ranging discussion of interpretational and philosophic issues, introduced in Chapters 14 by entanglement and 15 by Schrödinger’s cat.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Fei Wang ◽  
Xuepeng Wang ◽  
Yi-Fan Zhao ◽  
Di Xiao ◽  
Ling-Jie Zhou ◽  
...  

AbstractThe Berry phase picture provides important insights into the electronic properties of condensed matter systems. The intrinsic anomalous Hall (AH) effect can be understood as the consequence of non-zero Berry curvature in momentum space. Here, we fabricate TI/magnetic TI heterostructures and find that the sign of the AH effect in the magnetic TI layer can be changed from being positive to negative with increasing the thickness of the top TI layer. Our first-principles calculations show that the built-in electric fields at the TI/magnetic TI interface influence the band structure of the magnetic TI layer, and thus lead to a reconstruction of the Berry curvature in the heterostructure samples. Based on the interface-induced AH effect with a negative sign in TI/V-doped TI bilayer structures, we create an artificial “topological Hall effect”-like feature in the Hall trace of the V-doped TI/TI/Cr-doped TI sandwich heterostructures. Our study provides a new route to create the Berry curvature change in magnetic topological materials that may lead to potential technological applications.


2021 ◽  
pp. 2006301
Author(s):  
Satya N. Guin ◽  
Qiunan Xu ◽  
Nitesh Kumar ◽  
Hsiang‐Hsi Kung ◽  
Sydney Dufresne ◽  
...  

Author(s):  
Elena de Andrés-Jiménez ◽  
Rosa Mª Limiñana-Gras ◽  
Encarna Fernández-Ros

The aim of this study is to determine the existence of a characteristic personality profile of family carers of people with dementia. The correct knowledge and use of psychological variables which affect the carer, helps to promote appropriate actions to mitigate the impact of care and improve the carer’s quality of life and likewise the one of the person cared for. The study population consists of 69 family carers of people with dementia, members of various associations and care centers. The results allow us to identify a characteristic personality profile for these carers and it reveals a specific psychological working in this sample, although we cannot directly relate it with the tasks of caring for people with this disease, this profile gives us very relevant information to pay more attention to the needs of this group. Moreover, the analysis of personality styles depends on the sex of the family carer, showing, once again, that the woman is in a situation of most vulnerability.


2021 ◽  
Vol 4 (1) ◽  
Author(s):  
X. R. Wang

AbstractSpin current is a very important tensor quantity in spintronics. However, the well-known spin-Hall effect (SHE) can only generate a few of its components whose propagating and polarization directions are perpendicular with each other and to an applied charge current. It is highly desirable in applications to generate spin currents whose polarization can be in any possible direction. Here anomalous SHE and inverse spin-Hall effect (ISHE) in magnetic systems are predicted. Spin currents, whose polarisation and propagation are collinear or orthogonal with each other and along or perpendicular to the charge current, can be generated, depending on whether the applied charge current is along or perpendicular to the order parameter. In anomalous ISHEs, charge currents proportional to the order parameter can be along or perpendicular to the propagating or polarization directions of the spin current.


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