We explore a new type of domain wall structure in ultrathin films with perpendicular anisotropy, that is influenced by the Dzyaloshinskii-Moriya interaction due to the adjacent layers. This study is performed by numerical and analytical micromagnetics. We show that these walls can behave like Neel walls with very high stability, moving in stationary conditions at large velocities under large fields. We discuss the relevance of such walls, that we propose to call Dzyaloshinskii domain walls, for current-driven domain wall motion under the spin Hall effect.

https://iopscience.iop.org/article/10.1209/0295-5075/100/57002/pdf

Dynamics of Dzyaloshinskii domain walls in ultrathin magnetic films

A M was supported by the King Abdullah University of Science and Technology (KAUST) T J acknowledges support from the EU FET Open RIA Grant No 766566, the Ministry of Education of the Czech Republic Grant No LM2015087 and LNSM-LNSpin, and the Grant Agency of the Czech Republic Grant No 19-28375X J S acknowledges the Alexander von Humboldt Foundation, EU FET Open Grant No 766566, EU ERC Synergy Grant No 610115, and the Transregional Collaborative Research Center (SFB/TRR) 173 SPIN+X K G and P G acknowledge stimulating discussions with C O Avci and financial support by the Swiss National Science Foundation (Grants No 200021-153404 and No 200020-172775) and the European Commission under the Seventh Framework Program (spOt project, Grant No 318144) A T acknowledges support by the Agence Nationale de la Recherche, Project No ANR-17-CE24-0025 (TopSky) J Ž acknowledges the Grant Agency of the Czech Republic Grant No 19-18623Y and support from the Institute of Physics of the Czech Academy of Sciences and the Max Planck Society through the Max Planck Partner Group programme

/pdf/current-induced-spin-orbit-torques-in-ferromagnetic-and-3tdt106r3u.pdf

Current-induced spin-orbit torques in ferromagnetic and antiferromagnetic systems

Recently a Nahm transform has been discovered for magnetic bags, which are conjectured to arise in the large n limit of magnetic monopoles with charge n We interpret these ideas using string theory and present some partial proofs of this conjecture We then extend the notion of bags and their Nahm transform to higher gauge theories and arbitrary domains Bags in four dimensions conjecturally describe the large n limit of n self-dual strings We show that the corresponding Basu-Harvey equation is the large n limit of an equation describing n M2-branes, and that it has a natural interpretation in loop space We also formulate our Nahm equations using strong homotopy Lie algebras

Magnetic Domains

A single-cell transcriptomic atlas characterizes ageing tissues in the mouse

Spintronics is one of the emerging research fields in nanotechnology and has been growing very rapidly. Studies of spintronics were started after the discovery of giant magnetoresistance in 1988, which utilized spin-polarized electron transport across a non-magnetic metallic layer. Within 10 years, this discovery had been implemented into hard disk drives, the most common storage media, followed by recognition through the award of the Nobel Prize for Physics 19 years later. We have never experienced such fast development in any scientific field. Spintronics research is now moving into second-generation spin dynamics and beyond. In this review, we first examine the historical advances in spintronics together with the background physics, and then describe major device applications.

https://iopscience.iop.org/article/10.1088/0022-3727/47/19/193001/pdf

Future perspectives for spintronic devices

For many cancer types, incidence rises rapidly with age as an apparent power law, supporting the idea that cancer is caused by a gradual accumulation of genetic mutations. Similarly, the incidence of many infectious diseases strongly increases with age. Here, combining data from immunology and epidemiology, we show that many of these dramatic age-related increases in incidence can be modeled based on immune system decline, rather than mutation accumulation. In humans, the thymus atrophies from infancy, resulting in an exponential decline in T cell production with a half-life of ∼16 years, which we use as the basis for a minimal mathematical model of disease incidence. Our model outperforms the power law model with the same number of fitting parameters in describing cancer incidence data across a wide spectrum of different cancers, and provides excellent fits to infectious disease data. This framework provides mechanistic insight into cancer emergence, suggesting that age-related decline in T cell output is a major risk factor.

/pdf/thymic-involution-and-rising-disease-incidence-with-age-3rlojxvmsl.pdf

Thymic involution and rising disease incidence with age

We make the observation that M-brane models defined in terms of 3-algebras can be interpreted as higher gauge theories involving Lie 2-groups. Such gauge theories arise in particular in the description of non-abelian gerbes. This observation allows us to put M2- and M5-brane models on equal footing, at least as far as the gauge structure is concerned. Furthermore, it provides a useful framework for various generalizations; in particular, it leads to a fully supersymmetric generalization of a previously proposed set of tensor multiplet equations.

M-brane models from non-abelian gerbes

M-brane Models from Non-Abelian Gerbes

We analyze the gauge structure of a recently proposed superconformal field theory in six dimensions. We find that this structure amounts to a weak Courant-Dorfman algebra, which, in turn, can be interpreted as a strong homotopy Lie algebra. This suggests that the superconformal field theory is closely related to higher gauge theory, describing the parallel transport of extended objects. Indeed we find that, under certain restrictions, the field content and gauge transformations reduce to those of higher gauge theory. We also present a number of interesting examples of admissible gauge structures such as the structure Lie 2-algebra of an abelian gerbe, differential crossed modules, the 3-algebras of M2-brane models and string Lie 2-algebras.

Sam Palmer

Papers

Magnetic Domains

Thymic involution and rising disease incidence with age

M-brane models from non-abelian gerbes

M-brane Models from Non-Abelian Gerbes

Six-Dimensional (1,0) Superconformal Models and Higher Gauge Theory