Complexity, Forced and/or Self-Organized Criticality, and Topological Phase Transitions in Space Plasmas

Author(s):  
Tom Chang ◽  
Sunny W. Y. Tam ◽  
Cheng-Chin Wu ◽  
Giuseppe Consolini
2001 ◽  
Vol 8 (3) ◽  
pp. 175-180 ◽  
Author(s):  
T. Chang

Abstract. We consider the phenomena of intermittent turbulence in magnetized space plasmas from the point of view of topological phase transitions involving the merging and interactions of anisotropic coherent structures. The stochastic behaviour of these coherent plasma structures can undergo complex changes as the dynamic system evolves, similar to those commonly observed in (first and second order) equilibrium phase transitions. When conditions are favourable, such topological entities can evolve into a state of forced and/or self-organized criticality (FSOC). As an example, we apply these ideas to the understanding of the origin of the commonly observed broadband power-law low frequency electric field spectral densities and the characteristic filamentary current structures in the auroral zone. The broadband turbulence can provide efficient resonant energization of the ionospheric oxygen ions.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Adeel Y. Abid ◽  
Yuanwei Sun ◽  
Xu Hou ◽  
Congbing Tan ◽  
Xiangli Zhong ◽  
...  

AbstractNontrivial topological structures offer a rich playground in condensed matters and promise alternative device configurations for post-Moore electronics. While recently a number of polar topologies have been discovered in confined ferroelectric PbTiO3 within artificially engineered PbTiO3/SrTiO3 superlattices, little attention was paid to possible topological polar structures in SrTiO3. Here we successfully create previously unrealized polar antivortices within the SrTiO3 of PbTiO3/SrTiO3 superlattices, accomplished by carefully engineering their thicknesses guided by phase-field simulation. Field- and thermal-induced Kosterlitz–Thouless-like topological phase transitions have also been demonstrated, and it was discovered that the driving force for antivortex formation is electrostatic instead of elastic. This work completes an important missing link in polar topologies, expands the reaches of topological structures, and offers insight into searching and manipulating polar textures.


2020 ◽  
Vol 101 (24) ◽  
Author(s):  
Mohsen Hafez-Torbati ◽  
Jun-Hui Zheng ◽  
Bernhard Irsigler ◽  
Walter Hofstetter

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