scholarly journals Optimal configuration and symmetry breaking phenomena in the composite membrane problem with fractional Laplacian

2021 ◽  
Vol 274 ◽  
pp. 1165-1208
Author(s):  
María del Mar González ◽  
Ki-Ahm Lee ◽  
Taehun Lee
2020 ◽  
Vol 6 (23) ◽  
pp. eaaz8809 ◽  
Author(s):  
Libor Šmejkal ◽  
Rafael González-Hernández ◽  
T. Jungwirth ◽  
J. Sinova

Electrons, commonly moving along the applied electric field, acquire in certain magnets a dissipationless transverse velocity. This spontaneous Hall effect, found more than a century ago, has been understood in terms of the time-reversal symmetry breaking by the internal spin structure of a ferromagnetic, noncolinear antiferromagnetic, or skyrmionic form. Here, we identify previously overlooked robust Hall effect mechanism arising from collinear antiferromagnetism combined with nonmagnetic atoms at noncentrosymmetric positions. We predict a large magnitude of this crystal Hall effect in a room temperature collinear antiferromagnet RuO2 and catalog, based on symmetry rules, extensive families of material candidates. We show that the crystal Hall effect is accompanied by the possibility to control its sign by the crystal chirality. We illustrate that accounting for the full magnetization density distribution instead of the simplified spin structure sheds new light on symmetry breaking phenomena in magnets and opens an alternative avenue toward low-dissipation nanoelectronics.


2009 ◽  
Vol 18 (04) ◽  
pp. 1014-1021
Author(s):  
R. G. NAZMITDINOV ◽  
A. PUENTE

A brief description of excited and ground states in two-dimensional quantum dots and rotating nuclei is presented within a mean field approach and a random-phase approximation (RPA). We discuss the procedure to restore the rotational symmetry broken at the mean field, which can be extended for other symmetry breaking cases. We propose to consider a disappearance of collective excitations in the rotating frame as a manifestation of symmetry breaking phenomena of the rotating mean field. In particular, we demonstrate that the disappearance of a collective octupole mode in the rotating frame in 162 Yb gives rise to the nonaxial octupole deformation.


2019 ◽  
Vol 18 (5) ◽  
pp. 2679-2691
Author(s):  
Giovanni Cupini ◽  
◽  
Eugenio Vecchi ◽  

CrystEngComm ◽  
2015 ◽  
Vol 17 (24) ◽  
pp. 4421-4433 ◽  
Author(s):  
Guanghui An ◽  
Pengfei Yan ◽  
Jingwen Sun ◽  
Yuxin Li ◽  
Xu Yao ◽  
...  

Racemate-to-homochiral crystallization was highlighted for symmetry breaking phenomena by showing clear pictures of the mechanism and development history.


2017 ◽  
Vol 73 (5) ◽  
pp. 403-413
Author(s):  
Il Hwan Kim ◽  
Jong Ok Pak ◽  
Il Hun Kim ◽  
Song Won Kim ◽  
Lin Li

A new concept of the wavevector substar group is established which, in the study of translational symmetry breaking of a crystal, only considers the particular arms of the wavevector star taking part in the phase transition; this is in contrast with the traditional Landau theory which considers all of the arms of the wavevector star. It is shown that this new concept can be used effectively to investigate the interesting physical properties of crystals associated with translational symmetry breaking. It is shown that studies on complicated phase transitions related to reducible representations, such as those in perovskite KMnF3multiferroics and the high-temperature superconductor La2/3Mg1/2W1/2O3(La4Mg3W3O18), are much simplified by the new concept. The theory of the wavevector substar group and its representation is a powerful mathematical tool for the study of various symmetry-breaking phenomena in solid-state crystals.


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