scholarly journals Skyrmion crystals in centrosymmetric itinerant magnets without horizontal mirror plane

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ryota Yambe ◽  
Satoru Hayami

AbstractWe theoretically investigate a new stabilization mechanism of a skyrmion crystal (SkX) in centrosymmetric itinerant magnets with magnetic anisotropy. By considering a trigonal crystal system without the horizontal mirror plane, we derive an effective spin model with an anisotropic Ruderman–Kittel–Kasuya–Yosida (RKKY) interaction for a multi-band periodic Anderson model. We find that the anisotropic RKKY interaction gives rise to two distinct SkXs with different skyrmion numbers of one and two depending on a magnetic field. We also clarify that a phase arising from the multiple-Q spin density waves becomes a control parameter for a field-induced topological phase transition between the SkXs. The mechanism will be useful not only for understanding the SkXs, such as that in Gd$$_2$$ 2 PdSi$$_3$$ 3 , but also for exploring further skyrmion-hosting materials in trigonal itinerant magnets.

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Milad Jangjan ◽  
Mir Vahid Hosseini

AbstractWe theoretically report the finding of a new kind of topological phase transition between a normal insulator and a topological metal state where the closing-reopening of bandgap is accompanied by passing the Fermi level through an additional band. The resulting nontrivial topological metal phase is characterized by stable zero-energy localized edge states that exist within the full gapless bulk states. Such states living on a quasi-one-dimensional system with three sublattices per unit cell are protected by hidden inversion symmetry. While other required symmetries such as chiral, particle-hole, or full inversion symmetry are absent in the system.


2021 ◽  
Vol 126 (1) ◽  
Author(s):  
Niraj Aryal ◽  
Xilian Jin ◽  
Q. Li ◽  
A. M. Tsvelik ◽  
Weiguo Yin

2002 ◽  
Vol 299 (5-6) ◽  
pp. 622-627 ◽  
Author(s):  
Shigeru Ishimoto ◽  
Toshio Kobayashi ◽  
Kimio Morimoto ◽  
Izumi Nomura ◽  
Akira Ozawa ◽  
...  

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