scholarly journals Theoretical guidelines to create and tune electric skyrmion bubbles

2019 ◽  
Vol 5 (2) ◽  
pp. eaau7023 ◽  
Author(s):  
M. A. Pereira Gonçalves ◽  
Carlos Escorihuela-Sayalero ◽  
Pablo Garca-Fernández ◽  
Javier Junquera ◽  
Jorge Íñiguez

Researchers have long wondered whether ferroelectrics may present topological textures akin to magnetic skyrmions and chiral bubbles, the results being modest thus far. An electric equivalent of a typical magnetic skyrmion would rely on a counterpart of the Dzyaloshinskii-Moriya interaction and seems all but impossible; further, the exotic ferroelectric orders reported to date rely on specific composites and superlattices, limiting their generality and properties. Here, we propose an original approach to write topological textures in simple ferroelectrics in a customary manner. Our second-principles simulations of columnar nanodomains, in prototype material PbTiO3, show we can harness the Bloch-type structure of the domain wall to create objects with the usual skyrmion-defining features as well as unusual ones—including isotopological and topological transitions driven by external fields and temperature—and potentially very small sizes. Our results suggest countless possibilities for creating and manipulating such electric textures, effectively inaugurating the field of topological ferroelectrics.

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
S. Ghara ◽  
K. Geirhos ◽  
L. Kuerten ◽  
P. Lunkenheimer ◽  
V. Tsurkan ◽  
...  

AbstractAtomically sharp domain walls in ferroelectrics are considered as an ideal platform to realize easy-to-reconfigure nanoelectronic building blocks, created, manipulated and erased by external fields. However, conductive domain walls have been exclusively observed in oxides, where domain wall mobility and conductivity is largely influenced by stoichiometry and defects. Here, we report on giant conductivity of domain walls in the non-oxide ferroelectric GaV4S8. We observe conductive domain walls forming in zig-zagging structures, that are composed of head-to-head and tail-to-tail domain wall segments alternating on the nanoscale. Remarkably, both types of segments possess high conductivity, unimaginable in oxide ferroelectrics. These effectively 2D domain walls, dominating the 3D conductance, can be mobilized by magnetic fields, triggering abrupt conductance changes as large as eight orders of magnitude. These unique properties demonstrate that non-oxide ferroelectrics can be the source of novel phenomena beyond the realm of oxide electronics.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ruyi Chen ◽  
Qirui Cui ◽  
Liyang Liao ◽  
Yingmei Zhu ◽  
Ruiqi Zhang ◽  
...  

AbstractPerpendicularly magnetized synthetic antiferromagnets (SAF), possessing low net magnetization and high thermal stability as well as easy reading and writing characteristics, have been intensively explored to replace the ferromagnetic free layers of magnetic tunnel junctions as the kernel of spintronic devices. So far, utilizing spin-orbit torque (SOT) to realize deterministic switching of perpendicular SAF have been reported while a large external magnetic field is typically needed to break the symmetry, making it impractical for applications. Here, combining theoretic analysis and experimental results, we report that the effective modulation of Dzyaloshinskii-Moriya interaction by the interfacial crystallinity between ferromagnets and adjacent heavy metals plays an important role in domain wall configurations. By adjusting the domain wall configuration between Bloch type and Néel type, we successfully demonstrate the field-free SOT-induced magnetization switching in [Co/Pd]/Ru/[Co/Pd] SAF devices constructed with a simple wedged structure. Our work provides a practical route for utilization of perpendicularly SAF in SOT devices and paves the way for magnetic memory devices with high density, low stray field, and low power consumption.


2018 ◽  
Vol 4 (12) ◽  
pp. eaav0265 ◽  
Author(s):  
Tomohiro Koyama ◽  
Yoshinobu Nakatani ◽  
Jun’ichi Ieda ◽  
Daichi Chiba

We show that the electric field (EF) can control the domain wall (DW) velocity in a Pt/Co/Pd asymmetric structure. With the application of a gate voltage, a substantial change in DW velocity up to 50 m/s is observed, which is much greater than that observed in previous studies. Moreover, modulation of a DW velocity exceeding 100 m/s is demonstrated in this study. An EF-induced change in the interfacial Dzyaloshinskii-Moriya interaction (DMI) up to several percent is found to be the origin of the velocity modulation. The DMI-mediated velocity change shown here is a fundamentally different mechanism from that caused by EF-induced anisotropy modulation. Our results will pave the way for the electrical manipulation of spin structures and dynamics via DMI control, which can enhance the performance of spintronic devices.


2020 ◽  
Author(s):  
Woo-Seung Ham ◽  
Abdul-Muizz Pradipto ◽  
Kay Yakushiji ◽  
Kwangsu Kim ◽  
Sonny Rhim ◽  
...  

Abstract Dzyaloshinskii-Moriya interaction (DMI) is considered as one of the most important energy for specific chiral texture such as magnetic skyrmions. The key of generating DMI is absence of structural inversion symmetry and exchange energy with spin-orbit coupling. Therefore, a vast majority of researches about DMI is mainly limited to heavy metal/ferromagnet bilayer systems, only focusing on their interfaces. Here, we report that asymmetric band formation in an artificial superlattice arises from inversion symmetry breaking in stacking order of atomic layers, resulting in bulk DMI. Such bulk DMI is more than 300% larger than simple sum of interfacial contribution. Moreover, the asymmetric band is largely affected by strong spin-orbit coupling, showing crucial role of a heavy metal even in the non-interfacial origin of DMI. Such Rashba superlattices can be a new class of material design for spintronics applications.


2019 ◽  
Vol 122 (14) ◽  
Author(s):  
Kyoung-Whan Kim ◽  
Seo-Won Lee ◽  
Jung-Hwan Moon ◽  
Gyungchoon Go ◽  
Aurélien Manchon ◽  
...  

2020 ◽  
Vol 116 (22) ◽  
pp. 222406
Author(s):  
Kostiantyn V. Yershov ◽  
Volodymyr P. Kravchuk ◽  
Denis D. Sheka ◽  
Jeroen van den Brink ◽  
Avadh Saxena

2019 ◽  
Vol 100 (22) ◽  
Author(s):  
Dae-Yun Kim ◽  
Nam-Hui Kim ◽  
Yong-Keun Park ◽  
Min-Ho Park ◽  
Joo-Sung Kim ◽  
...  

Nanoscale ◽  
2019 ◽  
Vol 11 (42) ◽  
pp. 20102-20114 ◽  
Author(s):  
Vasileios D. Stavrou ◽  
Drosos Kourounis ◽  
Konstantinos Dimakopoulos ◽  
Ioannis Panagiotopoulos ◽  
Leonidas N. Gergidis

The magnetization reversal in magnetic FePt nanoelements having Reuleaux 3D geometry is studied using Finite Element micromagnetic simulations. Multiple skyrmions are formed for a range of external fields and magnetocrystalline anisotropy values.


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