요새 논문을 보면 magnetic 관련 연구에서 skyrmion이라는 단어를 볼 수 있다.
skyrmion이란 뭘까?
A skyrmion can be described as a swirling quasi-particle, a knot of twisting field lines, or a subatomic hurricane. They're also one of the most difficult physics concepts for humans to understand
Skyrmions are named for British nuclear physicist Tony Skyrme, who first proposed their existence in 1961. His idea was to model subatomic entities like protons and neutrons using convoluted twists in the quantum field that all particles possess
The idea was eventually superseded by a theory known as quantum chromo-dynamics, which was more successful at modeling subatomic particles. But skyrmions have been revived by researchers working on magnetic fields, which can also be coaxed into forming vortex-like swirls.
In a magnetic skyrmion, the knotted magnetic field lines wrap around one another like key rings hooking into other key rings, creating a nanometer-scale shape that is impossible to pull apart without breaking the rings. In a magnetic field, the formation can drift from one spot to another, with the skyrmion making itself anew from lines at any given location.
Because skyrmions are so small and stable, physicists are interested in controlling these particle-like entities for use in futuristic computers and electronic memory storage
Since it takes relatively little power to maintain and electronically access data stored in magnetic skyrmions, engineers think these particles could make for very efficient memory-storage devices. An emerging field called skyrmionics is now dedicated to creating such next-generation appliances.
Magnetic skyrmions are swirling topological configurations, which are mostly induced by chiral interactions between atomic spins in non-centrosymmetric magnetic bulks or in thin films with broken inversion symmetry. They hold promise as information carriers in future ultra-dense, low-power memory and logic devices owing to the nanocale size and extremely low spin-polarized currents needed to move them
as the continual miniaturization of CMOS technology, the increased power dissipation owing to the inevitable leakage currents caused by the quantum effect [2] has become one of the most critical issues, leading to the failure of this famous empirical principle (Moore's law)
spintronics has been extensively expected to be one of the most potential candidates in the next post-Moore’s law era, especially for the emerging topological particle-like spin configurations known as magnetic skyrmions for alternative information carriers
the standby energy consumption and heat generation during the processing and transportation of information can be efficiently reduced thanks to the nonvolatility, which is the common superiority of spintronic devices in comparison with CMOS
The origin of skyrmions can be briefly explained as a consequence of competition between the ferromagnetic exchange coupling, the Dzyaloshinskii-Moriya interaction (DMI, bulk or interfacial) and other energies in magnetic systems lacking inversion symmetry
DMI is a critical parameter which stabilizes skyrmions and impacts the skyrmion size
The basic idea of creating skyrmions is to overcome the potential barrier so as to induce a topological transition of the magnetic textures. So far, various concepts, e.g. heat, magnetic field, voltage and electrical current, have been proposed to realize skyrmion creation at the custom-defined position of a device
Hall effect가 뭔지 찾아봐야겠다.
일단 spintronic에서 필요한 개념(?) 인거 같다. 정확한것은 차차 알아가자.