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03/06/2017 HYU News > Academics Important News


Spin-Orbit Interaction and Holographic Theory

Professor Sin Sang-jin (Department of Physics)


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Physics is an indispensable domain to invest in as it generates fundamental knowledge for technological infrastructure and future advancements. Accentuating the importance of the field, Professor Sin Sang-jin (Department of Physics) puts strenuous effort into enlightening unresolved physical phenomena. In his paper "Character Of Matter in Holography: Spin-orbit Interaction," Sin elaborated the relationship between holographic theory and spin-orbit interaction using graphite to decode the enigma.
String theory and spin-orbit interaction

Physical phenomena relating to the notion of gravity can be explained through Einstein’s general theory of relativity at a macroscopic level. However, narrowing down the matter and studying at a microscopic level, the so-called quantum gravity theory must enter the picture. Among other quantum gravity theories, the prime candidate that is attracting much interest is string theory, which states that the smallest particle of matter is not a point molecule but a vibrating string, which cannot be decomposed further. String theory focuses on holographic duality (also known as gauge/gravity duality) as a novel method of approaching and connecting a range of subjects, including quantum gravity.
The movement and interaction between the electronic system are not holistically mastered by physicists, rendering the strongly correlated electronic system cryptic. By employing the holographic theory, which states that the description volume of space could be encoded on a lower-dimensional boundary to the region, can explain not only electron-to-electron interaction but also lattice-electron interaction. Of the interactions of electrons, spin-orbit interaction is what Sin sheds light on.
Sin describes the complexity of the relationships between several theories.

Spin-orbit interaction is a type of particle interation which causes shifts in an electron’s energy level caused by the electromagnetic interaction between the electron’s spin and the magnetic field. This field is generated by the electron’s orbit around the nucleus. The big question here was to figure out how to fit this interaction into the holographic theory, which connects to another phenomenon called anomalous hall effect. This effect is the traversing of electric current in the magnetic field perpendicular to the current, with no electromagnetic force applied. What is peculiar is the aberration; perpendicular traversing would happen only when electromagnetic force is applied.
To find the answer to this puzzle, Sin applied the magnetization curve of graphite to the spin-orbit interaction, which fitted suitably. This was because the magnetization curve of graphite was well-depicted by the strong interaction between electrons. Uncountable layers of graphene make up graphite, corresponding to the strongly interacting temperature and density.
The ultimate goal of Sin’s research is to construct a solid theory of physics for novel materials. In the process, string theory and holographic theory are incorporated to the core concept. “This particular research paper at hand merely managed to link the notion with spin-orbit interaction, which could be compared to just one tree out of an entire forest. I aim to theorize the strongly-correlated electronic system,” noted Sin. “Many say there aren't any phenomena which can’t be explained with theories formed 100 years ago. This isn't true in my view. Physicists today still cannot explain matters with the strongly correlated electronic system. There is no end to physics and its exploration,” added Sin.
Sin asserts that physics is the base of all phenomena.

Jeon Chae-yun
Photos by Choi Min-ju
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