If the Exciton has an effective "orbit" like the Earth-moon system, where does the angular momentum come from? And does that mean that Excitons are impossible in a direct bandgap material? Really loving these btw - as a noob with zero condensed matter physics knowledge, its great to have these "condensed" videos of whole areas of the subject haha.
sorry for the confusion. the analogy wasnt meant to be a direct one. since electrons (and holes) are quantum mechanical, a better analogy would have been of the hydrogen atom, where the lowest energy electron (s-state) has 0 angular momentum. so, direct bandgap excitons are fine, and actually this is what is proposed to happen in WTe2!
@@XenosumPhysics what does the angular momentum have to do with the material being direct or indirect gap? 0 (s) and 1 (p) angular momentum excitons can exist in both direct and indirect gap materials. Angular momentum and crystal's momentum (wavevector) are different concepts. The relative motion of the electron-hole pair is linked to the fine structure of the exciton (1s, 2s or 2p, etc excitons) while the centre-of-mass motion (how the exciton moves as a whole quasiparticle) is linked to the wavevector and the so called "exciton dispersion". Thanks for the nice video btw.
I used to play a game called VRChat. There I met this guy who worked in algorithm development for a company that contracts for the us government. Super cool guy and you would never think he's in the line of work he's in. Just seemed like a normal guy. Very fascinating to see different sides of people. We interact in social circles, and some people have disparate interests. Our interests aren't necessarily under our control, and its fascinating to realize that many people have this depth to them that you may never realize. Like an ant hill with tunnels that don't connect to every other part of the ant hill. Maybe it's not our place to know every side of the people we meet. I think it's good to appreciate the chances we get to connect with people, these gems of people that come along only a few times in a million.
I'm a physics undergrad, and I'm researching stuff about exitons with my proffesor. I was curious what was on RU-vid about, as I've only really learned enough to do the research and not anything extra. I burst out laughing when I saw this video (In a good way). You know, something about an anime Vtuber describing physics to me. I'm litteraly a weeb, physics major, who is researching exitons and I found this video, lol. I will check out more of your stuff.
Hi Xenny! PhD student in theoretical solid state physics here (electron structure theory), working on monolayer transition metal dichalcogenides. I can't get over the fact that there are only 6 videos on the channel, it's been such a treasure trove. I joined the Discord server, but can't find any word from you in the past year or so. Anyway, if you have time for that and would like to create videos together, please, do hit me up!
I appreciate your effort even if I may not have the grasp or appreciation for the subject that you and others in the discord do. Thank you for helping me learn and understand new concepts
Thank you for your nice description. Its really interesting for me. Please could give more basic explanation on berry curvature dipole moment and its importance.
Very very thank you for your kind and easy explanation! I could understand what is excitonic insulator thanks to this video. But I have one question about the video.
@@박정재-q1e good question, sorry the e-h drift picture isn't great for understanding, since you also have to take into account the effective mass of the carriers. electrons are in the conduction band, and holes are in the valence band, so theres a relative minus sign between their effective masses, and their current contributions ends up cancelling out in the equations. i probably should have just drawn them going in the same direction and explained that more thoroughly lol
Confirmation Today's androidic direct brain communication overlayering.... Was about Q~computering consiones of elec Tri city , and was about upside down pyramid string struckture ~ similar to the drawing of navigation, only as movment micro ? Of more evolution then peseption funktion education.
