| 0:00:02 | hello |
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| 0:00:03 | my name is trained freedom one i'm looking at the university of cambridge and today |
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| 0:00:07 | i want to tell you what is interesting about our electronic structure studies on the |
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| 0:00:12 | fisher wrote into silicon two |
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| 0:00:14 | it sounds like a rather export a combination of elements but it is actually a |
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| 0:00:19 | member of a very broad family of materials including the are make taxable conductors and |
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| 0:00:24 | have experiment material |
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| 0:00:27 | now if we don't want to know the properties of a metal we need to |
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| 0:00:30 | know it's crystal structure and we usually to use this from x ray diffraction measurements |
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| 0:00:35 | the other important bit is the electronic structure and here quantum oscillation measurements are very |
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| 0:00:40 | powerful pro |
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| 0:00:42 | so now we have you met investigated with use "'em" road young to silicon two |
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| 0:00:47 | which is have that mturk and all |
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| 0:00:50 | crystal structure we know it's lattice parameters from x ray diffraction but there's one thing |
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| 0:00:55 | one missing power meter |
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| 0:00:58 | namely position of the silicon atoms within the unit so it's that this that position |
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| 0:01:03 | of this so they can atoms |
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| 0:01:05 | so we've done |
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| 0:01:07 | high resolution single crystal structure refinement to find the silicon position and we perform numerical |
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| 0:01:13 | that israel excitation calculations to find the minimal energy |
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| 0:01:18 | corresponding a silicon position they both agree that are well and finally we could use |
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| 0:01:24 | quantum oscillations to prove that this the like and that position is right |
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| 0:01:29 | this is possible because the electronic structure and in particular the from a service depends |
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| 0:01:34 | very sensitively on the second that position |
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| 0:01:38 | as a result we obtain a very precise knowledge about the lattice structure fiftysome wrote |
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| 0:01:42 | into silicon two and he obtained a very precise knowledge about its electronic structure |
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| 0:01:48 | in particular we know that is this got these two from a sophistry |
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| 0:01:53 | so one of the implications |
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| 0:01:54 | first |
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| 0:01:55 | we know that the whole the fact shows a very justine to bend behavior and |
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| 0:02:00 | having proving that there are two from is to fit sheets |
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| 0:02:03 | and having measure then will allow for a very detailed |
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| 0:02:07 | description of the whole the fact and all that electronic transport properties |
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| 0:02:11 | more generally |
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| 0:02:13 | we have found that this summer stuff as topology depends very sensitively on the silly |
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| 0:02:18 | kinds that position and this is very common to the whole family of materials |
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| 0:02:22 | for the i'm take tides it's the iron thousand are an angle which is equivalent |
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| 0:02:27 | to the silicon that position and in the i don't think tied it determines the |
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| 0:02:31 | magnetic and superconducting purpose it properties of the material |
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| 0:02:35 | finally the feast and wrote into silicon two is an idea reference component to determine |
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| 0:02:40 | wrote them to select into it has got |
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| 0:02:43 | same structure same that just parameters even this that position of the silicon atoms is |
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| 0:02:48 | the same |
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| 0:02:49 | but there's one difference that element has one electron lesson it's for f show |
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| 0:02:54 | and it is this what electron missing which determines all the interesting properties of a |
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| 0:02:59 | tableau doomed to so they can to |
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| 0:03:02 | i like transform one band very close to the filming energy which hybrid eyes is |
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| 0:03:07 | why they can't affect with the connection electrons and thereby forms a re normalized that |
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| 0:03:12 | this we normalize spent has a much larger |
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| 0:03:15 | for me weight vector |
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| 0:03:17 | constituting a large from a surface |
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| 0:03:20 | the system wrote into silicon to has a full for actual lying well be though |
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| 0:03:25 | the frame energy and b are left with only the connection electrons in that sense |
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| 0:03:29 | it represents a small from a surface reference to that of remote into silicon two |
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| 0:03:35 | we can now take the measurements on the system wrote into is like into and |
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| 0:03:39 | compare them to those done previously on the travel wrote into silicon two |
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| 0:03:44 | we find very different angular dependencies of the observed quantum oscillations |
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| 0:03:49 | and therefore we can rule out if small for mischievous configuration for the tableau them |
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| 0:03:54 | to so that kinda |
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| 0:03:56 | as a conclusion our measurements highlight the prisons of the large from a surface in |
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| 0:04:01 | it or converging to select and |
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