tag:blogger.com,1999:blog-13869903.post1441496150534622975..comments2024-03-28T04:15:44.459-05:00Comments on nanoscale views: Graphene, part IDouglas Natelsonhttp://www.blogger.com/profile/13340091255404229559noreply@blogger.comBlogger8125tag:blogger.com,1999:blog-13869903.post-78092172977997551972018-04-23T22:21:42.497-05:002018-04-23T22:21:42.497-05:00can graphene be used as a superconductor?<a href="http://www.ezonetoday.com/2017/01/graphene.html" rel="nofollow">can graphene be used as a superconductor?</a>simonhttps://www.blogger.com/profile/03502978236414424699noreply@blogger.comtag:blogger.com,1999:blog-13869903.post-47237471802249216242009-11-19T00:52:50.167-06:002009-11-19T00:52:50.167-06:00One thing is for sure. Columbia University leads t...One thing is for sure. Columbia University leads the graphene fad. They have another paper in this week's Nature. Two weeks in a row. Not bad, huh?sylownoreply@blogger.comtag:blogger.com,1999:blog-13869903.post-69337171431806381652009-11-17T11:08:28.545-06:002009-11-17T11:08:28.545-06:00A single one-atom thick layer of graphene is visib...A single one-atom thick layer of graphene is visible! Graphene optical absorption is (pi)(alpha), 3.141593/137.0360 ~ 2.29%. It has a refractive index around 300,<br /><br />http://math.ucr.edu/home/baez/week277.html<br />Science 320 1308 (2008)<br />http://onnes.ph.man.ac.uk/nano/Publications/Science_2008fsc.pdf<br />arXiv:0812.1116<br /><br />MgB2, CrB2, TiB2 ZrB2 have 2-D graphenoid boron sheets spaced by M(+2). Cook 'em up with Me3SiCl to isolate the sheets? Ion-exchange with gemini surfactant to intercalcate and swell the sheets apart? Don't entrust a physicist or engineer with a stuff problem. They are skilled with things.Uncle Alnoreply@blogger.comtag:blogger.com,1999:blog-13869903.post-86713250995483772872009-11-17T08:29:18.142-06:002009-11-17T08:29:18.142-06:00woot - Yes, condensed matter tends to be faddish. ...woot - Yes, condensed matter tends to be faddish. There is a large pool of people, each with their particular tool or expertise (some specific electronic structure calculation or scattering technique or thermodynamic measurement or scanned probe), and when a new material system comes along that is sufficiently interesting, they pounce. The superconductivity community leaped on MgB2 pounded the whole area into submission in about a year. To some extent, the 2d electron and nanotube communities are doing the same thing to graphene. My personal attitude with graphene, as with nanotubes, has been to stay out unless I have a particular capability or experiment that I think is truly unique and can address some question that is important and otherwise being ignored.<br /><br />Antonio - Possibly the best professional service I've done to the CM community was hunting down the abstracts from the Geim, Kim, DeHeer, and McEuen groups (all submitted to different sorting categories) and sticking them all in one session. That was fun.<br /><br />Alex - I largely agree, in the sense that I am tired of papers on graphene where some effect is measured that either was predicted long before or is perfectly understood within a simple single-particle picture. Similarly, mobility or sub-threshold slope contests hold no charm for me. I think experimental probes of Klein tunneling are cute, as that's an effect that is not easy to access in any other system that I know about. The fractional quantum Hall papers from this past week are also interesting, since the FQHE really looks at electron-electron interactions, something largely ignored so far.<br /><br />Don - I think you may be overstating the role of ease of entry into the field; there are lots of materials that are easy to get that haven't had the same excitement. It's the combo of ease of access and the comparative forgivingness of the system. Also, you're absolutely right that the scotch tape approach is very far from industrial applications. Still, between the SiC folks and the CVD-on-Cu approach, this seems more likely to be applicable than nanotubes.Douglas Natelsonhttps://www.blogger.com/profile/13340091255404229559noreply@blogger.comtag:blogger.com,1999:blog-13869903.post-83874564933049202162009-11-17T07:59:49.028-06:002009-11-17T07:59:49.028-06:00All good points. But it seems clear that the "...All good points. But it seems clear that the "ease of preparation" is solely responsible for the recent explosion of interest, no? Much of the rest (maybe not the "relativistic" dispersion relation) was well known when Millie Dresselhaus and others were looking at intercalated graphite 30 years ago.<br /><br />It also seems that the ease of preparation cuts both ways for graphene, as it does for nanotubes. One-of-a-kind free-floating samples assembled using GSWT (graduate student with tweezers) may have a low barrier to entry, but they are not the basis of a technology.Don Monroehttps://www.blogger.com/profile/14057058447791467875noreply@blogger.comtag:blogger.com,1999:blog-13869903.post-9362738835341222042009-11-17T07:46:12.860-06:002009-11-17T07:46:12.860-06:00I am very interested in the graphene business, but...I am very interested in the graphene business, but I wonder if over 90% of the work in this area isn't 'me-too' science. Linear dispersions etc have existed in carbon nanotubes for a long time. Similarly the physics of 2D systems has been extensively studied in GaAs systems. So where exactly is the _new_ physics?Alex Hamiltonnoreply@blogger.comtag:blogger.com,1999:blog-13869903.post-68154422347280489922009-11-17T01:30:28.362-06:002009-11-17T01:30:28.362-06:00Dear Doug, I could not resist leaving a message in...Dear Doug, I could not resist leaving a message in your blog. <br /><br />Firstly, you hit the target in many aspects on why graphene has attracted so much interest from the basic science point of view. <br /><br />Moreover, from the applied point of view graphene is already showing its great potential and many big companies such as Samsung, Fujitsu, Intel, IBM, are investing heavily on the development of all sorts of electronic devices. SKKU and Samsung in South Korea, for instance, now produce graphene wafers routinely using simple CVD methods (hence, the issue of mass production has literally been solved). <br /><br />Moreover, the funding for graphene research worldwide is hitting close to US $ 0.5 billion (in the USA, the Department of Defense is one of the major supporters). <br /><br />Graphene is extremely stable structurally and another huge application that you will see soon is on impermeabilization of surfaces. <br /><br />Also, graphene, unlike fullerenes, has been in the realm of the physicists in the last 4 years but chemists are now moving fast into the field and I hope other wonders will come up soon enough.<br /><br />Doug, correct me if I am wrong but you were the chairman of the first graphene session of the APS March Meeting in Los Angeles in 2005. The Science paper by Nosovelov at al. had just been published a few months before in Science. I recall that in the room there were something like 20 people including Geim, Kim, de Heer, and Dresselhaus. Next year approximately 15% of all abstracts of the APS March Meeting in Portland will be on Graphene. I was lucky enough to be there too and witness the birth of a new research field. From my perspective, this is just the beginning.<br /><br />Cheers, Antonio.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-13869903.post-88331825116445282472009-11-16T23:19:33.183-06:002009-11-16T23:19:33.183-06:00Part of it is also a fad. It was like this for na...Part of it is also a fad. It was like this for nanotubes too. It's not entirely clear to me why nearly all of condensed matter wants to work on something where the danger of being scooped is so severe, but apparently they do. It's also a little puzzling to me where some of the differentiation is when it comes to getting funding. Are all of these proposals really that different, I really can't imagine that they are.wootnoreply@blogger.com