石墨烯的发现与发展历程

RANDOM WALK TO GRAPHENENobel Lecture, December 8, 2010byANDRE K. GEIMSchool of Phys i cs and Astronomy, The Un i vers i ty of Manchester, Oxford Road, Manchester M13 9PL, Un i ted K i ngdom.If one wants to understand the beaut i ful phys i cs of graphene, they w i ll be spo i led for cho i ce w i th so many rev i ews and popular sc i ence art i cles now ava i lable. I hope that the reader w i ll excuse me i f on th i s occas i on I recommend my own wr i t i ngs [1–3]. Instead of repeat i ng myself here, I have chosen to descr i be my tw i sty sc i ent ific road that eventually led to the Nobel Pr i ze. Most parts of th i s story are not descr i bed anywhere else, and i ts t i me-l i ne covers the per i od from my PhD i n 1987 to the moment when our 2004 paper, recogn i sed by the Nobel Comm i ttee, was accepted for publ i cat i on. The story naturally gets denser i n events and explanat i ons towards the end. Also, i t prov i des a deta i led rev i ew of pre-2004 l i terature and, w i th the benefit of h i nds i ght, attempts to analyse why graphene has attracted so much i nter-est. I have tr i ed my best to make th i s art i cle not only i nformat i ve but also easy to read, even for non-phys i c i sts.ZOMBIE MANAGEMENTMy PhD thes i s was called “Invest i gat i on of mechan i sms of transport relaxa-t i on i n metals by a hel i con resonance method”. All I can say i s that the stuff was as i nterest i ng at that t i me as i t sounds to the reader today. I publ i shed five journal papers and fin i shed the thes i s i n five years, the offic i al durat i on for a PhD at my i nst i tut i on, the Inst i tute of Sol i d State Phys i cs.Web of Sc i ence so-berly reveals that the papers were c i ted tw i ce, by co-authors only. The subject was dead a decade before I even started my PhD. However, every cloud has i ts s i lver l i n i ng, and what I un i quely learned from that exper i ence was that I should never torture research students by offer i ng them “zomb i e” projects. After my PhD, I worked as a staff sc i ent i st at the Inst i tute of M i cro-electron i cs Technology, Chernogolovka, wh i ch belongs to the Russ i an Academy of Sc i ences. The Sov i et system allowed and even encouraged jun i or staff to choose the i r own l i ne of research. After a year of pok i ng i n d i fferent d i rect i ons, I separated research-w i se from my former PhD superv i sor, V i ctor Petrashov, and started develop i ng my own n i che. It was an exper i mental system that was both new and doable, wh i ch was nearly an oxymoron, tak i ng i nto account the scarce resources ava i lable at the t i me at Sov i et researchi nst i tutes. I fabr i cated a sandw i ch cons i st i ng of a th i n metal film and a super-conductor separated by a th i n i nsulator. The superconductor served only to condense an external magnet i c field i nto an array of vort i ces, and th i s h i ghly i nhomogeneous magnet i c field was projected onto the film under i nvest i ga-t i on. Electron transport i n such a m i croscop i cally i nhomogeneous field (vary i ng on a subm i cron scale) was new research terr i tory, and I publ i shed the first exper i mental report on the subject [4], wh i ch was closely followed by an i ndependent paper from S i mon Bend i ng [5]. It was an i nterest i ng and reasonably i mportant n i che, and I cont i nued study i ng the subject for the next few years, i nclud i ng a spell at the Un i vers i ty of Bath i n 1991 as a postdoctoral researcher work i ng w i th S i mon.Th i s exper i ence taught me an i mportant lesson: that i ntroduc i ng a new exper i mental system i s generally more reward i ng than try i ng to find new phenomena w i th i n crowded areas. The chances of success are much h i gher where the field i s new. Of course, the fantast i c results one or i g i nally hopes for are unl i kely to mater i al i se, but, i n the process of study i ng any new system, someth i ng or i g i nal i nev i tably shows up.ONE MAN’S JUNK, ANOTHER MAN’S GOLDIn 1990, thanks to V i taly Ar i stov, d i rector of my Inst i tute i n Chernogolovka at the t i me, I rece i ved a s i x month v i s i t i ng fellowsh i p from the Br i t i sh Royal Soc i ety. Laurence Eaves and Peter Ma i n from Nott i ngham Un i vers i ty k i ndly agreed to accept me as a v i s i tor. S i x months i s a very short per i od for exper i mental work, and c i rcumstances d i ctated that I could only study de-v i ces read i ly ava i lable i n the host laboratory. Ava i lable were subm i cron GaAs w i res left over from prev i ous exper i ments, all done and dusted a few years earl i er. Under the c i rcumstances, my exper i ence of work i ng i n a poverty-str i cken Sov i et academy was helpful. The samples that my hosts cons i dered pract i cally exhausted looked l i ke a gold ve i n to me, and I started work i ng 100 hours per week to explo i t i t. Th i s short v i s i t led to two Phys. Rev. Letters of decent qual i ty [6,7], and I often use th i s exper i ence to tease my younger colleagues. When th i ngs do not go as planned and people start compla i n i ng, I provoke them by procla i m i ng ‘there i s no such th i ng as bad samples; there are only bad postdocs/students’. Search carefully and you w i ll always find someth i ng new. Of course, i t i s better to avo i d such exper i ences and explore new terr i tor i es, but even i f one i s fortunate enough to find an exper i mental system as new and exc i t i ng as graphene, met i culousness and perseverance allow one to progress much further.The pace of research at Nott i ngham was so relentless and, at the same t i me so i nsp i r i ng, that a return to Russ i a was not an opt i on. Sw i mm i ng through Sov i et treacle seemed no less than wast i ng the rest of my l i fe. So at the age of th i rty-three and w i th an h-i ndex of 1 (latest papers not yet publ i shed), I entered the Western job market for postdocs. Dur i ng the next four years I moved between d i fferent un i vers i t i es, from Nott i ngham to Copenhagen to Bath and back to Nott i ngham. Each move allowed me to get acqua i nted w i thyet another top i c or two, s i gn ificantly broaden i ng my research hor i zons. The phys i cs I stud i ed i n those years could be broadly descr i bed as mesoscop i c and i nvolved such systems and phenomena as two-d i mens i onal electron gases (2DEGs), quantum po i nt contacts, resonant tunnell i ng and the quantum Hall effect (QHE), to name but a few. In add i t i on, I became fam i l i ar w i th GaAlAs heterostructures grown by molecular beam ep i taxy (MBE) and i mproved my expert i se i n m i crofabr i cat i on and electron-beam l i thography, technolog i es I had started learn i ng i n Russ i a. All these elements came together to form the foundat i on for the successful work on graphene a decade later.DUTCH COMFORTBy 1994 I had publ i shed enough qual i ty papers and attended enough con-ferences to hope for a permanent academ i c pos i t i on. When I was offered an assoc i ate professorsh i p at the Un i vers i ty of N i jmegen, I i nstantly se i zed upon the chance of hav i ng some secur i ty i n my new post-Sov i et l i fe. The first task i n N i jmegen was of course to establ i sh myself. To th i s end, there was no start-up and no m i crofabr i cat i on to cont i nue any of my prev i ous l i nes of re-search. As resources, I was offered access to magnets, cryostats and electron i c equ i pment ava i lable at N i jmegen’s H i gh F i eld Magnet Laboratory, led by Jan Kees Maan. He was also my formal boss and i n charge of all the money. Even when I was awarded grants as the pr i nc i pal i nvest i gator (the Dutch fund i ng agency FOM was generous dur i ng my stay i n N i jmegen), I could not spend the money as I w i shed. All funds were d i str i buted through so-called ‘work i ng groups’ led by full professors. In add i t i on, PhD students i n the Netherlands could formally be superv i sed only by full professors. Although th i s probably sounds strange to many, th i s was the Dutch academ i c system of the 1990s. It was tough for me then. For a couple of years, I really struggled to adjust to the system, wh i ch was such a contrast to my joyful and product i ve years at Nott i ngham. In add i t i on, the s i tuat i on was a b i t surreal because outs i de the un i vers i ty walls I rece i ved a warm-hearted welcome from everyone around, i nclud i ng Jan Kees and other academ i cs.St i ll, the research opportun i t i es i n N i jmegen were much better than i n Russ i a and, eventually, I managed to surv i ve sc i ent ifically, thanks to help from abroad. Nott i ngham colleagues (i n part i cular Mohamed Hen i n i) prov i ded me w i th 2DEGs that were sent to Chernogolovka, where Sergey Dubonos, a close colleague and fr i end from the 1980s, m i crofabr i cated requested dev i ces. The research top i c I eventually found and later focused on can be referred to as mesoscop i c superconduct i v i ty. Sergey and I used m i cron-s i zed Hall bars made from a 2DEG as local probes of the magnet i c field around small superconduct i ng samples. Th i s allowed measurements of the i r magnet i sat i on w i th accuracy suffic i ent to detect not only the entry and ex i t of i nd i v i dual vort i ces but also much more subtle changes. Th i s was a new exper i mental n i che, made poss i ble by the development of an or i g i nal techn i que of ball i st i c Hall m i cromagnetometry [8]. Dur i ng the next fewyears, we explo i ted th i s n i che area and publ i shed several papers i n Nature and Phys. Rev. Letters wh i ch reported a paramagnet i c Me i ssner effect, vort i ces carry i ng fract i onal flux, vortex configurat i ons i n confined geometr i es and so on. My w i fe Ir i na Gr i gor i eva, an expert i n vortex phys i cs [9], could not find a job i n the Netherlands and therefore had plenty of t i me to help me w i th conquer i ng the subject and wr i t i ng papers. Also, Sergey not only made the dev i ces but also v i s i ted N i jmegen to help w i th measurements. We establ i shed a very product i ve modus operand i where he collected data and I analysed them w i th i n an hour on my computer next door to dec i de what should be done next.A SPELL OF LEVITYThe first results on mesoscop i c superconduct i v i ty started emerg i ng i n 1996, wh i ch made me feel safer w i th i n the Dutch system and also more i nqu i s i-t i ve. I started look i ng around for new areas to explore. The major fac i l i ty at N i jmegen’s H i gh F i eld Lab was powerful electromagnets. They were a major headache, too. These magnets could prov i de fields up to 20 T, wh i ch was somewhat h i gher than 16 to 18 T ava i lable w i th the superconduct i ng magnets that many of our compet i tors had. On the other hand, the elec-tromagnets were so expens i ve to run that we could use them only for a few hours at n i ght, when electr i c i ty was cheaper. My work on mesoscop i c super-conduct i v i ty requ i red only t i ny fields (< 0.01T), and I d i d not use the electro-magnets. Th i s made me feel gu i lty as well as respons i ble for com i ng up w i th exper i ments that would just i fy the fac i l i ty’s ex i stence. The only compet i t i ve edge I could see i n the electromagnets was the i r room temperature (T) bore. Th i s was often cons i dered as an extra d i sadvantage because research i n condensed matter phys i cs typ i cally requ i res low, l i qu i d-hel i um T. The con-trad i ct i on prompted me, as well as other researchers work i ng i n the lab, to ponder on h i gh-field phenomena at room T. Unfortunately, there were few to choose from.Eventually, I stumbled across the mystery of so-called magnet i c water. It i s cla i med that putt i ng a small magnet around a hot water p i pe prevents format i on of scale i ns i de the p i pe. Or i nstall such a magnet on a water tap, and your kettle w i ll never suffer from chalky depos i ts. These magnets are ava i lable i n a great var i ety i n many shops and on the i nternet. There are also hundreds of art i cles wr i tten on th i s phenomenon, but the phys i cs beh i nd i t rema i ns unclear, and many researchers are scept i cal about the very ex i stence of the effect [10]. Over the last fifteen years I have made several attempts to i nvest i gate “magnet i c water” but they were i nconclus i ve, and I st i ll have noth i ng to add to the argument. However, the ava i lab i l i ty of ultra-h i gh fields i n a room T env i ronment i nv i ted lateral th i nk i ng about water. Bas i cally, i f magnet i c water ex i sted, I thought, then the effect should be clearer i n 20 T rather than i n typ i cal fields of <0.1 T created by standard magnets.W i th th i s i dea i n m i nd and, allegedly, on a Fr i day n i ght, I poured water i ns i de the lab’s electromagnet when i t was at i ts max i mum power. Pour i ngwater i n one's equ i pment i s certa i nly not a standard sc i ent ific approach, and I cannot recall why I behaved so ‘unprofess i onally’. Apparently, no one had tr i ed such a s i lly th i ng before, although s i m i lar fac i l i t i es ex i sted i n several places around the world for decades. To my surpr i se, water d i d not end up on the floor but got stuck i n the vert i cal bore of the magnet. Humberto Carmona, a v i s i t i ng student from Nott i ngham, and I played for an hour w i th the water by break i ng the blockage w i th a wooden st i ck and chang i ng the field strength. As a result, we saw balls of lev i tat i ng water (F i gure 1). Th i s was awesome. It took l i ttle t i me to real i se that the phys i cs beh i nd was good old d i amagnet i sm. It took much longer to adjust my i ntu i t i on to the fact that the feeble magnet i c response of water (~10–5), b i ll i ons of t i mes weaker than that of i ron, was suffic i ent to compensate the earth’s grav i ty. Many colleagues, i nclud i ng those who worked w i th h i gh magnet i c fields all the i r l i ves, were flabbergasted, and some of them even argued that th i s was a hoax.I spent the next few months demonstrat i ng magnet i c lev i tat i on to colleagues and v i s i tors, as well as try i ng to make a ‘non-boffin’i llustrat i on for th i s beaut i ful phenomenon. Out of the many objects that we had float i ng i ns i de the magnet, i t was the i mage of a lev i tat i ng frog (F i gure 1) that started the med i a hype. More i mportantly, though, beh i nd all the med i a no i se, th i s i mage found i ts way i nto many textbooks. However qu i rky, i t has become a beaut i ful symbol of ever-present d i amagnet i sm, wh i ch i s no longer perce i ved to be extremely feeble. Somet i mes I am stopped at conferences by people excla i m i ng “I know you! Sorry, i t i s not about graphene. I start my lectures w i th show i ng your frog. Students always want to learn how i t could fly.” The frog story, w i th some i ntr i cate phys i cs beh i nd the stab i l i ty of d i amagnet i c lev i tat i on, i s descr i bed i n my rev i ew i n Phys i cs Today [11].F i gure 1. Lev i tat i ng moments i n N i jmegen. Left – Ball of water (about 5 cm i n d i ameter) freely floats i ns i de the vert i cal bore of an electromagnet. R i ght – The frog that learned to fly. Th i s i mage cont i nues to serve as a symbol show i ng that magnet i sm of ‘nonmagnet i c th i ngs’, i nclud i ng humans, i s not so negl i g i ble. Th i s exper i ment earned M i chael Berry and me the 2000 Ig Nobel Pr i ze. We were asked first whether we dared to accept th i s pr i ze, and I take pr i de i n our sense of humour and self-deprecat i on that we d i d.FRIDAY NIGHT EXPERIMENTSThe lev i tat i on exper i ence was both i nterest i ng and add i ct i ve. It taught me the i mportant lesson that pok i ng i n d i rect i ons far away from my i mmed i ate area of expert i se could lead to i nterest i ng results, even i f the i n i t i al i deas were extremely bas i c. Th i s i n turn i nfluenced my research style, as I started mak i ng s i m i lar exploratory detours that somehow acqu i red the name ‘Fr i day n i ght exper i ments’. The term i s of course i naccurate. No ser i ous work can be accompl i shed i n just one n i ght. It usually requ i res many months of lateral th i nk i ng and d i gg i ng through i rrelevant l i terature w i thout any clear i dea i n s i ght. Eventually, you get a feel i ng – rather than an i dea – about what could be i nterest i ng to explore. Next, you g i ve i t a try, and normally you fa i l. Then, you may or may not try aga i n. In any case, at some moment you must dec i de (and th i s i s the most d i fficult part) whether to cont i nue further efforts or cut losses and start th i nk i ng of another exper i ment. All th i s happens aga i nst the backdrop of your ma i n research and occup i es only a small part of your t i me and bra i n.Already i n N i jmegen, I started us i ng lateral i deas as under- and post-graduate projects, and students were always exc i ted to buy a p i g i n a poke. Kostya Novoselov, who came to N i jmegen as a PhD student i n 1999, took part i n many of these projects. They never lasted for more than a few months, i n order not to jeopard i se a thes i s or career progress i on. Although the enthus i asm i nev i tably van i shed towards the end, when the pred i ctable fa i lures mater i al i sed, some students later confided that those exploratory detours were i nvaluable exper i ences.Most surpr i s i ngly, fa i lures somet i mes fa i led to mater i al i se. Gecko tape i s one such example. Acc i dentally or not, I read a paper descr i b i ng the mechan i sm beh i nd the amaz i ng cl i mb i ng ab i l i ty of geckos [12]. The phys i cs i s rather stra i ghtforward. Gecko’s toes are covered w i th t i ny ha i rs. Each ha i r attaches to the oppos i te surface w i th a m i nute van der Waals force (i n the nN range), but b i ll i ons of ha i rs work together to create a form i dable attract i on suffic i ent to keep geckos attached to any surface, even a glass ce i l i ng. In part i cular, my attent i on was attracted by the spat i al scale of the i r ha i rs. They were subm i cron i n d i ameter, the standard s i ze i n research on mesoscop i c phys i cs. After toy i ng w i th the i dea for a year or so, Sergey Dubonos and I came up w i th procedures to make a mater i al that m i m i cked a gecko’s ha i ry feet. He fabr i cated a square cm of th i s tape, and i t exh i b i ted notable adhes i on [13]. Unfortunately, the mater i al d i d not work as well as a gecko’s feet, deter i orat i ng completely after a couple of attachments. St i ll, i t was an i mportant proof-of-concept exper i ment that i nsp i red further work i n the field. Hopefully, one day someone w i ll develop a way to repl i cate the h i erarch i cal structure of gecko’s setae and i ts self-clean i ng mechan i sm. Then gecko tape can go on sale.BETTER TO BE WRONG THAN BORINGWh i le prepar i ng for my lecture i n Stockholm, I comp i led a l i st of my Fr i day n i ght exper i ments. Only then d i d I real i se a stunn i ng fact. There were two dozen or so exper i ments over a per i od of approx i mately fifteen years and, as expected, most of them fa i led m i serably. But there were three h i ts: lev i tat i on, gecko tape and graphene. Th i s i mpl i es an extraord i nary success rate: more than 10%. Moreover, there were probably near-m i sses, too. For example, I once read a paper [14] about g i ant d i amagnet i sm i n FeGeSeAs alloys, wh i ch was i nterpreted as a s i gn of h i gh-T superconduct i v i ty. I asked Lamarches for samples and got them. Kostya and I employed ball i st i c Hall magnetometry to check for g i ant d i amagnet i sm but found noth i ng, even at 1 K. Th i s happened i n 2003, well before the d i scovery of i ron pn i ct i de superconduct i v-i ty, and I st i ll wonder whether there were any small i nclus i ons of a supercon-duct i ng mater i al wh i ch we m i ssed w i th our approach. Another m i ss was an attempt to detect “heartbeats” of i nd i v i dual l i v i ng cells. The i dea was to use 2DEG Hall crosses as ultrasens i t i ve electrometers to detect electr i cal s i gnals due to phys i olog i cal act i v i ty of i nd i v i dual cells. Even though no heartbeats were detected wh i le a cell was al i ve, our sensor recorded huge voltage sp i kes at i ts “last gasp” when the cell was treated w i th excess alcohol [15]. Now I attr i bute th i s near-m i ss to the unw i se use of yeast, a very dormant m i cro-organ i sm. Four years later, s i m i lar exper i ments were done us i ng embryon i c heart cells and – what a surpr i se – graphene sensors, and they were successful i n detect i ng such b i oelectr i cal act i v i ty [16].Frankly, I do not bel i eve that the above success rate can be expla i ned by my lateral i deas be i ng part i cularly good. More l i kely, th i s tells us that pok i ng i n new d i rect i ons, even randomly, i s more reward i ng than i s generally perce i ved. We are probably d i gg i ng too deep w i th i n establ i shed areas, leav i ng plenty of unexplored stuff under the surface, just one poke away. When one dares to try, rewards are not guaranteed, but at least i t i s an adventure.THE MANCUNIAN WAYBy 2000, w i th mesoscop i c superconduct i v i ty, d i amagnet i c lev i tat i on and four Nature papers under my belt, I was well placed to apply for a full professorsh i p. Colleagues were rather surpr i sed when I chose the Un i vers i ty of Manchester, decl i n i ng a number of seem i ngly more prest i g i ous offers. The reason was s i mple.M i ke Moore, cha i rman of the search comm i ttee, knew my w i fe Ir i na when she was a very successful postdoc i n Br i stol rather than my co-author and a part-t i me teach i ng lab techn i c i an i n N i jmegen. He suggested that Ir i na could apply for the lecturesh i p that was there to support the professorsh i p. After s i x years i n the Netherlands, the i dea that a husband and w i fe could offic i ally work together had not even crossed my m i nd. Th i s was the dec i s i ve factor. We apprec i ated not only the poss i b i l i ty of sort i ng out our dual career problems but also felttouched that our future colleagues cared. We have never regretted the move.So i n early 2001, I took charge of several d i lap i dated rooms stor i ng anc i ent equ i pment of no value, and a start-up grant of £100K. There were no central fac i l i t i es that I could explo i t, except for a hel i um l i quefier. No problem. I followed the same rout i ne as i n N i jmegen, comb i n i ng help from other places, espec i ally Sergey Dubonos. The lab started shap i ng up surpr i s i ngly qu i ckly. W i th i n half a year, I rece i ved my first grant of £500K, wh i ch allowed us to acqu i re essent i al equ i pment. Desp i te be i ng consumed w i th our one year old daughter, Ir i na also got her start i ng grant a few months later. We i nv i ted Kostya to jo i n us as a research fellow (he cont i nued to be offic i ally reg i stered i n N i jmegen as a PhD student unt i l 2004 when he defended h i s thes i s there). And our group started generat i ng results that led to more grants that i n turn led to more results.By 2003 we publ i shed several good-qual i ty papers i nclud i ng Nature, Nature Mater i als and Phys. Rev. Letters, and we cont i nued beefing up the labora-tory w i th new equ i pment. Moreover, thanks to a grant of £1.4M (research i nfrastructure fund i ng scheme masterm i nded by the then sc i ence m i n i ster Dav i d Sa i nsbury), Ern i e H i ll from the Department of Computer Sc i ences and I managed to set up the Manchester Centre for Mesosc i ence and Nanotechnology. Instead of pour i ng the w i ndfall money i nto br i cks-and-mortar, we ut i l i sed the ex i st i ng clean room areas (~250 m2) i n Computer Sc i ences. Those rooms conta i ned obsolete equ i pment, and i t was thrown away and replaced w i th state-of-the-art m i crofabr i cat i on fac i l i t i es, i nclud i ng a new electron-beam l i thography system. The fact that Ern i e and I are most proud of i s that many groups around the world have more expens i ve fac i l i t i es but our Centre has cont i nuously, s i nce 2003, been produc i ng new structures and dev i ces. We do not have a posh horse here that i s for show, but rather a draft horse that has been work i ng really hard.Whenever I descr i be th i s exper i ence to my colleagues abroad, they find i t d i fficult to bel i eve that i t i s poss i ble to establ i sh a fully funct i onal labora-tory and a m i crofabr i cat i on fac i l i ty i n less than three years and w i thout an astronom i cal start-up grant. If not for my own exper i ence, I would not bel i eve i t e i ther. Th i ngs progressed unbel i evably qu i ckly. The Un i vers i ty was support i ve, but my greatest thanks are reserved spec ifically for the respons i ve mode of the UK Eng i neer i ng and Phys i cal Sc i ences Research Counc i l (EPSRC). The fund i ng system i s democrat i c and non-xenophob i c. Your pos i t i on i n an academ i c h i erarchy or an old-boys network counts for l i ttle. Also, ‘v i s i onary i deas’ and grand prom i ses to ‘address soc i al and econom i c needs’ play l i ttle role when i t comes to the peer rev i ew. In truth, the respons i ve mode d i str i butes i ts money on the bas i s of a recent track record, whatever that means i n d i fferent subjects, and the fund i ng normally goes to researchers who work both effic i ently and hard. Of course, no system i s perfect, and one can always hope for a better one. However, paraphras i ng W i nston Church i ll, the UK has the worst research fund i ng system, except for all the others that I am aware of.THREE LITTLE CLOUDSAs our laboratory and Nanotech Centre were shap i ng up, I got some spare t i me for th i nk i ng of new research detours. Gecko tape and the fa i led attempts w i th yeast and quas i-pn i ct i des took place dur i ng that t i me. Also, Serge Morozov, a sen i or fellow from Chernogolovka, who later became a regular v i s i-tor and i nvaluable collaborator, wasted h i s first two v i s i ts on study i ng magnet i c water. In the autumn of 2002, our first Manchester PhD student, Da J i ang, arr i ved, and I needed to i nvent a PhD project for h i m. It was clear that for the first few months he needed to spend h i s t i me learn i ng Engl i sh and gett i ng acqua i nted w i th the lab. Accord i ngly, as a starter, I suggested to h i m a new lateral exper i ment. It was to make films of graph i te ‘as th i n as poss i ble’ and, i f successful, I prom i sed we would then study the i r ‘mesoscop i c’ propert i es. Recently, try i ng to analyse how th i s i dea emerged, I recalled three badly shaped thought clouds.One cloud was a concept of ‘metall i c electron i cs’. If an external electr i c field i s appl i ed to a metal, the number of charge carr i ers near i ts surface changes, so that one may expect that i ts surface propert i es change, too. Th i s i s how modern sem i conductor electron i cs works. Why not use a metal i nstead of s i l i con? As an undergraduate student, I wanted to use electr i c field effect (EFE) and X-ray analys i s to i nduce and detect changes i n the latt i ce constant. It was naïve because s i mple est i mates show that the effect would be negl i g i ble. Indeed, no d i electr i c allows fields much h i gher than 1V/nm, wh i ch translates i nto max i mum changes i n charge carr i er concentrat i on n at the metal surface of about 1014 per cm2. In compar i son, a typ i cal metal (e.g., Au) conta i ns ~1023 electrons per cm3 and, even for a 1 nm th i ck film, th i s y i elds relat i ve changes i n n and conduct i v i ty of ~1%, leav i ng as i de much smaller changes i n the latt i ce constant.Prev i ously, many researchers asp i red to detect the field effect i n metals. The first ment i on i s as far back as 1902, shortly after the d i scovery of the electron. J. J. Thomson (1906 Nobel Pr i ze i n Phys i cs) suggested to Charles Mott, the father of Nev i ll Mott (1977 Nobel Pr i ze i n Phys i cs), to look for the EFE i n a th i n metal film, but noth i ng was found [17]. The first attempt to measure the EFE i n a metal was recorded i n sc i ent ific l i terature i n 1906 [18]. Instead of a normal metal, one could also th i nk of sem i metals such as b i smuth, graph i te or ant i mony wh i ch have a lot fewer carr i ers. Over the last century, many researchers used B i films (n ~1018 cm–3) but observed only small changes i n the i r conduct i v i ty [19,20]. Aware of th i s research area and w i th exper i ence i n GaAlAs heterostructures, I was cont i nuously, albe i t casually, look i ng for other cand i dates, espec i ally ultra-th i n films of superconductors i n wh i ch the field effect can be ampl ified i n prox i m i ty to the superconduct i ng trans i t i on [21,22]. In N i jmegen, my enthus i asm was once sparked by learn i ng about nm-th i ck Al films grown by MBE on top of GaAlAs heterostructures but, after est i mat i ng poss i ble effects, I dec i ded that the chances of success were so poor i t was not worth try i ng.Carbon nanotubes were the second cloud hang i ng around i n the late。