你 的鉛筆 會 超導嗎? 林秀豪 清華大學物理系 大綱 • 什麼是凝態物理? • 你了解自己的鉛筆嗎? • 你了解電子的自旋嗎? • 你了解奈米傳輸嗎? • 結語 什麼是 凝態物理? arly seen on both experimental and oretical curves. For the regions with only From Wikipedia I while the Hall coefficient reverses its sig reflecting the fact that RH is proportional Condensed matter physics is the field of physics that deals with the macroscopic physical properties of matter. In particular, it is concerned with the "condensed" phases that appear whenever the number of constituents in a system is extremely large and the interactions between the constituents are strong. The most familiar examples of condensed phases are solids and liquids, which arise from the bonding and electromagnetic force between atoms. More exotic condensed phases include the superfluid and the Bose-Einstein condensate found in certain atomic systems at very low temperatures, the superconducting phase exhibited by conduction electrons in certain materials, and the ferromagnetic and antiferromagnetic phases of spins on atomic lattices. 4 arly seen on both experimental and oretical curves. For the regions with only From Wikipedia II while the Hall coefficient reverses its sig reflecting the fact that RH is proportional Condensed matter physics is by far the largest field of contemporary physics.A lot of progress has also been made in theoretical condensed matter physics. By one estimate, one third of all American physicists identify themselves as condensed matter physicists. Historically, condensed matter physics grew out of solid-state physics, which is now considered one of its main subfields. The term "condensed matter physics" was apparently coined by Philip Anderson when he renamed his research group previously "solid-state theory" - in 1967. In 1978, the Division of Solid State Physics at the American Physical Society was renamed as the Division of Condensed Matter Physics. Condensed matter physics has a large overlap with chemistry, materials science, nanotechnology and engineering. 5 arly seen on both experimental and oretical curves. For the regions with only From Wikipedia III while the Hall coefficient reverses its sig reflecting the fact that RH is proportional t One of the reasons for calling the field "condensed matter physics" is that many of the concepts and techniques developed for studying solids actually apply to fluid systems. For instance, the conduction electrons in an electrical conductor form a type of quantum fluid with essentially the same properties as fluids made up of atoms. In fact, the phenomenon of superconductivity, in which the electrons condense into a new fluid phase in which they can flow without dissipation, is very closely analogous to the superfluid phase found in helium 3 at low temperatures. 6 Many Means Beauty? 格物致知? 化約主義的科學家? 數大便是美? 7 Why Many? 8 What is Temperature? 請問,一顆在磁場中繞圈圈的電子, 它的溫度是多少呢? 9 Temperature 因為無知,所以才有溫度的概念。 溫度是能量不 守恆的產物 10 Some Quantum Flavor • 量子物理讓我們對 一顆粒子也可以很 無知。 • 所以,數不必大, 也可以很美。 • 因為無知,所以處 處驚奇。 11 Quantum Interferences 量子分身術 12 你了解 自己的鉛筆嗎? Why pencil can write? 為什麼我們可以用 鉛筆寫字呢? 又為什麼可以用橡 皮擦來擦掉呢? 14 Shinny Graphite? 黑金黑金的… 為什麼呢?早點 想到可能可以拿 Nobel Prize 喔! 15 Cheap Nanotechnology 我黏,我撕,我黏 我做實驗! 16 r graphene), to , and to study Despite being emain of high nic transport is distances. No ss is known to ontinuous under LG, we demonct transistor in annel can be n and hole gases . e prepared by ated peeling) of ented pyrolytic h was found to d us to prepare e. Thicker films 6m across and Figure 1 shows ilms, including also (15)^. To erties, we prorminal Hall bar an oxidized Si ge Vg could be more than 60 e focus on the thinnest (FLG) st one, two, or l FLG devices ical electronic 2D semimetal, e complex (2D transforms the shallow-overlap semimetal into either completely electron or completely hole conductor through a mixed state where both electrons and holes are present (Fig. 2). The three regions of electric field doping are clearly seen on both experimental and theoretical curves. For the regions with only way, as 1/ne. The resistivity also follows the standard dependence Dj1 0 G 0 ne6 (where 6 is carrier mobility). In the mixed state, G changes little with Vg, indicating the substitution of one type of carrier with another, while the Hall coefficient reverses its sign, reflecting the fact that RH is proportional to Not-so-cheap Part... Fig. 1. Graphene films. (A) Photograph (in normal white light) of a relatively large multilayer graphene flake with thickness È3 nm on top of an oxidized Si wafer. (B) Atomic force microscope (AFM) image of 2 6m by 2 6m area of this flake near its edge. Colors: dark brown, SiO2 surface; orange, 3 nm height above the SiO2 surface. (C) AFM image of single-layer graphene. Colors: dark brown, SiO2 surface; brown-red (central area), 0.8 nm height; yellow-brown (bottom left), 1.2 nm; orange (top left), 2.5 nm. Notice the folded part of the film near the bottom, which exhibits a differential height of È0.4 nm. For details of AFM imaging of single-layer graphene, see (15). (D) Scanning electron microscope image of one of our experimental devices prepared from FLG. (E) Schematic view of the device in (D). 這就不太便宜了… 17 Relativity in Pencil Flakes? 在鉛筆屑堆,找到相對論。 18 Birth of Carbon Era? 19 Magnetic Carbon Foam 20 -6 Magnetic Moment m (10 emu) 4 3 (a) %6 猜猜看… t 1 %6 0 0:5 0:5 t s 哪個是打爛前? 哪個是打爛後? -1 -2 -3 -5 0 5 Magnetic Field (kOe) 10 (b) Esquinazi et al., PRL 91, 227101 (2003) -6 ent ms (10 emu) Magnetic t 2 -10 -6 Strange Magnet? the area of to largest magn that the-2 magnetic signal is not correlated the t No. 4). We note that meas samples indicate that phy in -3any irradiation stage. For comparison, in #Fd ties of the measured surf show a -10topography line moment scans magnetic fromoM -5 0 and 5 magnetic 10 rough estimate only [17 Field (kOe) normal to theMagnetic magnetic domain structure at stag moment measured by M The MFM(b)pictures shown in Fig. 3 were obtain distance of 50 nm between tip and surface. Bec 1 the small coercive field of the magnetic surface influence of the magnetic tip we have observed magnetic domain distribution depends on the d 0.1 between tip and surface. Theoretically, the pha 1 10by MFM 100 1000 !" measured should be proportional Irradiated Total Charge C (µC) magnetic force gradient, which should depend FIG. 2. (a) Magnetic moment (in units of 10 emu) measured at T & 300 K as a function of thetip magnetic field asand in distance between the apex sample surfa FIG. 3. Top: Phase gradie Fig. 1(b), %5 for sample 2 before (!) and after (") proton perature from MFM at thre magnetic moment as between a "hirradiation. ' ## (b) ,Measured beingsaturation # the distance the tip a ing to the irradiation stages function of the total irradiated charge C for sample 1 (") at the bottom left of the fig for sample 2 (!).position The dashed lineof is the function m & theandeffective the magnetic inof phase moment gradient line scans 0:22)10 emu=!C *C . at stage No. 2. Measuring !" as a function of h we estimate # ! 227201-3 100# nm. With this value we estimate the maximu netic moment observed by the tip m ! 3 $ 10%15 the area of largest magnetic moment (stages No No. 4). We note that measurements on different m samples indicate that # depends on the magnetic ties of the measured surface and therefore the ca magnetic moment from MFM data should be tak rough estimate only [17]. Assuming that the m moment measured by MFM corresponds to a re Saturation Moment ms (10 emu) Ct , our results indicate a relation of the type ms / Ct ; see Fig. 2(b). It is interesting to note that after the No. 4 irradiation the magnetic moment of sample 1 decreases [see Fig. 1(a)] indicating that there might be a competition between the produced disorder and the implanted charge, which determines the total magnetic ordering. Hysteresis loops were measured at 5, 300, and 380 K. In this temperature range there is no significant change of the ferromagnetic loops with temperature. This result is 1 21 Zigzag Domain Wall 在石墨平原上的奈米懸崖 22 Edge State 活在奈米懸崖邊的電子們 23 Have Some Calcium... y used to write or draw ept indefinitely or erased perty that encourages different kind has led Weller scovery of superconducting operties, as reported on page ipulated the material to r with a critical temperature mply adding the common the less-common element onding Tc of 6.5 K). In assium and sodium as erature did not exceed 1 K, techniques that yielded an The new results1 have been d quickly4 and theoretical l of explanations (see, for 2,000 Graphite (002) C6Yb (004) C6Yb (002) 0 10 C6Yb (004) Graphite (004) 20 Graphite (004) FC –4 Graphite (006) –6 C6Yb (006) Yb2O3 (111) –8 30 –10 0 40 ZFC 50 θ (°) 2θ 60 C6Yb 70 C6Yb (008) 80 4 6 8 10 12 Figure 1 X-ray diffraction pattern of highly oriented pyrolytic Temperature (K) graphite 90 2 intercalated with ytterbium. These data were taken using a Bragg–Brentano geometry with Cu Kα radiation. As a consequence of this, only the (00l) peaks may be sampled. Top: The modelled10 using a stage-1 graphite c derived structure d intercalation compounds with a c∗ axis sandwich depth (C–Yb–C) of 4.57 Å. 100 Measurements for C6 Ca have a sandwich depth (C–Ca–C) of 4.51± 0.02 Å, in reasonable agreement with the study in ref. 11, which determines a value of 4.524 Å. In the structure of80 C6 Yb the graphite sheets have an A–A registration whereas the ytterbium have an α–β registration. Calculations based on peak intensities reveal that 13% of the sample volume fraction is made up of C6 Yb. From our analysis we find that the 60contamination of Yb2 O3 is less than 1% after surface abrasion. 補充點鈣質, 有益身心健康! 17 40 40 0.00 –2 –12 60 0.02 Moment (e.m.u. cm–3) 1,000 stivity (µΩ cm) (002) 2 80 b 2 Moment (e.m.u. cm–3) Intensity (counts) Ca 0 100 0 500 Ma ZFC c Ca 1,500 Ca –8 Ma a Mb –6 –12 20 –0.02 0 –0.04 0FC 20 –0.06 Figure 2 The te –0.08 resistivity for C C6 Ca (b). These –0.10 ZFfi c∗ axis. These measurement an –0.12 There is0a clear 5 d, The supercon results of the ma type-II supercon whereas there is 2.5 is approxim 2.0 critica upper parameter of 2 across the 1.5 theo Landau electron mas of1.0 the24ratio Field (kOe) ETTERS –4 –10 Resistivity (µΩ cm) Figure 1 Crystal structure of C6Ca. The unit cell is rhombohedral with the calcium atoms in green and graphene sheet in red. noscience Delft, Delft University , 2628 CJ Delft, The Netherlands. mail: t.m.klapwijk@tnw.tudelft.nl R 2005 | www.nature.com/naturephysics Mb Ca K ays a fascinating playground s to explain the world in orld is not a static entity. It e ideas and materials that lenges. Most people would ent in architecture or on the nsed-matter physics has a th advances in materials and are sometimes part of the etimes more hidden. y, which has brought us o brought us the quantum matter has become a very perimental 2,000 physics to create conditions. Where would Graphite ystems of two-dimensional for semiconductor chers go one step further y changing the boundary n a judicious manner veries in such untrodden 1,500 Moment (e.m.u. cm– The discovery of a superconductor is always exciting, but particularly so when the material is a common stationery item and the superconductivity is possibly unconventional. FC –2 006) 0 2 4 6 8 10 Temperature (K) 12 0 5 Superconducting!! d 100 2.5 80 2.0 吃鈣的鉛筆, 1.5 超導! 60 Field (kOe) Resistivity (µΩ cm) c 10 Temp 40 1.0 C6Yb 20 0.5 0 0.0 0 20 40 60 80 Temperature (K) 100 2 3 4 Temp 25 0 Moment (e.m. Moment (e.m. –4 –6 –0.04 FC –0.06 C Yb –8 –0.08 Diamagnetic Response 6 –10 –12 –0.10 ZFC 0 2 4 6 8 10 Temperature (K) –0.12 12 C6Ca ZFC 0 5 10 15 20 Temperature (K) 25 漢賊不兩立 — 不喜歡磁場的超導體 bc d HC1 || ab 0.00 80 –0.02 2.0 FC 60 –0.04 1.5 –0.06 40 –0.08 20 –0.10 –0.12 0 0 0 12 2.5 06) d 2.5 6Ca C6CYb ZFC 25 205 4010 6015 8020 100 Temperature(K)(K) Temperature Field (kOe) Resistivity (µΩ cm cm)–3) Moment (e.m.u. 0.02 100 HC2 || ab HC1 || c HC2 || c 1.0 C6Yb 0.5 0.0 2 3 4 5 6 7 Temperature (K) 8 26 Where are the electrons? LETTERS Mb Ca Ma Ca 2,000 Graphite (002) C6Yb (004) 作媒的電子雲 1,500 nts) Graphite (004) 27 你了解 電子的自旋嗎? Charge and Spin 電荷︰運用半導體 處理資訊 自旋︰運用磁性材料 儲存資訊 29 What is “spintronics” ? Spintronics = Spin + Electronics 如何在複雜的凝態系統中, 隨心所欲地操控自旋。 30 Spin Valve G. Prinz, Science 282, 1661 (1998) 自旋不同,物性不同。 metal insulator 31 Spin Valve 用自旋來當開關。 32 Moving Electric Field... 複習一下電磁學… 1 ∂E ∇ × B = µ0 J + 2 c ∂t ∇ 電動生磁 1 ! −µ v × E ×BB== J + c2 0 1 ! B =− 2 c 1 ∂E c2 ∂t v×E 33 Rashba Interaction 自旋–軌道 交互作用 34 Datta-Das Transistor 用電場來控制自旋 用自旋來控制電流 35 (Ga,Mn) As 半導體摻點磁性 雜質,如何? 36 Ferromagnetic Semiconductor 於是,磁性半導體 就誕生了。 37 Curie Temperature Hso = αR (k × n̂) · = Ωk · S Curie 溫度與電洞密 度1/3次方成正比。 1/3 Tc ∼ nh 38 Field Effect ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) 33345)61''-7"8,1#09):1709-,.%9#-'$) 1#1'-$#'%9#%'1$) 08+#40''".0"#0-,) "22=)'1.%91.)D=) +1).-7"0,)?"22) FO"(!,IA$) D=) "2$-) -D$1'E1.) VG < 0 0.04 0.02 RHall (k$ ) 1 1.5 K 5K 10 K 0 20 K -1 R Hall (k$) +1)'1"$-,)?+=) =) -,2=) ") $208+#) .'"7"#09)1>>19#@) )0$)-D$1'E1.)0,) M","7%'")1#)"2@) ) 2-?1') B+-#-,) A$)9"$1@)*,)#+1) 0-,) 1>>19#$) 0,) 1.)#-)#+1)$7"22) -0.5 0.00 0.0 VG > 0 0.5 B (T) 22.5 K VG 0V +125 V -125 V 0V -0.02 -0.04 -1.0 -0.5 0.0 0.5 1.0 B (mT) Fig. 38.) V"22) '1$0$#",91) RV"22) ->) ",) 0,$%2"#1.) 8"#1) F3,(!,IA$) >012.41>>19#)#'",$0$#-')"#)KK@<)M)"$)")>%,9#0-,) ->)#+1) 7"8,1#09) >012.) >-') #+'11) .0>>1'1,#) 8"#1) E-2#"81$@) RV"22) 0$) B'-B-'#0-,"2) #-) #+1)7"8,1#0C"#0-,)->)#+1)F3,(!,IA$)9+",,12@)cBB1')'08+#)0,$1#) $+-?$) #+1) #17B1'"#%'1) .1B1,.1,91) ->) RV"22@) \1>#) 0,$1#) $+-?$) 用電場可以讓磁性消失或存在 39 Transport and Magnetism REVIEW ARTICLE cular, k agnetism ty of allows ally. omagnetism netically T 3/2 dependence expected for a homogeneous ferromagnet Magnetization (e.m.u. cm–3) 30 25 20 15 10 5 磁性與電阻有很強的 關連性,為什麼? 0 8 Resistivity (mΩ cm) key umerous f py40,41, d.c. re45,46 and thorough sible ush TC still e include the free ing in ectiveness rom certain, magnetism ns, rials Figure 2 The temperature dependence of the magnetization and resistivity of Ga0.083Mn0.917As (ref. 36). The two curves in each are for non-annealed (as grown) and annealed samples, and they reveal the striking physical changes wrought by annealing (increased TC and conductivity, and conventional behaviour of the temperature-dependent magnetization). 35 7 As-grown 6 Two-hour anneal 5 4 3 2 0 50 100 150 Temperature (K) Mn ion. The valence-band hole will then tend to align 40 Magnetism vs Optics 這下子,磁性和光學性質也扯在一起了 41 Carrier-Mediated Ferromagnetism 老師不在, 亂亂亂… 一位好老師, 幾個好學生。 一群好老師, 春風化雨。 42 你了解 奈米傳輸嗎? Quantum Wire 需要量子線來連接 奈米元件 水管流量和截 面積成正比, 那量子線呢? 44 Nano MRT I 量子線的傳導與截面積 並不成正比,而有量子 化現象。 量子線的傳導像捷運系 統一般,分成淡水線、 板南線、木柵線等等。 45 Nano MRT II 每一條捷運線標誌不同 46 Nano MRT III 破壞一下,哪條捷運線斷掉了? 47 DNA Nanowire? 連 DNA 都可以拿 來當電線 • 導體 ? • 絕緣體 ? • 半導體 ? • 超導體? 48 Share Solve Find the the Problem Problem Solution Thank You!!