三、超导电性 ©1895：空气被液化-192℃ (81K) ©1898：氢气被液化 -253℃ (20K) ©1908：氨气被液化 4.25K K.0nnes教授(1853-1926年) 荷兰莱登实验室： ©1913年获诺贝尔物理学奖(60岁) ©29岁：莱登大学教授 ©30岁：阿姆斯特丹皇家科 学院院士 ,“绝对零度先生
J1895：空气被液化 -192℃ （81K） J1898：氢气被液化 -253℃ （20K） J1908：氦气被液化 4.25K K. Onnes教授(1853-1926年) 荷兰莱登实验室: J1913年获诺贝尔物理学奖（60岁） J29岁：莱登大学教授 J30岁：阿姆斯特丹皇家科 学院院士 J“绝对零度先生” 三、超导电性
二)廿世纪的重要发现一超导电性 0,15 Mercury superconducting Perfect conductor transition 0.10P AZ给阳 略4 re3e在npe siatel! 005 P=0 Rs105R T6=4.2K I>105 yrs dI /dt 4.1 42 4.3 4.4 Temperatyre (K) K.Omnes,Commun.Phys.Lab.(1911) ·1911年，Hg在4.2K下，电阻率完全消失 PDF created with pdfFactory Pro trial version ww.pdffactory.com
• 1911年，Hg在4.2K下，电阻率完全消失 K. Omnes, Commun. Phys. Lab. (1911). Perfect conductor 10 yrs dI dt I ρ 0 5 > = 二）廿世纪的重要发现──超导电性
抗磁性 A superconductor can pin a magnet in free space was first characterized by Meissner and Ochsenfeld in 1933.This phenomenom is now known as the "Meissner effect." Meissner effect There are TWO distinct properties. They have ZERO resistance They exhibit DIAMAGNETISM PDF created with pdfFactory Pro trial version ww.pdffactory.com
抗磁性 Meissner effect T > T c B = 0 T < T c There are TWO distinct properties. • They have ZERO resistance • They exhibit DIAMAGNETISM A superconductor can pin a magnet in free space was first characterized by Meissner and Ochsenfeld in 1933. This phenomenom is now known as the “Meissner effect
Magnetic field H destroys s/c Hc Normal State Superconducting State H<H。 H>H Tc T Current Density,J Electric current Je Superconducting Region destroys s/c B Temperature,T P≠0 Te Hc Magnetic Field,H PDF created with pdfFactory Pro trial version ww.pdffactory.com
Magnetic field destroys s/c H H c H > H c < r¹0 Ic Bc Electric current destroys s/c Normal State Superconducting State T Hc Tc H
Theories of Superconductivity ·London Equation j A 4π2 H ne为 V2B=B/22 Ginzburg-Landau Theory .e号·+)+ a)=aTT 1/2 T。 ξ(r)= 方2 2m la (T) 4πla(2 71/2 俨P=a() mc 2B B B λ(T)= 4π(2e)laTy 1 Ψ+a平+BΨ2平=0 K= GL parameter c B=heΨvΨ-平vΨ]-4e2ΨA K<1/2 type 4元 名 mc K>1/√2 type IⅡ PDF created with pdfFactory Pro trial version ww.pdffactory.com
• London Equation H x H e λ - • Ginzburg-Landau Theory ( ) ( ) ( ) [ ] A mc 4 e m i e B 4 c j A 0 c 2 e 2 m i 1 4 T , H T T T T T 8 H A c 2 e i 2 m 1 2 F F 2 2 * * s 2 1 / 2 2 c 2 c c 0 2 2 2 4 n r r h r h r r h Ñ ´ = Y Ñ Y - Y Ñ Y - Y p º ÷ Y + a Y + b Y Y = ø ö ç è æ Ñ + ú ú û ù ê ê ë é b p a = b a Y = - a = a p ÷ Y + ø ö ç è æ Y + - Ñ + b = + a Y + ( ) ( ) ( ) ( ) ( ) 1 2 type II 1 2 type I GL parameter 4 2 e T mc T 2 m T T 1 / 2 2 2 1 / 2 2 k > ® k < ® x l k = ú ú û ù ê ê ë é p a b l = ú ú û ù ê ê ë é a x = h 三）Theories of Superconductivity 2 2 / Ñ B = B lL A c J L r r 2 4pl = -