USO Unidentified Superconducting Object

USO Unidentified Superconducting Object www.phwiki.com

USO Unidentified Superconducting Object

Swanson, Tim, Film Editor has reference to this Academic Journal, PHwiki organized this Journal 101 years of superconductivity Kazimierz Conder Laboratory as long as Developments in addition to Methods, Paul Scherrer Institute, 5232 Villigen PSI, Switzerl in addition to kazimierz.conder@psi.ch Electrical resistivity at low temperatures Kelvin: Electrons will be frozen – resistivity grows till . Dewar: the lattice will be frozen – the electrons will not be scattered. Resistivity wiil decrese till 0. Matthiesen: Residual resistivity because of contamination in addition to lattice defects. Resistivity at low temperatures- pure mercury (could repeatedly distilled producing very pure samples). Repeated resistivity measurements indicated zero resistance at the liquid-helium temperatures. Short circuit was assumed! During one repetitive experimental run, a young technician fall asleep. The helium pressure (kept below atmospheric one) slowly rose in addition to , there as long as e, the boiling temperature. As it passed above 4.2 K, suddenly resistance appeared. From: Rudolf de Bruyn Ouboter, “Heike Kamerlingh Onnes’s Discovery of Superconductivity”, Scientific American March 1997 Hg TC=4.2K 1895 William Ramsay in Engl in addition to discovered helium on the earth 1908 H. Kamerlingh Onnes liquefied helium (boiling point 4.22 K) Superconductivity- discovery I

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Superconductivity- discovery II Liquid Helium (4K) (1908). Boiling point 4.22K. Superconductivity in Hg TC=4.2K (1911) Further discoveries 1986 (January): High Temperature Superconductivity (LaBa)2 CuO4 TC=35K K.A. Müller und G. Bednorz (IBM Rüschlikon) (Nobel preis 1987) 1987 (January): YBa2Cu3O7-x TC=93K 1987 (December): Bi-Sr-Ca-Cu-O TC=110K, 1988 (January): Tl-Ba-Ca-Cu-O TC=125K 1993: Hg-Ba-Ca-Cu-O TC=133K (A. Schilling, H. Ott, ETH Zürich) 1911-1986: “Low temperature superconductors” Highest TC=23K as long as Nb3Ge

The current can flow 100 000 years!! Zero resistivity Low temperatures: LN2 -1960C (77K) A superconductor is a perfect diamagnet. Superconducting material expels magnetic flux from the interior. W. Meissner, R. Ochsenfeld (1933) On the surface of a superconductor (T

Perovskite ABX3 X=O2-, F-, Cl-) A=alkali, alkali-earth in addition to rare-earth metals, B=transition metals (also Si, Al, Ge, Ga, Bi, Pb ) Perovskite is named as long as a Russian mineralogist, Count Lev Aleksevich von Perovski. The mineral (CaTiO3) was discovered in addition to named by Gustav Rose in 1839 from samples found in the Ural Mountains. X A B (LaBa)2 CuO4 TC=35K K.A. Müller und G. Bednorz (IBM Rüschlikon 1986 ) High Temperature Superconductor. La2-xSrxCuO4 CuO2 –layer 5-fold Cu coordination CuO-chain 4-fold Cu coordination BaO Y Perovskite “YBa2Cu3O9” High Temperature Superconductor: YBa2Cu3O7-x

Oxygen doping in YBa2Cu3O7-x TC Layered structure of YBa2Cu3O7-x Conducting CuO2 layers Charge reservoir holes electrons holes 2Cu2+ + 0.5O2 2Cu3+ +O2- 2CuxCu + V O +0.5O2 2CuCu + OxO 2CuCu 2CuxCu + 2h Y BaO CuO CuO2 Conducting CuO2 layers YBa2Cu3O7 TC=93 ab [Å] c [Å] ab [Å] c [Å] 1500 6000 15 4 8.3Å 3.4Å Bi2Sr2Ca2 Cu3O10 TC=110 ab [Å] c [Å] ab [Å] c [Å] 2000 10 000 13 2 Cooper-pairs can not tunnel through the charge reservoir! For YBa2Cu3O7 single crystals at 4.2K jc(ab)~107A/cm2, jc(c)~105A/cm2 Unit cell Layered structure of YBa2Cu3O7-x. Anisotropy

Summary History of discovery in addition to farther development How it works (still open problem as long as HTc) What are the materials Potential applications A spin of a Cooper pair is: Most of the HTc superconductors are: Superconductors type II in comparison to type I: In the BCS theory it is assumed that the interaction between electrons in Cooper pairs is mediated by: Vortex phase is observed: Isotope effect (Tc dependence on lattice mass) is: In case of many High Temperature superconductors in order to achieve temperatures below Tc one can use:

Swanson, Tim Film Editor

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