UBC physicists develop 'impossible' technique to study and develop superconductors

June 24, 2008

A team of University of British Columbia researchers has developed a technique that controls the number of electrons on the surface of high-temperature superconductors, a procedure considered impossible for the past two decades.

Led by Physics Assoc. Prof. Andrea Damascelli, the team deposited potassium atoms onto the surface of a piece of superconducting copper oxide. The approach allows the scientists to continuously manipulate the number of electrons on ultra-thin layers of material.

The details are published this week in the prestigious journal Nature Physics.

Superconductivity - the phenomenon of conducting electricity with no resistance - occurs in some materials at very low temperatures. High-temperature superconductors are a class of materials capable of conducting electricity with little or no resistance in temperatures as high as -140 degrees Celsius.

"The development of future electronics, such as quantum computer chips, hinges on extremely thin layers of material," says Damascelli, Canada Research Chair in the Electronic Structure of Solids.

"Extremely thin layers and surfaces of superconducting materials take on very different properties from the rest of the material. Electrons have been observed to re-arrange, making it impossible for scientists to study," says Damascelli. "It's become clear in recent years that this phenomenon is both the challenge and key to making great strides in superconductor research.

"The new technique opens the door to systematic studies not just of high-temperature superconductors, but many other materials where surfaces and interfaces control the physical properties," says Damascelli. "The control of surfaces and interfaces plays a vital role in the development of applications such as fuel cells and lossless power lines, and may lead to new materials altogether."

The superconductors Damascelli's team experimented on are the purest samples currently available and were produced at UBC by physicists Doug Bonn, Ruixing Liang and Walter Hardy.

Part of the study was carried out at the Advanced Light Source synchrotron in California. In the future, the design and study of novel complex materials for next-generation technologies will be carried out at the Quantum Materials Spectroscopy Center currently under construction at the Canadian Light Source in Saskatoon under Damascelli's leadership.

University of British Columbia

---

---

	Superconductivity: A Very Short Introduction by Stephen J. Blundell (Author) Superconductivity--the flow of electric current without resistance in certain materials as temperatures near absolute zero--is one of the greatest discoveries of 20th century physics, but it can seem impenetrable to those who lack a solid scientific background. Outlining the fascinating history of how superconductivity was discovered, and the race to understand its many mysterious and counter-intuitive phenomena, Stephen Blundell explains in accessible terms the theories that have been developed to explain it, and how they have influenced other areas of science, including the Higgs boson of particle physics and ideas about the early Universe. This Very Short Introduction examines the many strange phenomena observed in superconducting materials, the latest developments in high-temperature...
	Introduction to Superconductivity: Second Edition (Dover Books on Physics) (Vol i) by Michael Tinkham (Author), Physics (Author) Accessible to graduate students and experimental physicists, this volume emphasizes physical arguments and minimizes theoretical formalism. Topics include  the Bardeen-Cooper-Schrieffer and Ginzburg-Landau theories, magnetic properties of classic type II superconductors, the Josephson effect, fluctuation effects in classic superconductors, high-temperature superconductors, and nonequilibrium superconductivity. 109 figures. 1996 edition.
	Nanostructured Superconductors by Victor V. Moshchalkov (Author), Joachim Fritzsche (Author) The main focus of the book is to present the effects of nanostructuring on superconducting critical parameters. Optimizing systematically flux and condensate confinement in various nanostructured superconductors, ranging from single nano-cells to their huge arrays, critical fields and currents can be increased up to their theoretical limits, thus drastically improving the potential for practical applications of nanostructured superconductors.
	The Breakthrough: The Race for the Superconductor by Robert M. Hazen (Author)
	Theory of Fluctuations in Superconductors (International Series of Monographs on Physics) by Anatoly Larkin (Author), Andrei Varlamov (Author) This book presents a complete encyclopaedia of superconducting fluctuations, summarising the last thirty-five years of work in the field. The first part of the book is devoted to an extended discussion of the Ginzburg-Landau phenomenology of fluctuations in its thermodynamical and time-dependent versions and its various applications. The second part deals with microscopic justification of the Ginzburg-Landau approach and presents the diagrammatic theory of fluctuations. The third part is devoted to a less-detailed review of the manifestation of fluctuations in observables: diamagnetism, magnetoconductivity, various tunneling characteristics, thermoelectricity, and NMR relaxation. The final chapters turn to the manifestation of fluctuations in unconventional superconducting systems:...
	Applications of High Temperature Superconductors to Electric Power Equipment by Swarn S. Kalsi (Author) The only one-stop reference to design, analysis, and manufacturing concepts for power devices utilizing HTS.High temperature superconductors (HTS) have been used for building many devices for electric grids worldwide and for large ship propulsion motors for the U.S. Navy. And yet, there has been no single source discussing theory and design issues relating to power applications of HTS—until now. This book provides design and analysis for various devices and includes examples of devices built over the last decade.Starting with a complete overview of HTS, the subsequent chapters are dedicated to specific devices: cooling and thermal insulation systems; rotating AC and DC machines; transformers; fault current limiters; power cables; and Maglev transport. As applicable, each chapter...
	Superconductor/Semiconductor Junctions (Springer Tracts in Modern Physics) by Thomas Schäpers (Author) This book, featuring the most comprehensive treatment of Josephson junctions ever published, describes superconductor/two-dimensional-electron-gas (2DEG) structures, providing a better understanding of their transport properties. It also discusses the control of junctions using gate electrodes or injection currents, and the physical effects observed in these junctions.
	Non-Centrosymmetric Superconductors: Introduction and Overview (Lecture Notes in Physics) by Ernst Bauer (Editor), Manfred Sigrist (Editor) Superconductivity in materials without inversion symmetry in the respective crystal structures occurs in the presence of antisymmetric spin-orbit coupling as a consequence of an emerging electric field gradient. The superconducting condensate is then a superposition of spin-singlet and spin-triplet Cooper pairs. This scenario accounts for various experimental findings such as nodes in the superconducting gap or extremely large upper critical magnetic fields. Spin-triplet pairing can occur in non-centrosymmetric superconductors in spite of Anderson’s theorem that spin-triplet pairing requires a crystal structure that exhibits inversion symmetry. This book, authored and edited by leading researchers in the field, is both an introduction to and overview on this exciting branch of novel...
	Neutron Scattering in Layered Copper-Oxide Superconductors (Physics and Chemistry of Materials with Low-Dimensional Structures) by Albert Furrer (Editor) This is the first book which reviews the most important results obtained in the past decade for layered copper-oxide high-temperature superconductors by neutron scattering techniques. The following topics are thoroughly introduced, methodically discussed and highlighted with the most important results by acknowledged experts in their respective fields: static and dynamical properties of the crystal lattice (oxygen site occupation, charge transfer, charge-stripe order, phonon dispersions and density-of-states), static and dynamical magnetic correlations (phase diagrams, 2D and 3D magnetic ordering, spin waves and spin fluctuations, crystal-field excitations) and the structure of the flux-line lattice (field and temperature dependence). The 2D features of the copper-oxide...
	High-Temperature Cuprate Superconductors: Experiment, Theory, and Applications (Springer Series in Solid-State Sciences) by Nikolay Plakida (Author) High-Temperature Cuprate Superconductors provides an up-to-date and comprehensive review of the properties of these fascinating materials. The essential properties of high-temperature cuprate superconductors are reviewed on the background of their theoretical interpretation. The experimental results for structural, magnetic, thermal, electric, optical and lattice properties of various cuprate superconductors are presented with respect to relevant theoretical models. A critical comparison of various theoretical models involving strong electron correlations, antiferromagnetic spin fluctuations, phonons and excitons provides a background for understanding of the mechanism of high-temperature superconductivity. Recent achievements in their applications are also reviewed. A large number of...