You've arrived at the homepage of the UBC Superconductivity Group. We're researchers in the Department of Physics and Astronomy at the University of British Columbia who have a common interest in superconductivity, particularly high-temperature superconductors.

If you are looking for an introduction to our group, a little information on superconductivity, or if you just stumbled here by accident while websurfing, then this is a good place to start.

If you have visited us before, already know who we are, and already know about superconductivity, then you may want to skip this page and go back to our superconductivity home page. You will find links there that give you much more detail on the people in our group (and how to contact them) and some of our current research activities. You'll also find a collection of some of our papers, sets of data, and links to a variety of useful sites.

Superconductivity is both an old and a new field of research. This phenomenon, where metals undergo a transition to a state of zero electrical resistance, was first discovered in 1911, shortly after Kammerlingh-Onnes first produced liquid helium. The superconducting state of matter has fascinated scientists for decades with its strange properties and puzzling origins. The properties of superconductors were so unexpected that it took decades to explore the many phenomena that they exhibit and it wasn't until 1957 that a satisfactory explanation was produced by Bardeen, Cooper and Schrieffer.

Over these decades and through to the 1970's many elements and compounds were found to be superconducting, with one of the goals being to produce materials with higher superconducting transition temperatures. This was a driving force because the need to use liquid helium to access the low temperatures required for a metal to become a superconductor stood in the way of many possible applications of these materials. The exception to this roadblock has been the development of superconducting electromagnets, used both in research and in magnetic resonance imaging (MRI). For a period of time the quest to find superconductors with higher critical temperatures appeared to languish, but in 1986, Bednörz and Müller threw the field wide open again when they discovered a family of copper oxide compounds with high superconducting transition temperatures. Their discovery was quickly followed by the discovery of YBa₂Cu₃O_7-x, a compound that becomes superconducting at 93 Kelvin, a temperature well above the boiling point of nitrogen (77 Kelvin).

Since 1987, these new high temperature superconductors have become one of the dominant topics of research in condensed matter physics. For many, the lure of possible applications of these new materials is driving a lively push towards exploiting the availability of superconductivity at liquid nitrogen temperatures ("high temperature" by a condensed matter physicists's standards). Others continue the quest to find members of the family with ever higher superconducting transition temperatures (the present record is around 135 Kelvin, almost halfway to room temperature). For many of us, the real lure is that this is one of the great unsolved problems in all of physics. Despite our deep understanding of conventional superconductors and the huge number of scientists who have been working on this problem, we still don't really understand how high temperature superconductors work. In fact it seems very much like the situation that Kamerlingh-Onnes and his contemporaries faced decades ago; we have a state of matter that is in many ways different from anything that our field of research has had to tackle before.

Here at the the University of British Columbia, we have a large number of people engaged in a wide range of research into superconductivity. There has long been a strong effort at UBC Vancouver in research into the physics of metals. With the discovery of high temperature superconductivity, a great deal of effort shifted toward these new materials. The unique techniques available in the muon spin resonance group at the nearby TRIUMF cyclotron were quickly brought to bear on the new materials and this research, spearheaded by Rob Kiefl and Jess Brewer, led to the realization that a strong effort in developing new materials was needed at UBC. Walter Hardy and Jim Carolan began piecing together the elements required to push ahead into this field and the group has grown to include research in crystal growth, film growth, superconductor applications, and a wide range of physical measurements, in particular microwave surface impedance and magnetic measurements. UBC's success in this endeavour is based on a strong emphasis on control of the materials, particularly through the efforts of Ruixing Liang, who is both a solid state chemist and a physicist. Our crystal growth and other research have spawned collaborations with many groups worldwide. We are also associated with the Canadian Institute for Advanced Research, an organization which promotes collaboration among Canadian researchers. Elsewhere at this website you can find more details on the people in the group and the research that we are currently involved in.

This research is part of a broader range of study into something called "correlated metals", or more simply, exotic metals. Much of our present understanding of how ordinary metals, semiconductors, and insulators work is based upon the assumption that we can pretty much ignore the effects that electrons have on each other in a solid. Remarkably, it is possible to understand many properties of materials by considering the behaviour of a single independent electron moving through a lattice of ions. The reason that aluminum is a metal, silicon is a semiconductor, and carbon is an insulator can be understood by solving this problem. However, there are many exceptions to this simplified view of solids and as we discover new, exotic materials that cannot be explained with a "single electron model", we are forced to face the difficult problem of how to understand a solid whose properties are dominated by the interactions between electrons. High temperature superconductors are the latest, and in some ways most spectacular, example of materials that we have a hard time understanding with single electron theories. Much of the excitement over high temperature superconductors is due to the fact that they exhibit unexplained properties, even in their "normal" (non-superconducting) state, and we suspect that understanding these properties will require much better approaches to the problem of interacting electrons. In various ways, the experimental physicists studying superconductors in our department are searching for clues to the solution to this problem and some of the theorists in our department are engaged in research into how to understand the exotic properties of the recently discovered materials.