NZ: already the world leader in a 21st Century technology

Everyone knows that metal wires heat up when electricity passes through them and there are countless uses of this phenomenon of electrical resistance - from light bulbs to stoves and ovens. But over long distances from generating site to point of use there are large resistance losses giving rise to serious energy inefficiencies. There are many other applications we can think of where electrical resistance is undesirable and in some cases zero resistance or superconductivity, is a huge advantage for us such as in magnetic resonance imaging (MRI) where it is essential for this widely used healthcare technology. Superconductivity has been known for many decades but could only be reached at extremely low temperatures of liquid helium. That's minus 270 degrees Celsius. Pretty cold and more importantly rather difficult and costly to maintain. In the 1980's the hunt was on for materials which behaved as superconductors at much higher temperatures. Industrial Research Limited (IRL) was right up there in the hunt for these materials and one of these IRL materials known as BSCCO subsequently became the leading material of a class known as High Temperature Superconductors. They're not really high temperatures - still only at minus 190 degrees Celsius or around liquid nitrogen temperature but an awful lot warmer and more accessible than at liquid helium temperatures. In 1991 IRL licensed its BSCCO technology exclusively to American Superconductor Inc of the USA. And thank goodness they did. A huge battle began between multinational competitors over the patent rights to BSCCO, still the preferred material for HTS wire. A battle perhaps settled only in late 2006 after countless millions was spent in legal costs by all parties in courts around the world..

But the search immediately began for improved HTS materials for second-generation (2G) wire and there was a danger that New Zealand would not maintain its position in the race led by multinational companies which sensed an important opportunity. BSCCO is hard to make and to stabilise consistently and to turn into wire so its replacement was always on the cards. "It was hit and miss research" says the Professor Jeff Tallon, IRL's team leader of the HTS research team. "We simply did not understand the physics underlying superconductivity and the materials we were trying to optimise into superconducting wires". American Superconductor was focussed on wire making which has turned out to be the bottleneck in the whole development pathway. And so in 1999 Jeff applied to the Marsden Fund for the first of a series of three grants to understand the basic science behind superconductivity and he also won a James Cook Fellowship. What followed between 2000 and 2006 were a number of revelations and surprises which have put a field of New Zealand science well and truly into a position of world leadership and underpinning two businesses in New Zealand with the potential for more in this exciting 21st Century technology opportunity.

The first project funded by the Marsden Fund addressed the complicated phase diagram of the over 50 existing HTS materials. This work was expected to provide information about the structures and composition of the various materials as their added impurities are altered and how their physics behaves with changes in temperature. This work pointed to a second study of hybrid organic/inorganic materials, their magnetic and non-magnetic impurity atoms and their physics. The most recent project focussed on the widely accepted notion that superconducting materials are all electrically inhomogeneous, the electrons are disordered and that the superconductor physics of them arises from this. Indeed, just how do these fascinating materials work?

The research involved making use of leading edge materials science and very specialised instrumentation including tunnelling spectroscopy, some of which is only available outside of New Zealand. Professor Tallon, now in a joint partnership with Victoria University made good use of a James Cook Fellowship in establishing the collaborations needed to bring together the international resources and skills to optimise the results from these research projects. Collaborations were needed with Cambridge University, Fudan University in Shanghai, Tsukuba University in Japan and National Taiwan University.

The results of the work, regarded internationally as outstanding, have provided some surprising insights into superconducting materials and their physics. They have led to the point where Professor Tallon and his co-investigator Dr Grant Williams claim " We have now reached the stage where we can design materials for superconductivity rather than the rather random methods of the previous approach". Designer superconductors indeed!

Results from the first project made it clear that most of the materials in which industry is interested undergo phase separation - that is, they are inherently unstable. It was this new insight which enabled the long running patent fight to be determined "finally" in IRL's favour (and to keep the royalties flowing from American Superconductor). A quantum critical point in the phase diagram (a phase transition at zero temperature) pointed to optimum performance of superconductivity. It was discovered that this critical point is universal for all high temperature superconductors, a phenomenon which surprised both the researchers and the international HTS community. This gives rise to the difficulties in finding both easy to make superconductor materials and materials which are easy to use - turning into wire and so on. Professor Tallon and his fellow scientists realised from this new understanding that if they could make a structure with layers separated by an organic spacer and including transition metals in the structure just like mille feuille pastries they could substantially improve the prospects of high temperature superconductors overcoming some of the deficiencies of traditional materials used by industry. Hence they coined the term "Filophysics" or "Filomaterials". This was the subject of the second study.

The first time Filomaterials were prepared, the researchers seemed to strike it lucky. They worked well to everyone's amazement. These materials turned out to have one dimensional objects in a second two dimensional layer. It was clear then, that low dimensional systems must be targeted for optimising high temperature superconductivity.

The third project on electrical homogeneity of HTS materials showed clearly that they are only inhomogeneous on their surfaces. The bulk of the material is very important, gives rise to the superconducting effect and is very different from the surfaces of the materials. In the optimal regions and the overdoped regions they are electrically homogeneous. This was a surprise to everyone in the HTS research community.

What of the benefits for New Zealand? The knowledge to develop the best third generation (3G) HTS materials has been developed in New Zealand. Five key patents have been filed which cover most of the results disclosed in these three projects including filings covering materials obtaining the highest superfluid density - or strength of superconductivity - at the quantum critical point and the overarching patent on the Filomaterials. This puts New Zealand technology in a very strong position as it participates in this developing industry of the 21st Century.

In 2004, a Wellington-based company HTS-110 was formed to take advantage of the New Zealand leadership in this field. As was always foreseen, the relationship with American Superconductor played a key role in its establishment but it is also underpinned by the research from the Marsden funded projects. HTS-110 began using American Superconductor's wire in HTS devices. Initially they were aimed at the research market but now the target market is industrial. Underway is a range of industrial products aimed at in-line chemical analysis to boost productivity in the petrochemical industry. They're also working on improved and more energy efficient magnets for customers ranging from synchrotron facilities, to makers of semiconductor manufacturing tools. According to HTS Chief Technical Officer Donald Pooke the Wellington company is being taken very seriously. In part this is because of the credibility of New Zealand research in the field. "The company was established on the basis that we knew more about how the wire behaves than anyone else in the world and this gave us strong direction. For example the understanding of the quantum critical point guided the tailoring of wire processing to improve performance and achieve product goals" says Donald. "Now that the 2G wires are coming available, the New Zealand knowledge, covering both doping and inhomogeneity, can be used to optimise those too, helping to further HTS product opportunities".

But there have also been some direct benefits to HTS-110 from the Marsden funded work. Employing his wide research network and collaborations Professor Tallon organised a meeting at an international conference focused on advanced materials research capabilities and out of this HTS-110 received orders for two 5 Tesla superconducting magnets one of them for the Hahn-Meitner Institute in Germany and the other for ANSTO in Sydney Australia. That's over $1.2m worth. "As a result of his work Jeff has opened doors for us. Both these orders came from Jeff's reputation and ability to attract the people in the field " says Dr Pooke.

For Professor Tallon and Dr Williams over 90 publications have come from this research. This has given Professor Tallon the highest number of publication citations of any physicist in New Zealand.

What of the future? It's very early days to see the scope of benefits from this work. It has taken over 20 years to realise the benefits of that first leadership in the BSCCO materials. But the pathway in principle is clear. We are in a strong position. The American Superconductor Corporation and large multinationals of this world are focussed on building ships engines for the largest aircraft carriers and container ships, and huge cables for carrying power supplies for the world's largest cities. They may use our technologies. But as a result of three Marsden Fund projects (and a James Cook Fellowship), New Zealand is already successfully carving a place for itself in the potentially huge but largely unknown market for smaller more manageable devices suited to the scale of our own resources. HTS-110 Limited and more recently an international wire manufacturing company with Christchurch operations has begun to develop wire products based on superconducting wires. HTS products may not be replacing our traditional home appliances yet but in New Zealand we're already leaders in this technology of the 21st Century.