He Turned Up The Heat On a Very Cold Subject

Today's Innovators

Murray Hill, N.J. (June, 1997) -- Bertram Batlogg looks up at pictures mounted high on his office walls of the mountains surrounding Bludenz, the small Austrian city where he grew up. Then he says somewhat wistfully, "Every mountain has its own character, distinct shape, distinct color, and there is a distinct way to climb it."

The Bell Labs physicist and world-renowned superconductivity expert then lifts a framed picture of a germanium copper oxide crystal that had been perched atop a cabinet and says, "It's the same way with these materials. Each and every material has its own character. The way we deal with it, the way it functions, and the way we have to think about it."

"These materials, particularly if they are grown in the form of crystals...are aesthetically appealing. They have shiny surfaces, they have special shapes, corners, and very often great colors. Look at these blue colored crystals," he continues pointing to the picture as though it were a great work of art. "I find it most pleasing."

There are also striking similarities between his love of the challenges of mountain climbing and skiing and the fulfillment Batlogg clearly derives from his striving to master these crystals by coaxing them to reveal the secrets of their superconductive characteristics.

What makes these crystals, and certain other materials, superconductive is their ability to lose all electrical resistance when cooled to below their critical temperatures. And while rapid fire advancements have caused these temperatures to rise quickly over the past several years, they are still cold enough to make the winter temperatures on Batlogg's beloved mountain peaks seem like the tropics.

When he came to Bell Labs in 1979 as a post doctoral fellow from the Swiss Federal Institute of Technology in Zurich, Batlogg planned to stay a year or two and return to his homeland.

"Less than a year passed and my department head came into my lab and casually asked if I wanted to stay a little bit longer," he says.

It was a difficult decision, because he was anxious to get back to Austria, but after consulting with his family, he decided to stay. That was 18 years ago. "I got used to not having the mountains in front of my office windows any more," he said. These days he skis the Rockies more often than the Alps.

Seven years after joining Bell Labs, Batlogg was named head of the Solid State and Physics of Materials Research Department. The year was 1986 and all was relatively quiet in the small, esoteric world of superconducting science. But then, near the end of that year, an announcement was made that was the superconducting equivalent of a sonic boom.

77-Degree Barrier

A material was discovered that would soon lead to the breaking of what Batlogg called, "the famous 77-degree barrier." Seventy-seven degrees Kelvin (K), or -320° F, is the point at which nitrogen, the primary constituent of air, becomes a cryogenic liquid. In the world of superconductivity that had been downright hot. Prior to the breaking of that barrier the materials known to be superconducting had to be chilled down to 23K (-418° F), or close to absolute zero. To achieve that temperature required the use of rare and precious liquid helium. Liquid nitrogen, on the other hand, is plentiful and relatively inexpensive.

[ Bertram Batlogg in the lab ]

A plume of vapor rises as Bertram Batlogg prepares to fire up a superconducting magnet by piping in liquid helium at -452° F.

The breakthrough that led to the shattering of the 77-degree barrier was made by two scientists working at an IBM laboratory near Zurich, who Batlogg knew from his college days. Their discovery that copper oxide materials could become superconductive at unprecedentedly high temperatures gave birth to the field known as "high temperature superconductivity," or High Tc for short.

"We were hovering around 23 degrees for many years, then came this family of copper oxide materials," said Batlogg. "It began a worldwide revolution in the field."

At Bell Labs, Batlogg and Bob Cava, another superconductivity expert, and their colleagues immediately began investigating copper oxides. "In no time we defined a better material than originally reported. This gave us a really flying start," said Batlogg.

Advances at Bell Labs and elsewhere came in rapid succession. Within a few months new copper oxide materials were developed that had transition temperatures well above 77K.

"Nowadays copper oxide is superconducting at around 160 degrees Kelvin [-168° F], which is halfway up to room temperature," says Batlogg, "and our part was quite significant in these discoveries."

Media Darlings

Meanwhile, the expectations for High Tc created by the copper oxide discoveries opened the floodgates to the small and sequestered world of superconductivity research. "There was an uninhibited enthusiasm," said the Bell Labs physicist, who along with Cava, was thrust into the limelight.

A NOVA television crew virtually lived with them for a week. They were also quoted extensively in articles about superconductivity appearing in Time and Life magazines, U.S. News & World Report, and the London Press, to mention a few.

Although high temperature superconductors have yet to live up to their billing during those heady days of the late 1980s, they hold great promise for fields ranging from electronics to power transmission and magnetic sensing.

With superconductivity electric utilities could transmit power more efficiently; electronic equipment could be smaller and higher performing; and large magnets can be made extremely powerful and efficient.

One of the most widespread practical applications of such supercooled magnets is in magnetic resonance imaging (MRI) machines used in the medical field to view internal organs without the risks of X-rays.

Work at Bell Labs dating back to the 1960s was instrumental in the successful scientific and engineering development of superconducting technology. " Bell Labs has a splendid history of making major discoveries in the field of superconductivity," says Batlogg. Much of the early work was done by Bernd Matthias, who "was a world leading expert in developing new materials, always with the quest of finding those that would be superconducting at higher and higher temperatures....he was one of our Bell Labs heroes."

In fact, the International Conference on Materials and Mechanism of Superconductivity created a Bernd Matthias Prize which this year was bestowed on Batlogg and Cava, for their "leading work in a variety of superconductors."

'One-Two-Three'

One of their most important contributions was the discovery of precisely what it is that imparts High Tc characteristics to the copper oxide material first found to have that capability. Until then it was only known that copper oxides were High Tc materials, but not what combination of elements made them such.

"We came up with the right recipe," says Batlogg. It was a formula that came to be known as the 'one-two-three' compound...for one barium, two yttriums, three coppers, and seven oxygens."

This discovery came at a time when the excitement over High Tc led to an intensity of work that Batlogg says was amazing. "We would spend shifts here, working day and night."

Being well aware of the need to quickly publish their one-two-three findings Batlogg and his colleagues prepared a patent application in a day, and decided to write a paper on the subject that same night.

"We sat down around 10 o'clock. I called my wife, she delivered two bottles of hot coffee, probably the strongest coffee I've ever had, and a fresh sheet of corn bread," said Batlogg, who lives within walking distance of his office. "The next time we turned around it was 6 a.m. The paper was written, and the coffee was gone, but we were alive and ready to go to the lab -- apparently the coffee did its job."

The resulting paper was published in Physical Review Letters.

During this period the Bell Labs scientists also began to focus on the applicability of superconductivity to telecommunications, and determined that microwave transmissions presented an opportunity. Microwave filters using this technology have since been developed and are now being tested.

Room Temperature

In another field, Batlogg is working on the development of organic semiconductors while continuing to investigate classes of materials similar to copper oxide that hold promise for yet higher temperature superconductivity. The goal of the superconductivity work is to develop a "general understanding of how the materials function, what makes them function the way they do, and to learn how to prepare them and manipulate them in a way this is beneficial for practical applications" explains Batlogg.

And never far from his mind is the thought of finding a material that is superconducting at room temperature or above. That, says Batlogg, undoubtedly reminiscing about the 77- degree-barrier days, "would capture the imagination."

As for if and when that may happen, the physicist alludes to a mountain climbing dictum as he says, "You can never predict breakthroughs. But you better be ready when they occur."