Gerd Bergmann, physicist who probed the wavy motions of electrons
Gerd Bergmann, Professor Emeritus of Physics and Astronomy at the USC Dornsife College of Letters, Arts and Sciences, spent his career investigating materials in which electrons often misbehave.
Bergmann, who died in February at the age of 86, is best known for discovering the quantum phenomenon of “weak localization,” which occurs in very fine films like those used to build microchips. Imperfections in these slim materials, sometimes just a few atoms thick, can cause electrons to become trapped in loops rather than flow smoothly, he revealed.
“He was a dedicated mentor and valued colleague, known for his sharp intellect and passion for physics,” wrote Stephan Haas, chair of the Department of Physics and Astronomy and professor of physics and astronomy. “He will be deeply missed by the scientific community, his colleagues and the many students he inspired.”
Born in Germany in 1938, Bergmann excelled at mathematics as a teen. Later, as an undergraduate, he discovered an aptitude for physics and went on to complete a PhD at the University of Göttigen in 1965. From 1970 to 1985, he was a researcher at the prestigious Forschungszentrum Jülich research institute. He was also a professor at the University of Cologne from 1973 to 1985.
In 1984, his review on weak localization published in Physics Reports garnered Bergmann international attention in the physics world. Recruiting offers from numerous universities, including Columbia University and USC, followed. Southern California’s sunny climate, where he could indulge his hobbies of sailing and swimming, ultimately won him over. He joined the Department of Physics and Astronomy in 1986 and remained an active researcher and teacher at USC for nearly four decades.
Along with his investigation of thin films, Bergmann researched electron behavior within metals. In a series of experiments published in the early 2000s, he revealed that cesium, a soft, silvery, alkali metal often thought of as “simple,” could dramatically amplify the magnetism of iron and cobalt atoms deposited on its surface. These effects suggested that cesium might hold a key to rethinking how electrons interact in metals.
Later in his career, he focused on the theoretical study of the Kondo Cloud, a quantum phenomenon where a tiny magnetic impurity in a material is screened by surrounding electrons. Using mathematical models he developed, Bergmann probed how far this “cloud” of electrons extends around the impurity.
“He was one of the very few physicists I’ve known who could do both theory and experiments,” says Grace Lu, professor of physics and astronomy, electrical engineering and material science at USC Dornsife and USC Viterbi School of Engineering. The two first met in 2000. Bergmann and Werner Däppen, Professor Emeritus of Physics and Astronomy and then department chair, picked Lu up from the airport when she arrived to give a seminar at USC before joining the university. It was the sort of above-and-beyond gesture that exemplified his devotion to his field and his colleagues.
Bergmann, a Fellow of the American Physical Society and recipient of the Physics Prize of the Academy of Göttingen, would correct others on physics concepts, says Lu. “But, he wasn’t trying to show off; he just wanted to make sure that others understood.”
For his undergraduate courses, Bergmann hand wrote all of his lecture notes and then rewrote them each semester. He felt it was the best way to retain the material, says Lu, who inherited those many years of notes.
For alumnus Douglas Garrett, Bergmann was instrumental in reshaping the course of his career. A year after graduating from the USC Thornton School of Music with a bachelor’s degree in music composition, Garrett was feeling a bit adrift while working at Tower Records in Hollywood. Hunting for a better career plan, Garrett remembered how much he’d enjoyed a physics class he’d taken with Bergmann in order to satisfy a science requirement for his major.
“I was that student that went to every office hour with question after question, and I think he appreciated that,” says Garrett. “This is likely why, when I randomly called him a year later and told him I was considering studying physics, he immediately offered me a job in his lab. This put me on a path that I’m still on 30 years later. ”
Garrett completed a second bachelor’s degree in physics in 1999, followed by a PhD in 2008, both from USC Dornsife. He’s now vice-president of research and development at iSpotTv, where he leads AI initiatives. “Dr. Bergmann was incredibly rigorous but deeply creative at the same time. I will miss our discussions that we used to have daily, even hourly,” he says. “He changed my life.”