John Robert Schrieffer Daniel Arovas, Greg Boebinger, and Nick Bonesteel

Citation: Physics Today 73, 1, 63 (2020); doi: 10.1063/PT.3.4395 View online: https://doi.org/10.1063/PT.3.4395 View Table of Contents: https://physicstoday.scitation.org/toc/pto/73/1 Published by the American Institute of Physics

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made when Cooper solved the problem John Robert Schrieffer of two electrons above a quiescent Fermi towering figure in theoretical con- sea. He took into account the effective at- densed-matter physics, John Robert tractive interaction mediated by phonons, ASchrieffer died on 27 July 2019 in Tal- which resulted in a bound state of elec- lahassee, Florida. He is best known for trons. Schrieffer’s focus crystallized on his crucial contributions to the theory of finding a many-electron theory that superconductivity, a problem that since could incorporate Cooper’s bound pairs, its discovery in 1911 had vexed physi- which, though not quite bosons, some- cists searching for a microscopic expla- how needed to be condensed. nation of the phenomenon. The crucial inspiration came several Born in Oak Park, Illinois, on 31 May months later, while Schrieffer was in New 1931, Schrieffer moved with his family to York City for an American Physical Soci- Eustis, Florida. At his small high school, ety (APS) meeting; during a subway ride, he was encouraged to pursue self-study he first scrawled the iconic BCS wave- ARCHIVES VISUAL SEGRÈ EMILIO AIP in mathematics and sciences. His interest function on paper. The publication in 1957 in building radios was kindled in 1944 of their revolutionary approach, known when, while babysitting, he began read- as BCS theory, was swiftly recognized as ing a copy of The Radio Amateur’s Hand- a definitive work and indeed proved sem- book. Schrieffer set his sights on studying inal. A torrent of results soon followed, which explained or were validated by nu- electrical engineering at MIT, where he John Robert Schrieffer instead became captivated by physics. merous experiments. The microscopic He completed his bachelor’s thesis under theory of superconductivity had been John Slater. solved. (Subsequent work by Philip An- fer, Wu-Pei Su, and Alan Heeger devel- Schrieffer had intended to do gradu- derson and Yoichiro Nambu would re- oped their celebrated model of poly- ate studies in nuclear physics, and he re- solve the subtle issue of gauge invari- acetylene. They found a mechanism for ceived a Fulbright scholarship to the UK ance.) The significance of BCS theory was spin–charge separation—that is, excita- to work with Léon Rosenfeld and recognized in 1972 with the Nobel Prize tions with charge but no spin or spin but Patrick Blackett. But fate intervened; be- in Physics. Schrieffer’s oral history inter- no charge, as if the electron, which is a cause of the Korean War and his father’s views with the American Institute of fundamental particle, had split into two failing health, he remained in the US. Physics (https://tinyurl.com/tklwrlx) pro- pieces. Further work by Schrieffer and Schrieffer knew of John Bardeen and vide a wonderful account of the early others explored the phenomenon of the transistor, so he was delighted to be days of BCS. fractionalization. That reified earlier offered the opportunity to study under As an NSF postdoc in fall 1957, Schrief - field theoretical models and identified him at the University of Illinois at fer went first to the University of Bir - for the first time materials, such as poly- Urbana-Champaign. Initially, Schrieffer mingham and then to the Niels Bohr acetylene and fractional quantum Hall worked on surface electron transport in Institute in Copenhagen, where he met systems, where fractional charge, spin, semiconductors, even performing exper- Anne Grete Thomsen, his future wife. and statistics are manifested by their iments in Bardeen’s laboratory. In spring After a year teaching at the University of low-energy excitations. 1955, sensing that Bardeen was gearing Chicago, Schrieffer joined the University In 1983 Schrieffer was awarded the up for another attack on superconductiv- of Illinois faculty in 1959. He was at the National Medal of Science, and he served ity, Schrieffer selected it as a thesis topic. University of Pennsylvania from 1962 as APS president in 1996. Sadly, due to Postdoctoral researcher Leon Cooper ar- to 1980, when he went to the University illness, the last 20 years of his life were rived in Urbana that fall. of California, Santa Barbara, and was the extremely difficult and indeed tragic. In the early 1950s, work by Herbert second director of its Institute for Theo- Throughout his struggles, Anne stood by Fröhlich and Bardeen independently de- retical Physics. His presence at the insti- him until her death in 2013. In addition rived an isotope effect for the critical tute and on the physics faculty con- to his brilliance—and the light in his eye temperature, but the main phenomenon tributed greatly to the university’s when he discussed physics—Bob’s kind- remained unexplained, largely because stature and to its rise to prominence in ness and avuncular nature were trea - no techniques were available to address the sciences and engineering. His final sured by his many students, colleagues, the many-body problem. By the time academic appointment, starting in 1992, and friends. Bardeen, Cooper, and Schrieffer began was as a Florida State University profes- Daniel Arovas their assault, Bardeen was convinced of sor and chief scientist of the National University of California, San Diego two important aspects: that the elec- High Magnetic Field Laboratory, where, La Jolla tronic spectrum must exhibit an energy once again, he helped establish the cre- Greg Boebinger gap, and that the many-electron wave- dentials of a major new endeavor. Nick Bonesteel function must reflect a condensation in For more than four decades, Schrief- National High Magnetic Field Laboratory momentum space, with long-range fer worked at the forefront of con- Florida State University phase coherence. A major advance was densed-matter physics. In 1979 Schrief- Tallahassee

JANUARY 2020 | PHYSICS TODAY 63