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Charles Kittel
In Memoriam

Charles Kittel

Professor of Physics, Emeritus

UC Berkeley
Charles “Charlie” Kittel, famous for his research and teaching in the field of solid-state physics (also known as condensed matter physics), passed away peacefully at his home in Berkeley on May 15, 2019, two months before his 103rd birthday.

Born in New York City on July 18, 1916, Charlie graduated from Horace Mann School for Boys, Riverdale, NYC in June 1934. He entered the Massachusetts Institute of Technology (MIT) in 1934, first as a chemistry major and then changed his major to physics. He transferred to Cambridge University in 1936 and received his B.A. there two years later. He earned his Ph.D. degree in 1941 from the University of Wisconsin–Madison, where his adviser was Gregory Breit. From 1940 to 1942, Charlie focused on problems in degaussing and magnetic mine warfare at the Naval Ordnance Laboratory. He served in the U.S. Navy as a research physicist at a British Admiralty research establishment in Scotland and as a naval attaché at the U.S. Embassy in London. He went on to work on antisubmarine warfare and operations research in Washington, D.C., and London. In 1945 he returned to MIT and took a position in the Research Laboratory of Electronics.

From 1947 to 1951, Charlie was a research physicist in the solid-state physics group at Bell Telephone Laboratories in Murray Hill, New Jersey, where he did research in theoretical solid-state physics with a focus on magnetism, ultra-sonics, and thermal properties of solids. His association with the Department of Physics at the University of California, Berkeley, began in 1950 with a visiting associate professorship. He joined the faculty as professor of physics the next year and became emeritus in 1978.

Charles Kittel is credited with building the solid-state (now condensed-matter) physics component of Berkeley’s physics department. In addition to his research contributions, he played a central role in hiring new faculty, and he worked closely with experimentalists who conducted groundbreaking research in semiconductors, magnetism, and nuclear magnetic resonance. He fostered and maintained an outstanding “theoretical school” composed of talented faculty along with exceptional postdoctoral researchers and graduate students. He and those associated with him had the reputation of being theorists who worked closely with experimentalists offering physical insights and suggestions for experiments in addition to mathematical approaches for solving physical problems. In addition to doing research and publishing at the cutting edge of condensed matter physics, Charlie established and developed undergraduate and graduate courses in condensed matter physics, in thermal physics, and in the introductory physics program. His texts in the above areas are classics. In particular, his Introduction to Solid State Physics, originally published in 1953 and now in its eighth edition, was not only the dominant text for teaching in the field, it was on the bookshelf of researchers in academia and industry throughout the world. In many ways, his choice of content defined solid-state physics for many years. He was an award-winning teacher. He received the Berkeley Division of the Academic Senate’s Distinguished Teaching Award in 1972 and the Oersted Medal from the American Association of Physics Teachers in 1979.

For much of his career, Charlie focused his research on topics related to understanding the properties of materials. These included semiconductors, magnetic behavior, ferroelectrics, optical properties, electron-spin and nuclear magnetic resonance, and superconductivity. In 1946 he showed that technologically important fine-particle ferromagnets had high coercivity because the particles remained single domain when fine enough. In 1946 James Griffiths found that the ferromagnetic resonance frequency in thin films is proportional to the square root of the product of magnetic induction B and the external field strength H instead of to H alone, as is the case in nuclear and paramagnetic resonance. Three months after Griffiths’ paper appeared, Charlie published his proof that the dependence arose from the demagnetizing field. That research and Charlie’s related early work substantially strengthened our theoretical understanding of ferro- and ferrimagnetism. He pointed out that glasses had low thermal conductivity because their structural disorder reduced the phonon mean free path on the atomic scale, an early recognition of the importance of strong disorder for transport.

Together with Malvin Ruderman, Kittel created a model for what today is known as the RKKY interaction (for Ruderman-Kittel-Kasuya-Yosida), now understood to explain giant magnetoresistance in layered materials. With Arthur Kip, Paul Levy, and Alan Portis, Charlie carried out one of the earliest studies of electron-spin resonance in color centers. Such centers are now of interest for quantum computing. 

In a classic paper on cyclotron resonance in p-type germanium, Charlie, Gene Dresselhaus, and Arthur Kip reported the first direct measurement of the kinematics of electrons in solids. They confirmed in quantitative detail the correctness of band theory and demonstrated the importance of including spin–orbit coupling. In many ways, this experiment and theoretical interpretation formed a basis for the quasiparticle concept associated with electronic properties. Charlie received the 1957 Oliver E. Buckley Prize of the American Physical Society for this work.

Charlie’s reputation as a leading theorist was international, and he lectured worldwide regarding his research accomplishments. His honors include being a Fellow of the American Physical Society, a Miller Professor at Berkeley, a Fellow of the American Academy of Arts and Sciences, and a member of the U.S. National Academy of Sciences.

He will be remembered by the colleagues whom he worked with and the students and postdoctoral researchers whom he mentored. Many members of his group became world leaders in the field of condensed matter physics. This list includes the late Nobel Laureate Pierre-Gilles de Gennes. Charlie is survived by his children, Peter, Ruth, and Timothy. He was predeceased by his wife Muriel.

Members of the physics community and readers of his texts will remember Charlie Kittel for his amazing ability to look at complex properties of matter and come up with simple models and accurate descriptions that defined the essence of the relevant physics involved. This ability was evident in his research publications and in his texts.

Marvin L. Cohen