Gerald Dennis Mahan (November 24, 1937 – November 21, 2021) was an American condensed matter physicist, with specific research interests in transport and optical properties of materials, and solid-state devices. He is recognized for his work in quantum thermoelectricity and the invention of the zinc oxide varistor. He is also developed the time-dependent local-density approximation (TDLDA) and its author of various books in quantum many-body physics.
Upon graduation he became a research scientist at General Electric Research Laboratory (1963–1967). He worked full-time for General Electric (GE) until 1967 and then spent another 28 years working for them part-time, one of the longest part time continuous relationships in GE research history.[citation needed]
During his tenure at Indiana, he was invited by Stig Lundqvist of Chalmers University and the Niels Bohr Institute to spend a sabbatical year working at Chalmers in Göteborg, Sweden. This fostered a long collaboration with Chalmers and Swedish physics. In 1984 the University of Tennessee and Oak Ridge National Laboratory created a joint Distinguished Scientist program to raise the quality and profile of science in Tennessee. Mahan was recruited as the first member of that program and moved to Tennessee. He continued his research but spent much of his time as a research manager. During Lamar Alexander's tenure as President of the University of Tennessee, he recruited Mahan to teach freshman physics, which he did for ten years. At that time, there were not many members of the National Academy of Science teaching freshman physics. In 2001, Mahan was recruited to join the faculty of Pennsylvania State University as a distinguished professor. He expanded his areas of expertise to include thermoelectrics and thermal transport systems in nanotubes. He retired from Penn State in 2016 and served as an adjunct professor at the Massachusetts Institute of Technology from 2016 until 2020.
Later in his career, Mahan served as a leader of scientific organizations both in the United States and globally. He served as a general councilor (board of directors) of the American Physical Society. He served as secretary (head) of Section III of the National Academy of Science. Section III includes Applied Math, Computer Science, Engineering and Applied Physical Science. He also served as secretary of Section 33 (Applied Physical Science). He served as the first chairman of the International Centre for Condensed Matter Physics (ICCMP) in Brasilia, Brazil. In his role as chairman of ICCMP he traveled relentlessly to foster collaboration between South American and US and European physicists.
Work
While at GE, Mahan pioneered the application of mathematical techniques developed by three Russians: Alexei Abrikosov, Lev Gor'kov and Igor Dzyaloshinskii; to adapt Green's functions to theoretical solid-state physics. The x-ray edge theory was part of this work. The results produced using this method, while controversial at the time, were almost universally supported by later experimental results and eventually became accepted as fundamental mathematical techniques. Charles Duke worked closely with Mahan while they were both at GE and learned and applied these techniques leading to discoveries in the tunneling of electrons across semiconductor diodes. He is quoted in an interview as saying that "basically, Gerry taught me solid-state physics".[1][2]
During his tenure at Indiana, he expanded his areas of work to include varistors, which he did in conjunction with colleagues from GE. He developed mathematical models that explained how varistors function (they are extremely non-linear devices) leading to substantial improvements in their effectiveness. He worked closely with Lloyd Chase and did the first Raman scattering of beta-alumina which is used to make high-density solid-state batteries.
Mahan was committed to the development of scientific talent and had several post doctorate students while at Indiana. These included Steven Girvin (postdoc for 2 years from 1977 to 1978), Wilfried Haensch (postdoc for 2 years from 1981 to 1982),[3] William Pardee, Ji-Wie Wu, Mats Jonson and Petter Minnhagen. Wilfried Haensch did pioneering work with Mahan explaining the current drag problem in semi-conductors and separate work with Mahan using new analytical methods to explain the quantum Bolzmann equation which describes the transport of electricity in heat and solids.
In Penn State University, he worked with Peter Eklund on vibrational properties of carbon nanotubes and silicon nanowires.
M. W. Cole, V. H. Crespi, M. S. Dresselhaus, G. Dresselhaus, J. E. Fischer, H. Rodriguez Gutierrez, K. Kojima, G. D. Mahan, A. M. Rao, J. O. Sofo, M. Tachibana, K. Wako, Q. Xiong (2010). "Structural, electronic, optical and vibrational properties of nanoscale carbons and nanowires: a colloquial review". J. Phys. Condens. Matter. 22 (33): 334201. Bibcode:2010JPCM...22G4201C. doi:10.1088/0953-8984/22/33/334201. PMID21386491. S2CID2513464.{{cite journal}}: CS1 maint: multiple names: authors list (link).
M. W. Cole, V. H. Crespi, G. Dresselhaus, M. S. Dresselhaus, G. Mahan, and J. O. Sofo (2010). "Peter Clay Eklund: a scientific biography". J. Phys. Condens. Matter. 22 (33): 330301. doi:10.1088/0953-8984/22/33/330301. PMID21386361.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^Chang, Leland, Robert K. Montoye, Yutaka Nakamura, Kevin A. Batson, Richard J. Eickemeyer, Robert H. Dennard, Wilfried Haensch, and Damir Jamsek (2008). "An 8T-SRAM for variability tolerance and low-voltage operation in high-performance caches". IEEE Journal of Solid-State Circuits. 43 (4): 956–963. Bibcode:2008IJSSC..43..956C. doi:10.1109/JSSC.2007.917509. S2CID813235.{{cite journal}}: CS1 maint: multiple names: authors list (link) (See author information.)