Vladimir Idelevich Perel, a condensed-matter
theorist who was well known for his major contributions to the spin physics in semiconductors,
died of a heart attack on 11 October 2007 in Saint Petersburg, Russia.
Perel was born on 24 August
1928 in Sverdlovsk (now Ekaterinburg). After high school, just after the end of World War II, he
entered the physics department of the Leningrad State University, where he got his master's degree
in theoretical physics in 1950. Perel's talents were obvious to his teachers, including Vladimir
Fock, and to his fellow students, who jokingly referred to him as "professor."
Times were hard: The anti-Semitic
paranoia of Joseph Stalin was gaining momentum, and Perel had already lost his father, Idel, in
1938 during the Stalin terror purges. All first jobs after graduation were assigned by special
state commissions; Perel, the best student, was sent to teach physics in a small school in northern
Russia, where he worked for two years. After Stalin's death in 1953, the political climate improved,
and Perel was admitted to the University of Petrozavodsk. There he did his PhD thesis on plasma physics
with Yurii Kagan as his adviser. In 1958 he joined the theoretical group led by Lev Gurevich at the
Ioffe Institute in Leningrad (now Saint Petersburg).
Perel worked at the institute
for almost 50 years, up to his last days, and was one of its emblematic personalities. His early work
with Oleg Konstantinov was devoted to helicons in metals, coherence of atomic states in gases,
and light polarization in electroreflectance in semiconductors. The Konstantinov–Perel
diagram technique for nonequilibrium processes, developed in 1960 and widely used in the 1960s
and 1970s, is especially noteworthy; a somewhat similar but better-known technique was later
developed by Leonid Keldysh.
In the early 1960s, condensed-matter
theorists were generally excited about the application of Feynman diagrams and the mathematical
methods of quantum field theory to "normal" physics. It seemed that those methods provided foolproof
automatic machinery for obtaining correct solutions to any difficult problem. Perel, however,
came to the conclusion that no technique can help if one doesn't have a deep understanding of the
physics involved, but when such understanding is achieved, the path to results usually becomes
simple and transparent. Beginning in the 1970s, he never used his own, or any other, diagrammatic
technique.
Perel developed his own
style of theoretical work, based on physical intuition rather than on mathematical expressions;
that style greatly influenced the physics community of Saint Petersburg. Perel belonged to a rare
species of theorists who could establish a mutual understanding with experimentalists. He would
go into seemingly irrelevant details of an experiment and occasionally find that the origin of
some "discovery" was due to an unexpected parasitic effect. He also could focus on some minor feature
of the experimental data and initiate a promising direction of research.
In the 1970s and early 1980s,
Perel worked with one of us (Dyakonov) on optical and transport spin-related phenomena in semiconductors,
a subject then regarded as esoteric but recently gaining popularity under the name "spintronics."
Their best-known achievements were the discovery of an important mechanism of spin relaxation,
the explanation of the polarization properties of hot luminescence, and the theory of spectacular
optical effects due to nuclear spins. Their prediction of the spin Hall effect had to wait for more
than 30 years for the experimental confirmation that triggered the important theoretical and
experimental activity we witness today.
With Irina Yassievich
and Viktor Abakumov, Perel made a major contribution to the theory of recombination processes
in semiconductors. Their well-known book on that important but difficult subject, Nonradiative
Recombination in Semiconductors (North-Holland, 1991), became a sort of encyclopedia for
many researchers.
From 1991 until his death,
Perel was the editor-in-chief of the Russian journal Semiconductors and was the head of
the Ioffe Institute's group for semiconductor theory. He became a full member of the Russian Academy
of Sciences in 2000. Since 1973 he worked part-time at the Leningrad Electrotechnical Institute
teaching courses on solid-state physics that were exceptional for their clarity. Although those
responsibilities distracted him from what he liked most—his research—he took them
seriously, invariably creating an atmosphere of human decency, benevolence, and teamwork. Dozens
of physicists, including the four of us, consider Perel to be their true teacher in physics.
Many sought his advice
and suggestions in both scientific and difficult life matters, and they felt better after talking
with him. Perel presented an exceptional combination of talent, knowledge, modesty, tolerance,
and the highest moral standards. Highly esteemed and loved by everyone who knew him, he will be deeply
missed.
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