A family of physicians
Alexei Alexeyevich Abrikosov was born in Moscow on June 25, 1928. Both his parents were physicians. His father was Alexei Ivanovich Abrikosov; his mother, Fanny Davidovna Wulf, was Jewish. Through his father he was a nephew of Anna Abrikosova, a Catholic nun persecuted under Soviet rule.
He finished high school in 1943, in the middle of the war, and began studying at the Moscow Institute for Power Engineers. In 1945 he transferred to physics at Moscow State University, graduating in 1948.
Landau’s student
He went on to graduate work at the Institute for Physical Problems in Moscow, now the Kapitza Institute, under Lev Landau, the great theorist whose school dominated Soviet physics. He received his candidate degree, the Soviet equivalent of a PhD, in 1951 for a thesis on thermal diffusion in plasmas, and his higher doctorate in 1955 for work on quantum electrodynamics at high energies.
In 1950 Landau and Vitaly Ginzburg had published a theory of superconductivity, the ability of some metals to carry electricity with no resistance at all when cooled close to absolute zero. Abrikosov set out, with the experimentalist Nikolai Zavaritskii, to test one of its predictions on thin metal films. The results led him to a new class of materials, which he called superconductors of the second group, now known as type-II superconductors.
Electricity without resistance
Superconductivity had been a mystery since its discovery in 1911. A wire made of a superconductor, cooled to a few degrees above absolute zero, carries current with no electrical resistance at all, so no energy is lost as heat; a current set flowing in a superconducting loop can circulate for years. Superconductors also push magnetic fields out of their interior. The first microscopic explanation, the theory of John Bardeen, Leon Cooper and Robert Schrieffer, came only in 1957 and was rewarded with the Nobel Prize in 1972. It explained the simpler, type-I superconductors well, but the Nobel committee later noted that it proved inadequate for the technically most important materials.
Ginzburg and Landau had taken a different route in 1950, describing the superconducting electrons by a single collective wave, an order parameter, whose behaviour could be calculated without knowing the microscopic details. The theory introduced a number that measured how a superconductor responded to a magnetic field. Abrikosov worked out what happens when that number is large.
Whirlpools in a superconductor
Ordinary, type-I superconductors push magnetic fields out completely. But that makes them fragile: a moderate magnetic field destroys their superconductivity. Some alloys behaved differently, letting magnetic field in gradually while staying superconducting, and experimenters in the 1930s had seen this but blamed impurities in their samples.
Using the Ginzburg-Landau equations, Abrikosov showed in a paper published in 1957 what was really happening. In these materials, magnetic field enters through thin threads, each carrying a single quantum of magnetic flux and surrounded by a swirling current, like tiny whirlpools in the flow of superconducting electrons. The rest of the material stays superconducting. As the field grows, the vortices pack more tightly into a regular array, now called the Abrikosov vortex lattice, until their cores overlap and superconductivity is lost. His theory fitted the old measurements perfectly. Experimenters accepted it only about ten years later, when the vortex lattice was made visible by sprinkling magnetic particles on the surface of a superconductor.
Abrikosov predicted in detail how the number of vortices grows as the field increases and how superconductivity finally disappears when their cores overlap. Because type-II materials can stay superconducting with the field threaded through them, they remain superconducting in much stronger magnetic fields than type-I superconductors, which is what makes them useful. The Nobel committee observed that his papers from the late 1950s were being cited more and more often in the decade before the prize, as new superconducting materials were developed and analysed with his theory.
The magnets of modern medicine
Type-II superconductors are the technically important kind, because they keep carrying current without resistance even in very strong magnetic fields. That property is what makes powerful superconducting magnets possible, and Abrikosov’s theory explains how and why they work. It is still used to develop and analyse new superconducting materials and magnets.
The most familiar use is in medicine. Magnetic resonance imaging scanners use strong superconducting magnets to make detailed pictures of the brain, heart, joints and other soft tissue without X-rays; as the Nobel committee noted, all of these strong magnets are type-II superconductors. Most MRI systems use wire made of niobium-titanium, a type-II superconductor, and MRI accounts for the great majority of the world superconductor market.
The same materials make big science possible. The magnets that steer protons around the 27-kilometre ring of CERN’s Large Hadron Collider contain about 1,200 tonnes of niobium-titanium cable.
A wide-ranging theorist
Abrikosov’s curiosity ranged far beyond superconductivity. In the 1950s he studied how hydrogen turns metallic under enormous pressure and what that means for the interiors of giant planets. With Lev Gor’kov he extended the microscopic theory of superconductivity and discovered that magnetic impurities can produce gapless superconductivity. He explained an effect in metals with magnetic impurities now called the Abrikosov-Suhl resonance, developed theories of semimetals such as bismuth, of gapless semiconductors and of one-dimensional metals.
With Gor’kov and Igor Dzyaloshinskii he wrote Methods of Quantum Field Theory in Statistical Physics, published in Russian in 1961 and translated into English, German, Chinese and Japanese. For decades it has been a standard textbook for physicists learning the theory of solids and liquids. He also wrote textbooks on the theory of metals and taught for four decades at Moscow universities.
Abrikosov taught almost all his working life. He was assistant, associate and then full professor at Moscow State University from 1950 to 1969, taught at Gorky University, now Nizhny Novgorod, from 1970 to 1972, and held the chair of theoretical physics at the Moscow Institute of Steel and Alloys from 1976 to 1991. In the United States he became an adjunct professor at the University of Illinois at Chicago and the University of Utah, and he held a visiting chair at Loughborough University in Britain.
He also wrote for students. His Introduction to the Theory of Normal Metals appeared in 1971, and Fundamentals of the Theory of Metals, which took him three years, in 1988; both were translated into English. In 1989 he, Gor’kov and Dzyaloshinskii received the Landau Prize of the Soviet Academy of Sciences for their textbook on quantum field theory methods.
The fortunes of Landau’s school changed in 1962, when Landau was gravely injured in a car accident. He survived but never returned to science, and he died in 1968. Afterwards, Abrikosov recalled, the attitude to theorists at the Institute for Physical Problems changed, and Landau’s group began to think about leaving, which led to the founding of the Landau Institute.
From Moscow to Argonne
In 1965 he helped found the Landau Institute for Theoretical Physics, where he headed condensed matter theory, and in 1988 he became director of the Institute for High Pressure Physics near Moscow. He received the Lenin Prize in 1966, shared with Ginzburg and Gor’kov.
In 1991, as the Soviet Union came apart, he accepted an offer from Argonne National Laboratory near Chicago and became a Distinguished Argonne Scientist. There he worked on the high-temperature superconductors discovered in the 1980s and on magnetoresistance, the change in a material’s electrical resistance in a magnetic field, introducing the idea of quantum linear magnetoresistance in 1998. He became a U.S. citizen in 1999 and was elected to the U.S. National Academy of Sciences in 2000 and as a Foreign Member of the Royal Society in 2001.
At Argonne he developed a theory of the high-temperature copper-oxide superconductors based on the special features of their electron energies, which he used to explain many of their unusual properties. In analysing experiments at Argonne and the University of Chicago, he recognised that quantum linear magnetoresistance had in fact first been seen by Pyotr Kapitza as early as 1928, but had been mistaken for a different effect.
Heritage
Abrikosov’s Jewish heritage came through his mother, Fanny Wulf; his father’s family was Russian. Like many Soviet scientists of his generation, he did not write publicly about religion or about Jewish identity, and his autobiography concerns his science. He belonged to the remarkable school of Lev Landau, himself of Jewish origin, which trained many of the leading theoretical physicists of the Soviet Union.
Last years and legacy
In 2003 Abrikosov shared the Nobel Prize in Physics with Vitaly Ginzburg and Anthony Leggett for pioneering contributions to the theory of superconductors and superfluids. He was married and had two sons and a daughter. He retired from Argonne and died in Palo Alto, California, on March 29, 2017, aged 88.
Abrikosov received many other honours, including the Fritz London Memorial Prize in 1972 for his work in low-temperature physics, the USSR State Prize in 1982 for work on semimetals and gapless semiconductors, and in 1991 the John Bardeen Award, shared with Ginzburg and Gor’kov.
His vortices are now a basic idea in physics, appearing in superconductors, superfluids and even theories of the early universe. And every time a patient slides into an MRI scanner, the magnet around them works in the way Abrikosov first explained in 1957.
Sources & further reading
Alexei A. Abrikosov, Biographical, NobelPrize.org · Press release: The Nobel Prize in Physics 2003, NobelPrize.org · Popular information: The Nobel Prize in Physics 2003, NobelPrize.org · Niobium–titanium, Wikipedia · Alexei Abrikosov (physicist), Wikipedia · Researched from the sources above and checked against them. Spotted an error? Tell us.
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