Leo K. Kovalev, 1941 - 2014, Remembered

February 7, 2014 (PO26). On January 28, 2014, Prof. Leo K. Kovalev suddenly passed away in Moscow from a myocardial infarction at the age of 72. To the superconducting electro-machinery community, Leo K. Kovalev was well known worldwide through his work on electric machines with HTS bulk elements, comprising hysteresis motors, reluctance motors and motors utilizing permanent magnets. He also paid great attention to HTS-magnetic-suspension systems for high-speed rail-borne transportation and flywheels.

In 1964, he started his professional career at the Central Institute of Aircraft Engines, Moscow, after graduating from Moscow State Technical University Named After N. E. Bauman. A few years later he joined the Department of Electric Machines, the Dept. 310, of the Moscow Aviation Institute (MAI), headed by Prof. Albert I. Bertinov. During that time he pursued research in the field of MHD (magneto-hydrodynamic) energy conversion, and in 1972 he finished his Science Candidate (doctoral) dissertation on MHD generators. For the following ten years his research activity shifted to ionosphere radio physics, hydrodynamics and radio waves propagation at the Scientific Research Institute of Long-Haul Radio. During 1980-1982 he was the Deputy General Constructor of that institute. In 1982 he returned to the Dept.310 of MAI, headed at that time by Prof. Dmitry A. But, and continued research on MHD problems and in parallel extended his interest to low-temperature superconducting electric machines. When In 1986, when high-temperature superconductivity (HTS) was discovered, Leo concentrated his research on HTS electric machines and developed several series of cryogenic electric machines utilizing bulk HTS elements, operating at liquid nitrogen temperatures. He is the author of four books and more than 200 scientific and technical papers. In 1996 he attained his D.Sc. (habilitation equivalent) degree and became a Professor. Since 2002 he headed Dept. 310 of MAI, and in that same year he was awarded the State Prize of Russian Government in the field of Science and Technology. He initiated “The Centre of Superconducting Electric Machines and Devices” at MAI. Leo was an enthusiastic specialist in electromechanics, applied superconductivity, hydrodynamics and radio physics. He liked to first identify new scientific problems and then to solve them.

He actively took part in the international development of superconducting electric machines and was one of the initiators of the German-Russian cooperation, leading to the design and development of superconducting electric motors with liquid nitrogen cooling. The consortium comprised: Oswald Elektromotoren GmbH (Miltenberg), Stuttgart Technical University, IPHT (Jena), IFW (Dresden), Moscow Aviation Institute, A.A. Bochvar All-Russian Scientific Research Institute for Inorganic Materials (Moscow), All-Russian Electrotechnical Institute (Moscow), and the Institute for Solid State Physics (Chernogolovka, Moscow region).

Prof. Leo K. Kovalev was an Academician of the Russian Academy of Electrotechnical Sciences, an Honored Scientist of Russian Federation (RF), and an advisory council member of Highest Certifying Commission (RF).

Besides his research activities, Leo K. Kovalev was a true intellectual and a real friend for all his partners. Everyone who visited his Moscow home or countryside residence was surrounded with hospitality and warmth. He possessed a rare gift of charming his interlocutor from the very first words of communication.  He left behind his dear wife Tatiana and a son, who like all of us will miss him very much.

Vladimir T. Penkin and Konstantin L. Kovalev

Nikolai Kopnin, Low-temperature Physicist

January 2, 2014 (PO25). Our friend and colleague Professor Nikolai Borisovich Kopnin passed away on October 20, 2013, during a lecturing trip to Rome. He was 67 years old.

Nikolai Kopnin had been a frequent visitor at the Aalto Low Temperature Laboratory1 for several years until in 2000 he became a member of the staff.  His early collaboration with the Laboratory was on the dynamics of quantized vortices in helium-3 superfluids.  Lately, his studies contributed extensively to the development of superconducting nanoelectronics, the new backbone of the Laboratory's research.

Nikolai received his physics education in Moscow. In 1973 he defended his PhD thesis on vortices in Type II superconductors under the supervision of Academician Lev P. Gor’kov in the Landau Institute of Theoretical Physics. He remained a researcher of the Landau Institute, and in 1984 he received his higher doctoral degree.  In 2011, he was awarded the International Francis Simon Prize (together with his Landau colleague, S.V. Iordanskii).  The Prize was for his work on forces acting on quantum vortices in superfluids and superconductors. One of these forces is now known as the "Kopnin force".

The main area of Nikolai Kopnin's research was superconductivity, primarily its non-equilibrium and non-stationary phenomena. His research work has been highly recognized and he was one of the leading experts in this field worldwide, as shown by the citations of his monograph “Nonequilibrium superconductivity" (Oxford University Press, 2001).  He has contributed to the studies of anisotropic and layered superconductors, developed the microscopic theories for dissipative and non-stationary flow in Fermi superfluids, in particular in superfluid 3He, worked on new mechanisms for the formation of topological defects during rapid quench-cooled phase transitions, which has applications in cosmology, and he constructed theories of superfluid quantum turbulence.  During more recent years he investigated the physics of mesoscopic structures and devices, including graphene.  He published more than 150 highly cited articles in leading international journals.

Already in 1991, by extending his theory of the "Kopnin force" to chiral superfluids Nikolai predicted the existence of fermionic bound states, which have exactly zero energy. Today these quasiparticles are known as Majorana fermions - objects, which are still elusive in particle physics but may be observable in topological superfluids and superconductors.  The bound states in chiral superfluids found by him have in addition the remarkable property that their spectrum is dispersionless.  Now such flat bands are intensively searched for in solid-state materials.  According to Nikolai’s recent work, the singular density of states in materials with a flat band may open the route to superconductivity at room temperature.

Nikolai Kopnin was a modest person who was always fair and considerate to his colleagues and friends, and they considered him a noble man with a strong passion for science.  He was a person whom one could always trust and who dedicated and committed himself fully to his research activity.  His free time Nikolai devoted to his family and enjoyed interesting hikes and journeys to wilderness. Those who were fortunate to be friends with Nikolai know that there is nothing better to look for. 

Nikolai was always caring and loyal, with warm human spirits and intelligent sense of humor.

Matti Krusius, Jukka Pekola and Grigori Volovik

1Aalto University, School of Science, FI-00076 Aalto, Finland.

Vladimir Pan Remembered

November 6, 2013 (PO23).  On 20 September 2013, Prof. Vladimir M. Pan passed away at 82. Vladimir was an Emeritus Professor at the Institute of Metal Physics (IMP) of the National Academy of Sciences of Ukraine and at the Taras Shevchenko National University of Kiev. Over four decades he successfully led the Department of Superconductivity, which he founded in 1970 at the Institute of Metal Physics in Kiev (USSR, now Ukraine).

Born on 15 September 1931 in Kharkov, USSR, Vladimir earned his first degree (Master of Science) at the Kiev Polytechnic Institute in 1955. In the same year, he joined the Institute of Metal Physics, where he defended his PhD in 1961, working on phase diagrams of metals. This experience had allowed him later to merge the fields of Materials Science and Superconductivity and to establish a new research direction in Ukraine, the Science of Superconducting Materials.

John Clem Passed Away

August 7, 2013 (PO21).  Professor John R. Clem passed away on August 2, 2013, after a four year battle with mesothelioma. 

John was born in 1938 in Waukegan, Illinois; his parents were trained as teachers.  John received scholarships at the University of Illinois, where he obtained his undergraduate degree in engineering physics. John then earned his Ph.D. in superconductivity under John Bardeen.  After postdoctoral appointments in Maryland and München/Germany, John joined the Iowa State University Physics Department and Ames Laboratory in 1967 and enjoyed 46 years of collaboration with ISU and Ames Lab colleagues.  For the community of people dealing with a broad field of type-II superconductivity, John's name is and will always be associated with such hits as "pancake vortices", the term coined by John soon after the discovery of layered high-Tc cuprate superconductors.  John established and edited the tremendously successful and useful “High-Tc Update” from 1987 to 2000, well remembered by all participants in the high-Tc boom.  Among many other contributions to superconducting phenomenology, John’s papers on ac losses, edge pinning, flux-cutting, and recently on critical currents in superconducting thin-film strips of various shapes – a hot topic in superconducting electronics – will be remembered and cited in years to come.

John was also an avid vocalist, who enjoyed singing baritone on many occasions, conference banquets included. John is survived by his wife Judy Clem, his sister Caryl Clem, children Paul Clem and Jean (Clem) Latzke, and three grandchildren.  

By Vladimir Kogan, Ruslan Prozorov, and Doug Finnemore, Iowa State University, and Ames Lab

Two Editors of SNF mourn John as a good friend and source of inspiration. One of us (AIB) benefitted greatly from his advice and less-known theoretical work not mentioned in the obituary.

Alex I. Braginski and Herbert C. Freyhardt