Leonid Vladimirovich Lutsev (L. V. Lutsev) passed away on 6 July 2020 due to complications associated with having contracted the coronavirus.
Born on 25 August 1955, Lutsev was a Russian physicist whose major focus of scientific interests and research was magnetic phenomena in thin films and bulk materials for device applications in the field of spintronics. His profound knowledge in the diverse disciplines of physics, along with a keenly developed sense of intuition, led Lutsev to conduct numerous experimental as well as theoretical studies (see, for example, these two studies) of the magnetic properties of these materials.
Beginning in 2012, Lutsev worked at the Ioffe Physical-Technical Institute in St. Petersburg, and he also collaborated with other research and industrial organizations.
One of his main research focuses was spin-wave excitation and spin-dependent electric transport phenomena in metal–dielectric heterostructures (linked paper in Russian). Among his discoveries is that in ferromagnetic thin films of nanoscale thickness with a film thickness less than a certain value, the process of merging spin-wave modes is forbidden, and low-damped spin waves can be observed. These waves facilitate the construction of spin-wave devices such as filters and delay lines operating in the microwave range with small losses.
He is also responsible for the discovery of the spin-excitation spectra of granular structures with ferromagnetic nanoparticles. He discovered that during spin-polarized excitations, change in the direction of the spin of a granular particle is accompanied by the transition of an electron between two sublevels of the particle in a split localized state and by change in polarization of this state. (Due to the mechanism of spin-polarized relaxation, granular structures have an anomalously high damping coefficient of spin excitations and a large FMR line-width.)
He further determined that the main factors influencing the dispersion of spin waves in granular structures are the conductivity and magnetic parameters of the structure. These factors change the shape of the dispersion curves in different ways, making it possible to determine their magnetic and electrical characteristics. The solution to the scientific problem of determining these characteristics from the dispersion dependences of spin waves led Lutsev to further develop and enhance existing methods of spin-wave spectroscopy, using these methods to study a-C:H(Cu), SiO2 with embedded nanoparticles of Co, ZnO(Co), BaTiO3 with embedded nanoparticles of Ni, a-C:H with embedded nanoparticles of Co, and structures of SiO2 with embedded nanoparticles of Co86Nb12Ta2.
For granular structures with metal nanoparticles below the percolation threshold, Lutsev determined, from the observed temperature dependences, the number of localized states through which tunneling passes between cluster electronic states (CES). (The processes of inelastic resonance tunneling through a chain of localized states in the amorphous layer between CES near the Fermi level with an energy spread of the order kT play an essential role in the mechanism of conduction.)
Lutsev developed multilayer thin broadband absorbing coatings of electromagnetic waves in the microwave range containing layers of a-C:H(Co, Ni) with absorption of at least 10 dB of incident electromagnetic radiation in the frequency range 8–80 GHz. (The developed radiation- absorbent coatings surpass the ferrite-based coatings by thickness, weight, and frequency absorption bandwidth.)
In the heterostructure SiO2(Co)/GaAs, where SiO2(Co) is a granular film of SiO2 embedded with nanoparticles of Co, the effect of giant magnetoresistance is observed. Lutsev determined that this giant magnetoresistance effect is associated with the formation of a spin-dependent barrier, the transparency and height of which are controlled by the magnetic field present. He demonstrated that the spin-dependent potential barrier is formed due to the exchange interaction between the electrons of the enriched layer in the semiconductor with d-electrons of Co, and that the large values of the magnetoresistance in heterostructures such as SiO2(Co)/GaAs during the avalanche process can be explained by the influence of the barrier on the development of the impact electron ionization.
Lutsev authored patents dealing with electromagnetic absorbing coating, the composition of absorbing electromagnetic radiation and methods for preparing this composition, the microwave element of an epitaxial structure, the radiation-absorbent coating, the radiation-absorbent coating and method for its production, and the radiation-absorbent material and method for producing radiation-absorbent coating (see list of patents below). He also authored monographs and text chapters (see below).
The author of this article is very much thankful to Lutsev for the valuable consultations and support during the time of her doctoral work at the Ioffe Institute. His numerous contributions to the development of the study of magnetic thin films and spintronics have been vast and significant, and he will be sorely missed, not by this author alone, but by untold numbers of other scientists who knew him and knew his work.
List of patents, monographs, and text chapters
- S. V. Yakovlev, L. V. Lutsev, G. A. Nikolaychuk, V. V. Petrov, A. V. Alferov, N. P. Milivskii, Patent for invention RU 2363714 C2, 19 September 2007.
- E. V. Gribanova, V. I. Ivanova, N. A. Lukyanova, L. V. Lutsev, A. A. Nikolaev, V. V. Shutkevich, S. V. Yakovlev, Patent for invention RU 2247759, 19 March 2004.
- E. V. Gribanova, V. I. Ivanova, N. A. Lukyanova, L. V. Lutsev, A. A. Nikolaev, V. V. Shutkevich, S. V. Yakovlev, Patent for invention RU 2247760, 19 March 2004.
- S. V. Yakovlev and L. V. Lutsev, Utility model patent RU 66612 U1, 29 November 2006.
- L. V. Lutsev, G. A. Nikolaychuk, V. V. Petrov, S. V. Yakovlev, Utility model patent RU84161 U1, 24 December 2008.
- A. G. Alekseev, A. P. Starostin, S. V. Yakovlev, L. V. Lutsev, S. V. Kozyrev, Patent for invention RU 2228565 C1, 19 December 2002.
- M. S. Andryushchenko, S. V. Kozyrev, V. P. Kudryavtsev, L. V. Lutsev, V. A. Slugin, I. M. Starobinets, E. A. Stager, Patent for invention RU 2502766 C1, 1 June 2012.
- L. Lutsev, Giant Injection Magnetoresistance. Experimental and Theoretical Studies, Application Prospects, Lambert Academic Publishing, Saarbrucken, Germany, 2013, 116 c., ISBN 978-3-659-43964-3.
- L. V. Lutsev, “Diagram technique for quantum models with internal Lie-group dynamics,” Mathematical Physics Research Developments; Editor Morris B. Levy, Nova Science Publishers, 2009, pp. 141-188, ISBN-13: 978-1-60456-963-6.
