in a room-temperature magnon Bose-Einstein condensate Oleksandr - PowerPoint PPT Presentation

Spin transport by a supercurrent in a room-temperature magnon Bose-Einstein condensate Oleksandr Serha (Alexander A. Serga) Fachbereich Physik and Landesforschungszentrum OPTIMAS Technische Universität Kaiserslautern Germany Oleksandr Serha Seminar at the Center for Theoretical Physics of New York City College of Technology May 18, 2017

Kaiserslautern University City in the State of Rhineland-Palatinate (Rheinland-Pfalz) Hamburg Hamburg Amsterdam Berlin London Berlin Kaiserslautern Frankfurt Brussels Frankfurt Stuttgart Paris Munich Kaiserslautern Stuttgart Munich Oleksandr Serha Seminar at the Center for Theoretical Physics of New York City College of Technology May 18, 2017

Kaiserslautern University Oleksandr Serha Seminar at the Center for Theoretical Physics of New York City College of Technology May 18, 2017

AG Magnetismus Jun. Prof. Dr. E. Th. Papaioannou, Dr. P. Pirro, V. Lauer, Dr. B. Leven, T. Fischer, T. Langner, Dr. D. Passarello, M. Kewenig, P. Jaeger, L. Mihalceanu, T. Noack, H. Schäfer, B. Heinz, D. A. Bozhko, Dr. P. Clausen, M. Schneider, M. Geilen, Dr. habil. A. A. Serga, S. Keller, M. Schweizer, Dr. V. I. Vasyuchka, Prof. Dr. B. Hillebrands, T. Meyer, Dr. A. Conca Parra, F. Heussner Oleksandr Serha Seminar at the Center for Theoretical Physics of New York City College of Technology May 18, 2017

Concept of magnon spintronics Magnon transport plays a central role in magnonics A.V. Chumak, V.I. Vasyuchka, A.A. Serga, B. Hillebrands, Magnon spintronics , Nat. Phys. 11 , 453 (2015) Oleksandr Serha Seminar at the Center for Theoretical Physics of New York City College of Technology May 18, 2017

Computing principles Computing principles PERFORMANCE Oleksandr Serha Seminar at the Center for Theoretical Physics of New York City College of Technology May 18, 2017

Computing principles Computing principles PERFORMANCE Macroscopic quantum states and magnon supercurrents Oleksandr Serha Seminar at the Center for Theoretical Physics of New York City College of Technology May 18, 2017

Collaborators Magnon-supercurrent-team University of Kaiserslautern (Germany) Timo Alexander Halyna Laura Pascal Noack Kreil Musiienko-Shmarova Mihalceanu Frey Dmytro Vitaliy Oleksandr Burkard Bozhko Vasyuchka Serha Hillebrands Oleksandr Serha Seminar at the Center for Theoretical Physics of New York City College of Technology May 18, 2017

Collaborators External collaborators Taras Shevchenko National University of Kyiv (Ukraine) Weizmann Institute of Science (Israel) Gennadii Melkov Oakland University (USA) Victor L ' vov Anna Pomyalov Andrey Slavin Vasyl Tiberkevich Oleksandr Serha Seminar at the Center for Theoretical Physics of New York City College of Technology May 18, 2017

Experimental and theoretical inspiration of supercurrents studies Oleksandr Serha Seminar at the Center for Theoretical Physics of New York City College of Technology May 18, 2017

Magnons  q Oleksandr Serha Seminar at the Center for Theoretical Physics of New York City College of Technology May 18, 2017

Magnon gas Magnon as a quanta of spin-wave  Energy  Momentum  Mass s  1  Spin  Four- and three-magnon scattering Oleksandr Serha Seminar at the Center for Theoretical Physics of New York City College of Technology May 18, 2017

Magnon gas  Linear process Two-magnon scattering e 1 , p 2 e 1 , p 1  Nonlinear processes Three-magnon decay Three-magnon confluence e 1 , p 1 e 2 , p 2 e 3 , p 3 e 1 , p 1 e 2 , p 2 e 3 , p 3 Four-magnon scattering e 1 , p 1 e 3 , p 3 e 2 , p 2 e 4 , p 4 Oleksandr Serha Seminar at the Center for Theoretical Physics of New York City College of Technology May 18, 2017

Magnon gas  Linear process Two-magnon scattering e 1 , p 2 e 1 , p 1  Nonlinear processes Three-magnon decay Three-magnon confluence Gas of interacting magnetic quasiparticles e 1 , p 1 e 2 , p 2 e 3 , p 3 e 1 , p 1 Number of quasiparticles is conserved e 2 , p 2 e 3 , p 3 Four-magnon scattering e 1 , p 1 e 3 , p 3 e 2 , p 2 e 4 , p 4 Oleksandr Serha Seminar at the Center for Theoretical Physics of New York City College of Technology May 18, 2017

Yttrium Iron Garnet Y 3 Fe 5 O 12 (YIG) “Yttrium -Iron Garnet is a marvel of nature. Its role in the physics of magnets is analogous to that of germanium in semiconductor physics, water in hydrodynamics, and quartz in crystal acoustics .” V. Cherepanov, I. Kolokolov, and V. L’vov , The saga of YIG: spectra, thermodynamics, interaction and relaxation of magnons in a complex magnet , Phys. Rep. 229 , 81 – 144 (1993). Oleksandr Serha Seminar at the Center for Theoretical Physics of New York City College of Technology May 18, 2017

Yttrium Iron Garnet Y 3 Fe 5 O 12 (YIG) “Yttrium -Iron Garnet is a marvel of nature. Its role in the physics of magnets is analogous to that of germanium in semiconductor physics, water in hydrodynamics, and quartz in crystal acoustics .” V. Cherepanov, I. Kolokolov, and V. L’vov , The saga of YIG: spectra, thermodynamics, interaction and relaxation of magnons in a complex magnet , Phys. Rep. 229 , 81 – 144 (1993). YIG (the Father of Serpents) appears as a serpent man, serpent with bat-like wings, or as a giant snake. H.P. Lovecraft and Z. Bishop “The Curse of Yig ” (1929) Oleksandr Serha Seminar at the Center for Theoretical Physics of New York City College of Technology May 18, 2017

Yttrium Iron Garnet Y 3 Fe 5 O 12 (YIG) “Yttrium -Iron Garnet is a marvel of nature. Its role in the physics of magnets is analogous to that of germanium in semiconductor physics, water in hydrodynamics, and quartz in crystal acoustics .” V. Cherepanov, I. Kolokolov, and V. L’vov , The saga of YIG: spectra, thermodynamics, interaction and relaxation of magnons 1 1 0 1 1 0 in a complex magnet , Phys. Rep. 229 , 81 – 144 (1993). 4 2 4 2 1 1 1 4 2 2 Unit cell 48 oxygen atoms Magnetic moment of a unit cell is 8 octahedral iron atoms (spin 5/2 up) 10 Bohr magnetons 12 tetrahedral iron atoms (spin 5/2 down) at zero temperature 12 dodecahedral yttrium atoms Bulk YIG crystal 1 1 0 4 2 y x z Wiki Oleksandr Serha Seminar at the Center for Theoretical Physics of New York City College of Technology May 18, 2017

Yttrium Iron Garnet Y 3 Fe 5 O 12 (YIG) “Yttrium -Iron Garnet is a marvel of nature. Its role in the physics of magnets is analogous to that of germanium in semiconductor physics, water in hydrodynamics, and quartz in crystal acoustics .” V. Cherepanov, I. Kolokolov, and V. L’vov , The saga of YIG: spectra, thermodynamics, interaction and relaxation of magnons 1 1 0 1 1 0 in a complex magnet , Phys. Rep. 229 , 81 – 144 (1993). 4 2 4 2 1 1 1 4 2 2 Unit cell 48 oxygen atoms Magnetic moment of a unit cell is 8 octahedral iron atoms (spin 5/2 up) 10 Bohr magnetons 12 tetrahedral iron atoms (spin 5/2 down) at zero temperature 12 dodecahedral yttrium atoms Bulk YIG crystal  Longest known magnon lifetime (up to 700 ns ) 1 1 0 4 2  High Curie temperature y T ≈ 560 K x  Very low acoustic damping z Wiki Oleksandr Serha Seminar at the Center for Theoretical Physics of New York City College of Technology May 18, 2017

Yttrium Iron Garnet Y 3 Fe 5 O 12 (YIG) “Yttrium -Iron Garnet is a marvel of nature. Its role in the physics of magnets is analogous to that of germanium in semiconductor physics, water in hydrodynamics, and quartz in crystal acoustics .” V. Cherepanov, I. Kolokolov, and V. L’vov , The saga of YIG: spectra, thermodynamics, interaction and relaxation of magnons 1 1 0 1 1 0 in a complex magnet , Phys. Rep. 229 , 81 – 144 (1993). 4 2 4 2 1 1 1 4 2 2 Unit cell 48 oxygen atoms Magnetic moment of a unit cell is 8 octahedral iron atoms (spin 5/2 up) 10 Bohr magnetons 12 tetrahedral iron atoms (spin 5/2 down) at zero temperature 12 dodecahedral yttrium atoms Single-crystal YIG film  Longest known magnon lifetime (up to 700 ns ) 1 1 0 4 2  High Curie temperature y T ≈ 560 K x  Very low acoustic damping z Scientific Research Company “Carat”, Lviv, Ukraine Oleksandr Serha Seminar at the Center for Theoretical Physics of New York City College of Technology May 18, 2017

Magnon spectrum of in-plane magnetized YIG film Landau-Lifshitz equation: dipolar interaction exchange interaction  2 q Thickness modes having a non-uniform harmonic distribution of  2 q dynamic magnetization along the film thickness 6 µm thick YIG film Oleksandr Serha Seminar at the Center for Theoretical Physics of New York City College of Technology May 18, 2017

Magnon distribution Magnons are bosons ( s =1) and similar to other quasi-particles are described in thermal equilibrium by Bose-Einstein distribution with zero chemical potential µ=0 Bose-Einstein distribution µ: chemical potential Oleksandr Serha Seminar at the Center for Theoretical Physics of New York City College of Technology May 18, 2017

Control of magnon gas density by parametric pumping f p Parametric pumping Energy and by electromagnetic wave momentum at microwave frequency conservation laws µ=0 f p /2 Bose-Einstein distribution µ: chemical potential Oleksandr Serha Seminar at the Center for Theoretical Physics of New York City College of Technology May 18, 2017