http://dspace.nbuv.gov.ua:80/handle/123456789/122191 2026-04-11T18:48:30Z 2026-04-11T18:48:30Z Панкратова, М.Л. Ковалев, А.С. http://dspace.nbuv.gov.ua:80/handle/123456789/128090 2018-01-13T12:04:28Z 2015-01-01T00:00:00Z

Модель обменного смещения в трехслойной структуре ФМ/АФМ/ФМ Панкратова, М.Л.; Ковалев, А.С. Теоретически исследованы особенности явления обменного смещения в трехслойных структурах ФМ/АФМ/ФМ, которые активно исследуются экспериментально. В рамках предложенной дискретной модели ферромагнитных слоев таких многослойных структур получены зависимости намагниченности от внешнего магнитного поля. Показано, что на зависимостях намагниченности от поля наблюдаются горизонтальные плато, расщепление петли гистерезиса, ее асимметрия. Рассмотрено влияние дефектов интерфейса на явление обменного смещения и его особенности. Полученные результаты качественно со- гласуются с экспериментальными данными.; Теоретично досліджено особливості явища обмінного зсуву у тришарових структурах ФМ/АФМ/ФМ, які активно вивчаються експериментально. У рамках запропонованої дискретної моделі феромагнітних шарів таких багатошарових структур отримано залежності намагніченості від зовнішнього магнітного поля. Показано, що на залежностях намагніченості від поля спостерігаються горизонтальні плато, розщеплення петлі гістерезису, її асиметрія. Розглянуто вплив дефектів інтерфейсу на явище обмінного зсуву та його особливості. Отримані результати якісно узгоджуються з експериментальними даними.; The exchange bias phenomenon in the trilayer systems FM/AFM/FM which actively studied experimentally is theoretically investigated. In the proposed discrete model magnetization dependencies on external magnetic field are obtained. It is shown that on the magnetization dependencies on magnetic field the horizontal plateaus, splitting of the hysteresis loop, their asymmetries are observed. The impact of the interface defects on the exchange bias phenomenon and its features was studied. Obtained results are in qualitative agreement with experimental data.

2015-01-01T00:00:00Z Chung, S. Mohseni, S.M. Eklund, A. Dürrenfeld, P. Ranjbar, M. Sani, S.R. Nguyen, T.N.A. Dumas, R.K. Åkerman, J. http://dspace.nbuv.gov.ua:80/handle/123456789/128089 2018-01-06T01:03:10Z 2015-01-01T00:00:00Z

Magnetic droplet solitons in orthogonal spin valves Chung, S.; Mohseni, S.M.; Eklund, A.; Dürrenfeld, P.; Ranjbar, M.; Sani, S.R.; Nguyen, T.N.A.; Dumas, R.K.; Åkerman, J. We review the recent experimental advancements in the realization and understanding of magnetic droplet solitons generated by spin transfer torque in orthogonal nanocontact based spin torque nanooscillators (STNOs) fabricated on extended spin valves and spin valve nanowires. The magnetic droplets are detected and studied using the STNO microwave signal and its resistance, the latter both quasistatically and time-resolved. The droplet nucleation current is found to have a minimum at intermediate magnetic field strengths and the nature of the nucleation changes gradually from a single sharp step well above this field, mode-hopping around the minimum, and continuous at low fields. The mode-hopping and continuous transitions are ascribed to droplet drift instability and re-nucleation at different time scales, which is corroborated by time-resolved measurements. We argue that the use of tilted anisotropy fixed layers could reduce the nucleation current further, move the nucleation current minimum to lower fields, and potentially remove the need for an applied magnetic field altogether. Finally, evidence of an edge mode droplet in a nanowire is presented.

2015-01-01T00:00:00Z Bender, S.A. http://dspace.nbuv.gov.ua:80/handle/123456789/128088 2018-01-06T01:03:09Z 2015-01-01T00:00:00Z

Thermoelectric spin transport through ferromagnetic heterostructures Bender, S.A. We study how spin is transferred by ferromagnetic dynamics in a charge insulator in response to a thermoelectric bias, which is established by supplying heat and/or spin accumulation via normal leads. At zero temperature, magnetic anisotropies pin the macroscopic order, which necessitates a finite threshold bias to induce a spin current in a steady state of unpinned dynamics. At finite temperatures, however, thermal spin waves provide a spin transport channel in response to a linear thermoelectric bias. The theoretical description is rooted in the Landau–Lifshitz–Gilbert phenomenology both for the macroscopic dynamics of the magnetic order and quantum kinetics of thermal magnons. In this paper we connect the classical and quantum aspects of the underlying magnetic dynamics and spin transport, as well as provide a unified view of the exchange mediated bias of spin Seebeck physics of the magnetic interface and bulk.

2015-01-01T00:00:00Z Schroeter, S. Garst, M. http://dspace.nbuv.gov.ua:80/handle/123456789/128087 2018-01-06T01:03:08Z 2015-01-01T00:00:00Z

Scattering of high-energy magnons off a magnetic skyrmion Schroeter, S.; Garst, M. We discuss the scattering of high-energy magnons off a single magnetic skyrmion within the field-polarized ground state of a two-dimensional chiral magnet. For wavevectors larger than the inverse skyrmion radius,krs>>1 the magnon scattering is dominated by an emerging magnetic field whose flux density is essentially determined by the topological charge density of the skyrmion texture. This leads to skew and rainbow scattering characterized by an asymmetric and oscillating differential cross section. We demonstrate that the transversal momentum transfer to the skyrmion is universal due to the quantization of the total emerging flux while the longitudinal momentum transfer is negligible in the high-energy limit. This results in a magnon-driven skyrmion motion approximately antiparallel to the incoming magnon current and a universal relation between current and skyrmion-velocity.

2015-01-01T00:00:00Z