Sökning: "spin waves"

Visar resultat 1 - 5 av 30 avhandlingar innehållade orden spin waves.

1. 1. Magnetization Dynamics in Nano-Contact Spin Torque Oscillators : Solitonic bullets and propagating spin waves

   Författare :Stefano Bonetti; Johan Åkerman; Thomas Silva; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; magnetism; spintronics; thin magnetic films; spin transfer torque; magnetization dynamics; spin waves; microwave oscillators; giant magneto-resistance; Magnetism; Magnetism;

   Sammanfattning : Magnetization dynamics in nano-contact spin torque oscillators (STOs) is investigated from an experimental and theoretical point of view. The fundamentals of magnetization dynamics due to spin transfer torque are given. A custom-made high frequency (up to 46 GHz) in large magnetic fields (up to 2. LÄS MER

3. 2. Magnetodynamics of pseudo spin valves investigated using co-planar waveguide and spin torque ferromagnetic resonance techniques

   Författare :Masoumeh Fazlali; Göteborgs universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Spintronics; Nanocontact pseudo spin valve; Spin waves; Oersted field; Interlayer exchange coupling; Acoustic and optical modes; Spin pumping; Spin transfer torque; Slonczewski mode; Collective mode;

   Sammanfattning : Nanocontact spin-torque nano-oscillators (NC-STNOs), based on magnetic multilayers, can generate a wide range of highly nonlinear localized and propagating spin wave modes for use in magnonics. In this thesis, we study some aspects of these structures from the fundamental physics point of view using the spin torque ferromagnetic resonance technique (ST-FMR) and conventional broadband FMR technique. LÄS MER

4. 3. Determining and Optimizing the Current and Magnetic Field Dependence of Spin-Torque and Spin Hall Nano-Oscillators : Toward Next-Generation Nanoelectronic Devices and Systems

   Författare :Seyed Amir Hossein Banuazizi; Johan Åkerman; Erik Wahlström; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; nanoelectronics; spintronics; nanomagnetism; ferromagnetic materials; microwave oscillators; magnetization dynamics; spin waves; giant magneto-resistance; spin Hall effect; spin-torque nano-oscillators; spin Hall nano-oscillators; numerical modeling; electrical characterization; microwave characterization; magnetic force microscopy.; Fysik; Physics; Teknisk materialvetenskap; Materials Science and Engineering; Informations- och kommunikationsteknik; Information and Communication Technology; Electrical Engineering; Elektro- och systemteknik;

   Sammanfattning : Spin-torque and spin Hall nano-oscillators are nanoscale devices (about 100 nm) capable of producing tunable broadband high-frequency microwave signals ranging from 0.1 GHz to over 65 GHz that several research groups trying to reach up to 200 - 300 GHz. LÄS MER

5. 4. Spin Dynamics and Magnetic Multilayers

   Författare :Björn Skubic; Olle Eriksson; Lars Nordström; Mark D. Stiles; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physics; magnetism; electronic structure; density functional theory; spin dynamics; spin-transfer torque; spin-density wave; multilayer; interface structure; Fysik;

   Sammanfattning : Theoretical studies based on first-principles theory are presented for a number of different magnetic systems. The first part of the thesis concerns spin dynamics and the second part concerns properties of magnetic multilayers. The theoretical treatment is based on electronic structure calculations performed by means of density functional theory. LÄS MER

7. 5. Theoretical Studies of Two-Dimensional Magnetism and Chemical Bonding

   Författare :Oleksiy Grechnyev; Olle Eriksson; Alexander Lichtenstein; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physics; spin Hamiltonians; quantized spin models; Heisenberg model; spin waves; self-consistent spin-wave theory; dipolar interaction; density functional theory; chemical bonding; overlap population; MAX phases; metal hydrides; Fysik; Physics; Fysik;

   Sammanfattning : This thesis is divided into two parts. In the first part we study thermodynamics of the two-dimensional Heisenberg ferromagnet with dipolar interaction. This interaction breaks the conditions of the Mermin-Wagner theorem, resulting in a finite transition temperature. LÄS MER