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- Unikandanunni, Vivek, et al.
(författare)
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Anisotropic ultrafast spin dynamics in epitaxial cobalt
- 2021
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 118:23
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the ultrafast spin dynamics in an epitaxial hcp(11⎯⎯00) cobalt thin film. By performing pump-probe magneto-optical measurements with the magnetization along either the easy or hard magnetic axis, we determine the demagnetization and recovery time for the two axes. We observe an average of 33% slower dynamics along the easy magnetization axis, which we attribute to magneto-crystalline anisotropy of the electron-phonon coupling, supported by our ab initio calculations. This points toward an unambiguous and previously undisclosed role of anisotropic electron–lattice coupling in ultrafast magnetism.
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2. |
- Unikandanunni, Vivek, et al.
(författare)
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Inertial spin dynamics : the role of magneto-crystalline anisotropy
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We investigate the spin dynamics driven by terahertz magnetic fields in epitaxial thin films of cobalt in its three crystalline phases with distinct magneto-crystalline anisotropy. The terahertz magnetic field generates a torque on the magnetization which causes it to precess for about 1 ps, with a sub-picosecond temporal lag from the driving force. Then, the magnetization undergoes natural damped oscillations in the THz range at a characteristic frequency of the crystalline phase, containing higher-order harmonics of the fundamental. We describe the experimental observations solving the inertial Landau-Lifshitz-Gilbert equation. Using the results from the relativistic theory of magnetic inertia, we find that the angular momentum relaxation time η is the only material parameter needed to describe all the experimental evidence. Our experiments suggest a correlation between η and the strength of the magneto-crystalline anisotropy
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3. |
- Unikandanunni, Vivek, 1993-, et al.
(författare)
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Inertial Spin Dynamics in Epitaxial Cobalt Films
- 2022
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 129:23
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the spin dynamics driven by terahertz magnetic fields in epitaxial thin films of cobalt in its three crystalline phases. The terahertz magnetic field generates a torque on the magnetization which causes it to precess for about 1 ps, with a subpicosecond temporal lag from the driving force. Then, the magnetization undergoes natural damped THz oscillations at a frequency characteristic of the crystalline phase. We describe the experimental observations solving the inertial Landau-Lifshitz-Gilbert equation. Using the results from the relativistic theory of magnetic inertia, we find that the angular momentum relaxation time η is the only material parameter needed to describe all the experimental evidence. Our experiments suggest a proportionality between η and the strength of the magnetocrystalline anisotropy.
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