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Inertial Spin Dynamics in Epitaxial Cobalt Films

Research output: Contribution to Journal/MagazineJournal articlepeer-review

  • V. Unikandanunni
  • R. Medapalli
  • M. Asa
  • E. Albisetti
  • D. Petti
  • R. Bertacco
  • E.E. Fullerton
  • S. Bonetti
Article number237201
<mark>Journal publication date</mark>2/12/2022
<mark>Journal</mark>Physical review letters
Issue number23
Publication StatusPublished
Early online date29/11/22
<mark>Original language</mark>English


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.

Bibliographic note

Export Date: 21 December 2022 Funding details: U.S. Department of Energy, USDOE Funding details: Office of Science, SC Funding details: Basic Energy Sciences, BES, DE-SC0003678 Funding details: European Research Council, ERC, 715452 Funding text 1: V. U. and S. B. acknowledge support from the European Research Council, Starting Grant No. 715452 “MAGNETIC-SPEED-LIMIT.” R. M. and E. E. F. were supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-SC0003678.