Direct measurement of the magnetic anisotropy field in Mn-Ga and Mn-Co-Ga Heusler films

Ciarán Fowley, Siham Ouardi, Takahide Kubota, Oguz Yildirim, Andreas Neudert, Kilian Lenz, Volker Sluka, Jürgen Lindner, Joseph M. Law, Shigemi Mizukami, Gerhard H. Fecher, Claudia Felser, Alina M. Deac

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)

Abstract

The static and dynamic magnetic properties of tetragonally distorted Mn-Ga based alloys were investigated. Static properties are determined in magnetic fields up to 6.5 T using SQUID magnetometry. For the pure Mn1.6Ga film, the saturation magnetisation is 0.36 MA m-1 and the coercivity is 0.29 T. Partial substitution of Mn by Co results in Mn2.6Co0.3Ga1.1. The saturation magnetisation of those films drops to 0.2 MA m-1 and the coercivity is increased to 1 T. The time-resolved magneto-optical Kerr effect (TR-MOKE) is used to probe the high-frequency dynamics of Mn-Ga. The ferromagnetic resonance frequency extrapolated to zero-field is found to be 125 GHz with a Gilbert damping, α, of 0.019. The anisotropy field is determined from both SQUID and TR-MOKE to be 4.5 T, corresponding to an effective anisotropy density of 0.81 MJ m-3. Given the large anisotropy field of the Mn2.6Co0.3Ga1.1 film, pulsed magnetic fields up to 60 T are used to determine the field strength required to saturate the film in the plane. For this, the extraordinary Hall effect was employed as a probe of the local magnetisation. By integrating the reconstructed in-plane magnetisation curve, the effective anisotropy energy density for Mn2.6Co0.3Ga1.1 is determined to be 1.23 MJ m-3.

Original languageEnglish
Article number164006
JournalJournal of Physics D: Applied Physics
Volume48
Issue number16
DOIs
Publication statusPublished - 2015 Apr 29

Keywords

  • Hall effect
  • Heusler films
  • coercivity
  • magnetic anisotropy
  • time-resolved magneto-optical Kerr effect

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Acoustics and Ultrasonics
  • Surfaces, Coatings and Films

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