Measurement of magnetic property of FePt granular media at near Curie temperature

• Published in: Journal of magnetism and magnetic materials 2017-02, Vol.423, p.27-33
• Main Authors: Yang, H.Z., Chen, Y.J., Leong, S.H., An, C.W., Ye, K.D., Hu, J.F.
• Format: Article
• Language: English
• Subjects: Anisotropy; Coercivity; Curie temperature; Demagnetization; Ferrous alloys; Heat assisted magnetic recording; Intermetallic compounds; Iron compounds; Laser beam heating; Magnetic properties; Magnetic recording; Magnetic switching; Magnetism; Magneto-optic Kerr effect; Media; Optical properties; Platinum compounds; Switching; Switching field distribution
• ISSN: 0304-8853; 1873-4766
• DOI: 10.1016/j.jmmm.2016.09.071

The characterization of the magnetic switching behavior of heat assisted magnetic recording (HAMR) media at near Curie temperature (Tc) is important for high density recording. In this study, we measured the magnetic property of FePt granular media (with room temperature coercivity ~25kOe) at near Tc with a home built HAMR testing instrument. The local area of HAMR media is heated to near Tc by a flat-top optical heating beam. The magnetic property in the heated area was in-situ measured by a magneto-optic Kerr effect (MOKE) testing beam. The switching field distribution (SFD) and coercive field (Hc) of the FePt granular media and their dependence on the optical heating power at near Tc were studied. We measured the DC demagnetization (DCD) signal with pulsed laser heating at different optical powers. We also measured the Tc distribution of the media by measuring the AC magnetic signal as a function of optical heating power. In a summary, we studied the SFD, Hc of the HAMR media at near Tc in a static manner. The present methodology will facilitate the HAMR media testing. •A flat-top optical beam homogeneously heats up HAMR media to near Tc.•When Hc of media drops to 5kOe with optical heating, SFD is measured to be 0.6.•Hc, SFD, Ms of HAMR media at near Tc are measured with the methodology.