Magnetic Anisotropy and Crystal Domain Variant in <inline-formula> <tex-math notation="LaTeX">$ {L} 1_{{0}}$ </tex-math> </inline-formula>-FePt Polycrystalline Films

Novel torque magnetometry for uniaxial anisotropy constants of thin films and its application to FePt granular thin films

“…The dashed line shows the assumed K u trend calculated using the FePt volume fraction and the K u values of 10nm-thick polycrystalline FePt films, which were fabricated using a process identical to that used in our experiment. 8,22) K u followed the assumed K u trend well with increasing C content up to 34 vol % C, although that the K u value of the FePt-40 vol % C film deviated from the trend. Because the 10-nm-thick FePt film was well L1 0 -ordered, unlike the 4-nm-thick FePt film, 22) the results suggest that granulation by carbon addition of less than 34 vol % did not disturb the L1 0 ordering of the FePt grains and that the intrinsic K u remained around 3 MJ=m 3 .…”

“…3,4) In particular, many studies have examined thin films that show large perpendicular K u values of more than 10 6 J=m 3 , for example, L1 0 -FePt. [5][6][7][8] Although accurate estimation of K u is necessary, no standard technique exists. Some reports have described the use of a saturation field, H s , instead of an anisotropic field, H k , in calculations of K u .…”