100 50 0 -20 -15 -10 -5 0 Intensity (arb. units) 781 780 779 778 777 Photon Energy (eV) 0.5 0.4 0.3 0.2 0.1 0 Magnetization ( GLYPH<s109> B /Co) 6 4 2 0 Magnetic Field (T) Co 2 p$_{3/2}$ XAS XMCD P$_{O2}$ =10$^{-2}$ Pa As grown 4.5 T 7.0 T Annealed 4.5 T 7.0 T T =20 K Zn$_{0.9}$Co$_{0.1}$O  As-grown  Annealed — Fitted T  = 20 K Zn$_{0.9}$Co$_{0.1}$O (a) (b) FIG. 5: (Color online) Annealing effects on the XMCD spectra of the Zn$_{0}$$_{.}$$_{9}$Co$_{0}$$_{.}$$_{1}$O thin film de- posited at P$_{O2}$ = 10 − 2 Pa. (a) Comparison of the H dependent XMCD spectra between the as-grown and annealed samples. (b) H dependence of the magnetization of the same samples de- duced from the XMCD spectra. The H dependences have been fitted to linear functions χH + M$_{s}$ . 20