H.J. Mamin, B.A. Gurney, et al.
Applied Physics Letters
The coercivity Hand coercive squareness S* of γ - FeO films made by oxidation of reactive-sputtered, Os-doped Fe0, change by as much as 30 and 50%, respectively, in one day at room temperature. On initial measurement the films are isotropic in the plane and have S* values of 0.5 to 0.7. Along the direction of remanence an easy axis develops with a 10 to 30% higher Hand an S* of 0.85 to 0.95, corresponding to a global anisotropy in the range of 5 × 104erg/cm3. Reversible changes happen so rapidly that one can see large differences on consecutive VSM loops. These films also exhibit very high susceptibility (x > 10-3G/Oe) and rotational hysteresis (W> 105erg/cm3) at 16 kOe, suggesting random local anisotropy with components in excess of 50 kOe. Rotational hysteresis has a strong dependence on the rate of field rotation. In a stationary field the torque decreases initially logarithmically with time, yielding activation energies varying from 0.6 to 0.16 eV as the temperature increases from 24 to 120°C. All iron oxide films made by oxidation of reactive-sputtered Fe0, whether undoped or Co- or Os-doped, show both large W and global anisotropy reversible at room temperature. In fact these features are already present in as-deposited, undoped FeO. © 1989 IEEE
H.J. Mamin, B.A. Gurney, et al.
Applied Physics Letters
J.X. Shen, R.D. Kirby, et al.
Journal of Applied Physics
J. Heidmann, T.A. Nguyen, et al.
Journal of Applied Physics
D.D. Tang, P.-K. Wang, et al.
IEDM 1995