Interval Identification of FMR Parameters for Spin Reorientation Transition in (Ga,Mn)As

In this work we report results of ferromagnetic resonance studies of a 6% 15 nm (Ga,Mn)As layer, deposited on (001)-oriented GaAs. The measurements were performed with in-plane oriented magnetic field, in the temperature range between 5 K and 120 K. We observe a temperature induced reorientation of the effective in-plane easy axis from [(1) over bar 10] to [110] direction close to the Curie temperature. The behavior of magnetization is described by anisotropy fields, H-eff (= 4 pi M - H-2 perpendicular to), H-2 parallel to, and H-4 parallel to. In order to precisely investigate this reorientation, numerical values of anisotropy fields have been determined using powerful - but still largely unknown - interval calculations. In simulation mode this approach makes possible to find all the resonance fields for arbitrarily oriented sample, which is generally intractable analytically. In "fitting" mode we effectively utilize full experimental information, not only those measurements performed in special, distinguished directions, to reliably estimate the values of important physical parameters as well as their uncertainties and correlations