  We present the depth-resolved nuclear resonance reflectivity (NRR) studies of
the magnetization evolution in [57Fe(3 nm)/Cr(1.2 nm)]*10 multilayer under the
applied external field. The measurements have been performed at the station
BL09XU of SPring-8 at different values of the external field (from 0 up to 1500
Oe). We apply the joint fit of the delayed reflectivity curves and the time
spectra of the nuclear resonance reflectivity measured at different grazing
angles for enhancement of the depth resolution and reliability of the results.
For the first time we show that the azimuth angle, which is used in all papers
devoted to the magnetization profile determination, has more complicated
physical sense due to the partially coherent averaging of the scattering
amplitudes from magnetic lateral domains. We describe the way how to select the
true azimuth angle from the determined "effective azimuth angle". Finally we
obtain the noncollinear twisted magnetization depth-profiles where the spin
flop state appears sequentially in different 57Fe layers at increasing applied
field.
