Analytical analysis of a multilayer structure with ultrathin Fe film for magneto-optical sensing

Magneto-optic (MO) response in nanostructures with ultrathin Fe considered for the MO mapping of current pulses with a two-dimensional diffraction limited resolution is investigated in detail. The structures consist of an ultrathin Fe layer sandwiched with dielectric layers, deposited on a reflector and covered by a noble metal protecting layer. The structures are modeled as five-layer systems with abrupt interfaces. Analytical expressions are provided that are useful in the search for the maximum of MO reflected wave amplitude polarized perpendicular to the incident linearly polarized wave, |ryx((05))|. The procedure of finding the maximal |ryx((05))| is illustrated on the structures with ultrathin Fe at the laser wavelength of 632.8 nm. The maximal |ryx((05))| of 0.018347 was achieved in the structure AlN(52 nm)/Fe(15 nm)/AlN(26 nm)/Au. The deposition of a 5 nm protecting Au layer reduced |ryx((05))| by 6 per cent.