Quadratic Magneto-Optic Kerr Effect Investigations of Fe(100) Grown on Ir(100)

Magneto-optic Kerr effect (MOKE) is a widely used tool in surface physics to characterize magnetic thin films and single crystals. In most of its applications, the magneto-optic (MO) coupling is assumed to be linear on magnetization by neglecting the quadratic and higher dependences. However, recent observations have shown that the quadratic dependence cannot be always ignored, particularly in systems like ferromagnetic metal thin films, Heusler alloys, and even in half-metallic ferrimagnets. We have used a rotating field method to extract the QMOKE signal from Fe(100) film grown on (100) surface of a single crystal iridium. Our results show that the QMOKE signal from this system is comparable to the linear MOKE signal. We report the parameters L, b, and c which relate the linear (K) and quadratic (G and Delta G) MO coupling coefficients. The real part of L, b, and c obtained from Fe(100)/Ir(100) are -9.75 +/- 0.03 mdeg, 7.28 +/- 0.09 mdeg, and -5.0 +/- 0.1 mdeg, respectively.