In this work, we describe an experimental setup for a spatially resolved pump-probe experiment with an integrated wide-field magneto-optical (MO) microscope. The MO microscope can be used to study ferromagnetic materials with both perpendicular-to-plane and in-plane magnetic anisotropy via polar Kerr and Voigt effects, respectively. The functionality of the Voigt effect-based microscope was tested using an in-plane magnetized ferromagnetic semiconductor (Ga,Mn)As. It was revealed that the presence of mechanical defects in the (Ga,Mn)As epilayer alters significantly the magnetic anisotropy in their proximity. The importance of MO experiments with simultaneous temporal and spatial resolutions was demonstrated using a (Ga,Mn)As sample attached to a piezoelectric transducer, which produces a voltage-controlled strain. We observed a considerably different behavior in different parts of the sample that enabled us to identify sample parts where the epilayer magnetic anisotropy was significantly modified by the presence of the piezoelectric transducer and where it was not. Finally, we discuss the possible applicability of our experimental setup for the research of compensated antiferromagnets, where only MO effects even in magnetic moments are present.
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To match the maximum of the MO spectrum of the sample shown in Fig. 2(d), the central laser wavelength of 774 nm and filters F1 (Thorlabs, NF785-33) and F2 (Thorlabs, FBH780-10) were chosen. Other combinations of central laser wavelength and filters can be used to cover different spectral regions. The filtering of the original laser pulse spectral content leads to a prolongation of the laser pulses. To address this, we have performed the intensity autocorrelation measurements both without and with the filters. We observed that the insertion of the filters leads to a prolongation of the autocorrelation trace from 150 to 320 fs (full width at half maximum), which corresponds to the temporal resolution of our pump-probe experiments.
