Highly textured FeCo thin films deposited by low temperature pulsed laser deposition.

Nowadays, the wide number of technological applications of magnetic materials requires not only strict control on their chemical and physical properties but also an always increasing capability to properly tailor them to optimize the devices' performance. Among the ferromagnetic materials, the FeCo alloy is one of the most studied for its peculiar combination of high saturation magnetization (1.95 MA/m), high Curie temperature (1250 K), high permeability (up to 5000), and good mechanical properties [1,2]. These properties determine the high versatility of this material and the possibility to use it in different applications, including spintronics devices [3], magnetic recording [4] and permanent magnets [5]. In this work [6], we present a study of Fe50Co50 thin films deposited on MgO (100) substrates by the Pulsed Laser Deposition technique, which has been successfully exploited for the deposition of both complex oxide materials [7] and metallic alloys [8], paving the way for a simpler process to fabricate a new class of advanced multifunctional films and heterostructures made of different materials. The effect of the deposition temperature on the crystallographic orientation was studied by means of XRD and HRTEM analysis and correlated to the anisotropic properties measured by angle dependent hysteresis loops. Highly textured films with a bcc structure and very smooth surface were obtained even at room temperature, the film being [100] and [110] oriented at Tdep = 25 °C and 150 °C, respectively. The cubic symmetry is reflected in the angular dependence of remanent magnetization, showing a 4-fold character, whose in-plane distribution is consistent with the different crystallographic orientations of the films (Fig. 1). The high structural quality, even at room temperature, is reflected in a high value of the saturation magnetization (~1.88 MA/m) and low coercivity (~2 mT at 25 °C and ~4 mT at 150 °C), along the easy-axis), matching the requirements for technological applications.