Broadband ferromagnetic resonance of ultrathin yttrium iron garnet films by pulsed laser deposition: Effects of deposition parameters

Abstract

In this study, we investigate the growth and characteristics of ultrathin ferrimagnetic yttrium iron garnet (YIG, Y3Fe5O12) films on a Gallium Gadolinium Garnet (GGG) substrate using the pulsed laser deposition technique (PLD). We aim to improve the magnetic quality of the films by varying the deposition parameters, specifically the laser energy and oxygen pressure. We conduct broadband ferromagnetic resonance (FMR) measurements to characterize the magnetic properties and Gilbert damping of the films. Our findings demonstrate that adjusting the deposition parameters systematically controls the saturation magnetization and Gilbert damping of YIG films. Our measurements show that in the absence of oxygen, the films exhibit higher-than-expected values of magnetization and Gilbert damping, suggesting that the films have a higher Fe concentration. Conversely, when introducing oxygen in the chamber, we observe a decrease in the magnetization and damping values, approaching those of bulk YIG films. Notably, we achieve a saturation magnetization of 0.185 T and an ultra-low Gilbert damping of 1.7 ×10−4 for films deposited under conditions of high laser energy and oxygen pressure. This is mainly due to a better Y:Fe ratio approaching the stoichiometric value of 0.6 as the oxygen pressure increased. Our findings provide valuable insights for preparing high-quality ferrimagnetic films suitable for various magnonics applications and spin Hall devices.