Magnetic resonance and structural properties of high quality yttrium iron garnet (YIG) thin films deposited by a Chemical solution synthesis

Resumen del trabajo presentado al 14th International Workshop on Magnetism & Superconductivity at the Nanoscale, celebrado en Coma-Ruga, El Vendrell (España) del 1 al 6 de julio de 2018.
In this work we show the fabrication of epitaxial Y3Fe5O12 (YIG) thin films on Gd3Ga5O12 (111) (GGG) substrates by means of Polymer Assisted Deposition (PAD). Cubic YIG is a well known and characterized ferrimagnetic material at room temperature, with excellent magneto-optical properties, high electrical resistivity, and a very narrow ferromagnetic resonance, which makes it particularly suitable for applications in filters and resonators at microwave frequencies such us in potential devices based on spintronics, magnonics and spin caloritronics. In the case of YIG, the Fe3+ sublattices order antiferromagnetically, with nonmagneticY3+ ions located at the dodecahedral sites. Therefore, it is the uncompensated Fe3+ at a tetrahedral site which is responsible for the ferrimagnetic state at room temperature, up to a Curie temperature ∼560K. Thus, it is upon the precise stoichiometry and distribution of Fe3+ ions among the octahedral/tetrahedral sites of this complex structure, where relies the emergence of all these interesting properties, which to date has normally hampered the production of high-quality YIG thin films by affordable chemical methods. The standard method for YIG single-crystal fabrication, liquid phase epitaxy, and other bulk synthetic are not suitable methods to fabricate samples down to the nanometer range. Even when this problem has been overcome by using physical techniques such as pulsed laser deposition or sputtering, chemical solution deposition offers important advantages regarding affordability and scalability for thin-film fabrication. Here we report the chemical solution synthesis of YIG thin films, with excellent chemical, crystalline, and magnetic homogeneity. The films show a very narrow ferromagnetic resonance (long spin relaxation time), comparable to that obtained from high vacuum physical deposition methods. These results demonstrate that chemical methods can compete to develop nanometer-thick YIG films with the quality required for spintronic based devices and other high-frequency applications.