Inverse garnet/Pt heterostructures by lateral crystallization

Abstract

Rare-earth iron garnet thin films are widely used in magnonics and spintronics because of their insulating nature and unique magnetic properties, such as low Gilbert damping and a tunable magnetic anisotropy. However, these properties are mostly restricted to single-crystalline films grown on specific substrates like Gd3⁢Sc2⁢Ga3⁢O12 (GSGG), limiting their applications. Lateral crystallization is a powerful technique enabling the design of new garnet heterostructures, with the potential to overcome these limitations. We demonstrate the crystallization of a thulium iron garnet film on top of a thin Pt layer, which is deposited on a GSGG substrate. Hereby, a hole pattern in the Pt layers acts as a crystallization seed, resulting in a single-crystalline garnet film extending onto the Pt layer. The hole pattern in combination with a lateral crystallization rate of about 18⁢nm/min allows crystallization of large areas by post-deposition annealing at 700°⁢C for a few hours. The resulting garnet film exhibits properties comparable to epitaxially grown films without an interlayer, with a Gilbert damping as low as 0.008. Therefore, lateral crystallization of garnet thin films can open up new possibilities for designing high-quality garnet/metal heterostructures, in particular for spintronic applications.