Enhanced Magnetism in SrRuO$_{3}$ Thin Film by SrTiO$_{3}$ Capping Monolayers

Substrate induced mechanical strain is known to reduce the magnetism in itinerant ferromagnetic SrRuO$_{3}$ thin films. Here we show that monolayers of SrTiO$_{3}$ epitaxial capping film can be used to enhance the magnetism in ultra-thin SrRuO$_{3}$ films. For a device with a 6 monolayer thick SrRuO$_{3}$ film, a 2 monolayer thick SrTiO$_{3}$ capping layer can boost SrRuO$_{3}$'s magnetic Curie temperature by 15 Kelvin. Unlike thick substrates, the monolayers-thick SrTiO$_{3}$ capping layer can be patterned using standard lithography methods for making complex oxide electronic devices. We demonstrate a SrRuO$_{3}$ film device with regions of different Curie temperatures by patterning the SrTiO$_{3}$ capping layer.