Thin films of the spin ice compound Ho₂Ti₂O₇

The pyrochlore compounds Ho₂Ti₂O₇ and Dy₂Ti₂O₇ show an exotic form of magnetism called the spin ice state, resulting from the interplay between geometrical frustration and ferromagnetic coupling. A fascinating feature of this state is the appearance of magnetic monopoles as emergent excitations above the degenerate ground state. Over the past years, strong effort has been devoted to the investigation of these monopoles and other properties of the spin ice state in bulk crystals. Here, we report the fabrication of Ho₂Ti₂O₇ thin films using pulsed laser deposition on yttria-stabilized ZrO₂ substrates. We investigated the structuralproperties of these films by X-ray diffraction, scanning transmission electron microscopy, and atomic force microscopy, and the magnetic properties by vibrating sample magnetometry at 2 K. The films not only show a high crystalline quality, but also exhibit the hallmarks of a spin ice:a pronounced magnetic anisotropy and an intermediate plateau in the magnetization along the [111] crystal direction.