Iridium Oxides have been proven to be very useful in spintronics. Indeed, a decade ago, IrO2 was proposed as the most promising material for spin-current detectors; thanks to its s strong spin-orbit coupling and concomitant large spin Hall effect. Doping this material with magnetic elements opens the possibility of tuning its electrical and magnetic behavior and/or the efficiency of the conversion between charge currents and spin currents, of interest for several spintronic applications. In this work we have explored the role of Co doping on the structural and magnetic properties of IrO2 thin films. Ir1-xCoxO2 (x = 0.07–0.6) 80 nm thin films were prepared by reactive magnetron co-sputtering and analyzed using X ray reflectivity and diffraction, Scanning Electron Microscopy and SQUID magnetometry. We’ve found that, regardless of the doping, the rutile-like crystal structure of IrO2 was maintained; with only gradual cell contraction and grain size reduction as doping increases. On the other hand, and despite the high Co doping achieved, no ferromagnetism was observed in any of the samples. From this, one can infer that cobalt takes a Co3+ oxidation state in a low spin configuration, inducing a change of oxidation state of the iridium ions from Ir4+ to Ir5+. This is expected to result in a higher spin-orbit coupling and, therefore, making Ir1-xCoxO2 thin films promising candidates for devices with optimum conversion between charge currents and spin currents.

Resumen del trabajo presentado a la XII Reunión del grupo de física de la materia condensada de la RSEF (GEFES), celebrada en Salamanca del 1 al 3 de febrero de 2023.

Peer reviewed