Direct writing of CoFe alloy nanostructures by focused electron beam induced deposition from a heteronuclear precursor

摘要

Recently, focused electron beam induced deposition has been employed toprepare functional magnetic nanostructures with potential in nanomagnetic logicand sensing applications by using homonuclear precursor gases like Fe(CO)5 orCo2(CO)8. Here we show that an extension towards the fabrication of bi-metalliccompounds is possible by using a single-source heteronuclear precursor gas. Wehave grown CoFe alloy magnetic nanostructures from the HFeCo3(CO)12 metalcarbonyl precursor. The compositional analysis indicate that the samplescontain about 80 at% of metal and 10 at% of carbon and oxygen. Four-probemagnetotransport measurements are carried out on nanowires of various sizesdown to a width of 50 nm, for which the room temperature resistivity of43~$\mu\Omega$cm is found. Micro-Hall magnetometry reveals that50~nm$\times$250~nm nanobars of the material are ferromagnetic up to thehighest measured temperature of 250 K. Finally, the TEM microstructuralinvestigation shows that the deposits consist of a bcc Co-Fe phase mixed with aFeCo2O4 spinel oxide phase with nanograins of about 5 nm diameter.