Thickness-dependent quantum transport of Weyl fermions in ultra-high-quality SrRuO3 films

The recent observation of Weyl fermions in the itinerant 4d ferromagnetic perovskite SrRuO3 points to this material being a good platform for exploring novel physics related to a pair of Weyl nodes in epitaxial heterostructures. In this Letter, we report the thickness-dependent magnetotransport properties of ultra-high-quality epitaxial SrRuO3 films grown under optimized conditions on SrTiO3 substrates. Signatures of Weyl fermion transport, i.e., unsaturated linear positive magnetoresistance accompanied by a quantum oscillation having a high quantum mobility of 10 000cm(2)/Vs and a pi Berry phase, were observed in films with thicknesses as small as 10nm. Residual resistivity increased with the decreasing film thickness indicating disorder near the interface between SrRuO3 and the SrTiO3 substrate. Since this disorder affects the magnetic and electrical properties of the films, the Curie temperature decreases and the coercive field increases with the decreasing thickness. Thickness-dependent magnetotransport measurements revealed that the threshold residual resistivity ratio to observe Weyl fermion transport is 21. These results provide guidelines for realizing quantum transport of Weyl fermions in SrRuO3 near heterointerfaces.

Automated summary

The study reveals the significant impact of thickness on Weyl fermion transport in SrRuO3 films, with smaller film thickness leading to higher residual resistivity and changes in magnetic and electrical properties. These findings provide guidelines for achieving quantum transport of Weyl fermions.