<i>In-situ</i> fabrication and transport properties of (111) Y2Ir2O7 epitaxial thin film

Abstract

We report on the successful fabrication of (111) oriented thin films of pyrochlore iridate Y2Ir2O7 by means of solid phase epitaxy. Essentially, we developed an entirely in situ annealing protocol, which is superior to the conventional ex-situ routine that requires multi-hour annealing to stabilize the proper pyrochlore structure. The morphological quality of the films has been confirmed by x-ray diffraction, reflectivity, and reciprocal space mapping, demonstrating their high crystallinity with a pure pyrochlore phase and an expected epitaxial relation to the substrate. Strikingly, below the magnetic phase transition, the temperature dependence of resistivity shows a power-law behavior with the power exponent of ∼3/2, characteristic of a Weyl semimetal in the presence of impurities and electron–electron correlations. Below 10 K, the magneto-transport measurements reveal the emergence of a non-saturated negative magnetoresistance up to 9 T with a small “valley” around zero field. These findings are further interpreted in relation to the weak anti-localization effect and the non-collinear antiferromagnetic ordering on the Ir sublattice.