Tuning the semimetallic charge transport in the Weyl semimetal candidate Eu₂Ir₂O₇(111) epitaxial thin film with an all-in-all-out spin structure

We report the stoichiometric epitaxial growth of the Eu₂Ir₂O₇(111) thin film on YSZ substrate by a two-step solid phase epitaxy (SPE) method. An optimized post-annealing environment of the SPE was superior over the conventional air annealing procedure to get rid of the typical impurity phase, Eu₂O₃. The thickness-dependent structural study on Eu₂Ir₂O₇(111) thin films suggests a systematic control of Ir/Eu stoichiometry in our films, which is otherwise difficult to achieve. In addition, the low-temperature electrical resistivity studies strongly support the claim. The power-law dependence analysis of the resistivity data exhibits a power exponent of 0.52 in 50 nm sample suggesting possible disorder-driven semimetallic charge transport in the 3D Weyl semimetallic (WSM) candidate Eu₂Ir₂O₇. In addition, the all-in-all-out/all-out-all-in antiferromagnetic domains of Ir⁴⁺sublattice is verified using the field cooled magnetoresistance measurements at 2 K. Hall resistivity analysis indicate semimetallic hole carrier type dominance near the Fermi level up to the measured temperature range of 2-120 K. Altogether, our study reveals the ground state of stoichiometric Eu₂Ir₂O₇(111) thin film, with an indirect tuning of the off-stoichiometry using thickness of the samples, which is of interest in the search of the predicted 3D WSM phase.