Anomalous lattice contraction and emergent electronic phases in Bi-doped Eu2Ir2O7

We study the pyrochlore series (Eu1-xBix)2Ir2O7 for 0≤x≤1. We show that for small x, the lattice undergoes an anomalous contraction but the time reversal symmetry breaking all-in/all-out state remains robust and the resistivity approaches a 1/T dependence at low T, suggesting proximity to the Weyl semimetallic phase. At the boundary near 10% Bi doping, a qualitatively different ground state emerges, which is characterized by a metallic behavior and the absence of magnetic ordering at least down to 0.02 K. For higher Bi doping, the resistivity remains metallic, and evolves gradually from T linear to T2 to T3/2, suggesting the possibilities of myriad different electronic phases between Eu2Ir2O7 and Bi2Ir2O7.