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

Abstract

We study the pyrochlore series ( Eu 1 − x Bi x ) 2 Ir 2 O 7 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 T 2 to T 3 / 2 , suggesting the possibilities of myriad different electronic phases between Eu 2 Ir 2 O 7 and Bi 2 Ir 2 O 7 .