Observation of non-Fermi liquid behavior in hole doped Eu2Ir2O7

TL;DR

This study reports non-Fermi liquid behavior in hole-doped Eu2Ir2O7, showing a reduced metal-insulator transition temperature and metallicity at low temperatures, attributed to disorder and spin-orbit coupling variations.

Contribution

It provides the first evidence of non-Fermi liquid behavior in hole-doped Eu2Ir2O7 and links it to disorder and spin-orbit coupling effects.

Findings

Metal-insulator transition temperature decreases with hole doping.

Doped compounds violate the Mott-Ioffe-Regel limit.

Non-Fermi liquid behavior observed at low temperatures.

Abstract

The Weyl semimetallic compound Eu2Ir2O7 along with its hole doped derivatives (which is achieved by substituting trivalent Eu by divalent Sr) are investigated through transport, magnetic and calorimetric studies. The metal-insulator transition (MIT) temperature is found to get substantially reduced with hole doping and for 10% Sr doping the composition is metallic down to temperature as low as 5 K. These doped compounds are found to violate the Mott-Ioffe-Regel condition for minimum electrical conductivity and show distinct signature of non-Fermi liquid behavior at low temperature. The MIT in the doped compounds does not correlate with the magnetic transition point and Anderson-Mott type disorder induced localization may be attributed to the ground state insulating phase. The observed non-Fermi liquid behavior can be understood on the basis of disorder induced distribution of spin orbit coupling parameter which is markedly different in case of Ir4+ and Ir5+ ions.