Thermal properties of SmFeAs(O1-xFx) as probe of the interplay between electrons and phonons

TL;DR

This study investigates how F-doping affects the thermal properties of SmFeAsO, revealing that doping suppresses SDW order and induces superconductivity, while phonons remain largely unaffected, highlighting their role in probing electronic ground states.

Contribution

It provides a comparative analysis of thermal properties across different F-doping levels, showing phonons can probe electronic ground state features without significant alteration by doping.

Findings

SDW order is suppressed with F-doping

Superconducting features emerge at optimal doping

Phonons remain largely unaffected by F-doping

Abstract

A comparative study of thermal properties of SmFeAsO, SmFeAs(O0.93F0.07) and SmFeAs(O0.85F0.15) samples is presented. Specific heat and thermal conductivity show clear evidences of the spin density wave (SDW) ordering below TSDW 135 K in undoped SmFeAsO. At low level of F-doping, SmFeAs(O0.93F0.07), SDW ordering is suppressed and superconducting features are not yet optimally developed in both specific heat and thermal conductivity. At optimal level of F-doping SmFeAs(O0.85F0.15) anomalies related to the superconducting transition are well noticeable. By a compared analysis of doped and undoped samples we conclude that, despite F-doping modifies definitely the electronic ground state, it does not substantially alter phonon and electron parameters, like phonon modes, Sommerfeld coefficient, electro-phonon coupling. The analysis of the thermal conductivity curves provides an evaluation of SDW and superconducting energy gap, showing that phonons can suitably probe features of electronic ground state.