Evidence of spin-density-wave order in RFeAsO from measurements of thermoelectric power

TL;DR

This study investigates the presence of spin-density-wave order in RFeAsO compounds through magneto-thermopower and specific heat measurements, revealing SDW order in parent compounds and its influence on electronic properties.

Contribution

It provides experimental evidence of SDW order in RFeAsO compounds using thermoelectric and specific heat measurements, highlighting the temperature dependence of the chemical potential.

Findings

SDW order confirmed in SmAsFeO and NdAsFeO

Strong correlation between thermoelectric power and specific heat near SDW transition

Magnon-drag significantly contributes to thermoelectric power at low temperatures

Abstract

Data on the magneto-thermopower and specific heat of three compounds belonging to '1111' oxypnictides family are reported. One specimen (SmAsFeO0.8F0.2) is a superconductor with Tc = 53 K, while two others (SmAsFeO and NdAsFeO) are nonsuperconducting parent compounds. Our results confirm that spin density wave (SDW) order is present in SmAsFeO and NdAsFeO. In these two samples a strict connection between the thermoelectric power and electronic specific heat is found in the vicinity of SDW transition, what indicates that the chemical potential of charge carriers strongly depends on temperature in this region. Low temperature data suggest presence of significant contribution magnon-drag to the thermoelectric power.