Study of Electron Spin Resonance on single crystals $EuFe_{2-x}Co_{x}As_2$

Abstract

The temperature dependence of electron spin resonance (ESR) was studied in EuF e2−xCoxAs2 (x = 0.0 ,0.067 ,0.1 ,0.2 ,0.25 ,0.285 ,0.35 ,0.4 and 0.5). The ESR spectrum of all the samples indicates that the g factor and peak-to-peak linewidth strongly depend on the temperature. Moreover, the peak-to-peak linewidth shows the Korringa behavior, indicating an exchange coupling between the conduction electrons and the Eu 2+ ions. The linewidth, g factor and the integrate ESR intensity show anomalies at the temperature of the spin-density-wave (SDW). The linewidth below the SDW transition does not rely on the temperature. This gives the evidence of the gap opening at the TSDW . The slope of the linewidth is closely associated to TSDW and TC. This exotic behavior may be related to the nesting of the Fermi surface.

Coupling of localized moments and itinerant electrons in EuFe2As2 single crystals studied by Electron Spin Resonance

“…Note. While finalizing this paper we became aware of an ESR study of Co doped EuFe 2 As 2 for temperatures above 110 K, which shows a Korringa relaxation in agreement with our measurements [33].…”