Calorimetric study of the superconducting and normal state properties of Ca(Fe1-xCox)2As2

TL;DR

This study investigates the thermal and phase transition properties of Ca(Fe1-xCox)2As2 single crystals, revealing how doping suppresses magnetic order and induces superconductivity, with detailed phase diagram and critical field measurements.

Contribution

It provides the first calorimetric analysis of Ca(Fe1-xCox)2As2, mapping phase transitions and superconducting properties across different doping levels.

Findings

Spin-density wave transition suppressed at higher doping

Superconductivity emerges at x=0.063 with Tc ≈ 14.1 K

Upper critical field Hc2 ≈ 11.5 T

Abstract

We present a calorimetric study on single crystals of Ca(Fe1-xCox)2As2 (x = 0, 0.032, 0.051, 0.056, 0.063, and 0.146). The combined first order spin-density wave/structural transition occurs in the parent CaFe2As2 compound at 168 K and gradually shifts to lower temperature for low doping levels (x = 0.032 and x = 0.051). It is completely suppressed upon higher doping x = 0.056. Simultaneously, superconductivity appears at lower temperature with a transition temperature around Tc = 14.1 K for Ca(Fe0.937Co0.063)2As2. The phase diagram of Ca(Fe0.937Co0.063)2As2 has been derived and the upper critical field is found to be H(c) c2 = 11.5