Effects of pressure and magnetic field on the reentrant superconductor Eu(Fe0.93Rh0.07)2As2

Abstract

Electron-doped Eu(Fe0.93Rh0.07)2As2 has been systematically studied by high-pressure investigations of the magnetic and electrical transport properties in order to unravel the complex interplay of superconductivity and magnetism. The compound reveals an exceedingly broad reentrant transition to the superconducting state between Tc,on=19.8 K and Tc,0=5.2 K due to a canted A-type antiferromagnetic ordering of the Eu2+ moments at TN=16.6 K and a reentrant spin glass transition at TSG=14.1 K. At ambient pressure evidences for the coexistence of superconductivity and ferromagnetism could be observed, as well as a magnetic-field-induced enhancement of the zero-resistance temperature Tc,0 up to 7.2 K with small magnetic fields applied parallel to the ab plane of the crystal. We attribute the field-induced-enhancement of superconductivity to the suppression of the ferromagnetic component of the Eu2+ moments along the c axis, which leads to a reduction of the orbital-pair-breaking effect. Application of hydrostatic pressure suppresses the superconducting state around 14 kbar along with a linear temperature dependence of the resistivity, implying that a non-Fermi liquid region is located at the boundary of the superconducting phase. At intermediate pressure, an additional feature in the resistivity curves is identified, which can be suppressed by external magnetic fields and competes with the superconducting phase. We suggest that the effect of negative pressure by the chemical Rh substitution in Eu(Fe0.93Rh0.07)2As2 is partially reversed, leading to a reactivation of the spin density wave.

Source-reported materials — not catalogue approval

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