Antiferromagnetic transition in EuFe$_2$As$_2$: A possible parent compound for superconductors

TL;DR

This study investigates EuFe$_2$As$_2$, revealing two magnetic transitions and suggesting it as a potential parent compound for superconductivity upon doping, based on comprehensive physical property measurements.

Contribution

It provides detailed experimental evidence of magnetic phase transitions in EuFe$_2$As$_2$, highlighting its potential as a superconducting parent compound similar to other iron arsenides.

Findings

Two magnetic phase transitions at 200 K and 20 K

Spin-density-wave-like antiferromagnetic transition at 200 K

Eu$^{2+}$ moments order antiferromagnetically at 20 K

Abstract

Ternary iron arsenide EuFe$_2$As$_2$ with ThCr$_2$Si$_2$-type structure has been studied by magnetic susceptibility, resistivity, thermopower, Hall and specific heat measurements. The compound undergoes two magnetic phase transitions at about 200 K and 20 K, respectively. The former was found to be accompanied with a slight drop in magnetic susceptibility (after subtracting the Curie-Weiss paramagnetic contribution), a rapid decrease in resistivity, a large jump in thermopower and a sharp peak in specific heat with decreasing temperature, all of which point to a spin-density-wave-like antiferromagnetic transition. The latter was proposed to be associated with an A-type antiferromagnetic ordering of Eu$^{2+}$ moments. Comparing with the physical properties of the iso-structural compounds BaFe$_2$As$_2$ and SrFe$_2$As$_2$, we expect that superconductivity could be induced in EuFe$_2$As$_2$ through appropriate doping.