# Electronic structure and $H$-$T$ phase diagram of Eu(Fe$_{1-x}$Rh$_x$)$_2$As$_2$

## TL;DR

This study explores the electronic structure and magnetic-superconducting phase diagram of Eu(Fe$_{1-x}$Rh$_x$)$_2$As$_2$, revealing how localized Eu magnetism coexists and interacts with superconductivity, using ARPES and thermodynamic measurements.

## Contribution

It provides new insights into the coexistence and competition of magnetic order and superconductivity in EuFe$_2$As$_2$ family through combined experimental techniques.

## Key findings

- Reentrant superconductivity due to magnetic interactions.
- Electronic structure modifications near optimal Rh doping.
- Evidence of magnetic influence on the superconducting state.

## Abstract

The iron-based superconductors represent a promising platform for high-temperature superconductivity, but the interactions underpinning their pairing present a puzzle. The EuFe$_2$As$_2$ family is unique among these materials for having magnetic order which onsets within the superconducting state, just below the superconducting transition. Superconductivity and magnetic order are normally antagonistic and often vie for the same unpaired electrons, but in this family the magnetism arises from largely localized Eu moments and they coexist, with the competition between these evenly-matched opponents leading to reentrant superconducting behavior. To help elucidate the physics in this family and the interactions between the magnetic order and superconductivity, we investigate the $H$--$T$ phase diagram near optimal Rh doping through specific heat, resistivity, and magnetization measurements, and study the electronic structure by angular-resolved photoemission spectroscopy. The competition between the Eu and FeAs layers may offer a route to directly accessing the electronic structure under effective magnetic fields via ARPES, which is ordinarily a strictly zero-field technique.