# Schottky anomaly and short-range antiferromagnetic correlations in filled skutterudites Pr$_{1-x}$Eu$_x$Pt$_4$Ge$_{12}$

## TL;DR

This study investigates how Eu substitution affects magnetic correlations and Schottky anomalies in filled skutterudites, revealing the interplay between external magnetic fields, antiferromagnetic ordering, and short-range magnetic correlations.

## Contribution

It provides new insights into the magnetic behavior and Schottky anomalies in Eu-doped PrPt4Ge12, highlighting the effects of external magnetic fields on magnetic ordering and correlations.

## Key findings

- Schottky anomalies persist across all doping levels.
- External magnetic fields shift Schottky peaks differently depending on Eu content.
- Short-range AFM correlations are induced by Eu magnetic moments.

## Abstract

By performing a series of thermodynamic measurements in an applied magnetic field $H_{\textrm{ext}}$, we investigated the effects of Eu substitution on the Pr sites in filled skutterudite compound Pr$_{1-x}$Eu$_x$Pt$_4$Ge$_{12}$ ($ 0 \leq x \leq 1$). A heat capacity Schottky anomaly is present over the whole doping range. For the samples with $x > 0.5$, these Schottky anomaly peaks shift to lower temperature with increasing $H_{\textrm{ext}}$. We argue that this behavior reflects the antiferromagnetic (AFM) ordering of the Eu moments, as the AFM transition is suppressed by $H_{\textrm{ext}}$. The Schottky peaks in the samples with $x \leq 0.5$ shift to higher temperatures with increasing magnetic field, signaling the presence of an internal magnetic field due to short-range AFM correlations induced by magnetic moments of neighboring Eu sites. In low $H_{\textrm{ext}}$, the Schottky gaps show a non-linear relationship with $H_{\textrm{ext}}$ as the magnetic moments become weakly magnetized. In high $H_{\textrm{ext}}$, the magnetic moments of Eu sites become completely aligned with $H_{\textrm{ext}}$. Thus, increasing $H_{\textrm{ext}}$ does not further increase the magnetization, hence the Schottky gaps increase linearly with $H_{\textrm{ext}}$