Specific heat and magnetic measurements in Nd0.5Sr0.5MnO3, Nd0.5Ca0.5MnO3 and Ho0.5Ca0.5MnO3 samples

TL;DR

This study investigates magnetic and specific heat properties of Nd0.5Sr0.5MnO3, Nd0.5Ca0.5MnO3, and Ho0.5Ca0.5MnO3, revealing phase transitions, magnetic ordering, and Schottky-like anomalies with implications for their electronic structure.

Contribution

First comprehensive analysis of magnetic and specific heat behavior in these manganite compounds, highlighting the relationship between band width and Schottky anomaly temperature.

Findings

Identified ferromagnetic, antiferromagnetic, and charge ordering phases.

Observed Schottky-like anomalies below 10 K.

Peak temperature of Schottky anomaly correlates with conduction band width.

Abstract

We studied the magnetization as a function of temperature and magnetic field in the compounds Nd0.5Sr0.5MnO3, Nd0.5Ca0.5MnO3 and Ho0.5Ca0.5MnO3. It allowed us to identify the ferromagnetic, antiferromagnetic and charge ordering phases in each case. The intrinsic magnetic moments of Nd3+ and Ho3+ ions experienced a short range order at low temperatures. We also did specific heat measurements with applied magnetic fields between 0 and 9 T and temperatures between 2 and 300 K in all three samples. Close to the charge ordering and ferromagnetic transition temperatures the specific heat curves showed peaks superposed to the characteristic response of the lattice oscillations. Below 10 K the specific heat measurements evidenced a Schottky-like anomaly for all samples. However, we could not successfully fit the curves to either a two level nor a distribution of two-level Schottky anomaly. Our results indicated that the peak temperature of the Schottky anomaly was higher in the compounds with narrower conduction band.