Magnetic anomalies in Gd6Co1.67Si3 and Tb6Co1.67Si3

TL;DR

This study investigates the magnetic properties of Gd6Co1.67Si3 and Tb6Co1.67Si3, revealing unique magnetization behaviors and entropy changes, with implications for understanding their magnetic phase transitions.

Contribution

It provides detailed magnetization analysis of these compounds, highlighting the staircase magnetization in Tb and confirming the H^2/3 dependence of entropy change.

Findings

Tb compound shows staircase M(H) at 1.8 K, absent in Gd.

Gd compound's magnetization is non-hysteretic.

Entropy change follows H^2/3 dependence.

Abstract

The compounds, Gd6Co1.67Si3 and Tb6Co1.67Si3, recently reported to form in a Ce6Ni2Si3-derived hexagonal structure (space group: P6_3 / m) and to order magnetically below 295 and 190 K respectively, have been investigated by detailed magnetization (M) studies in the temperature interval 1.8-330 K as a function of magnetic field (H). The points of emphasis are: We observe multiple steps in the M(H) curve for the Tb compound at 1.8 K while increasing H, but these steps do not appear in the reverse cycle of H. At higher temperatures, such steps are absent. However, this 'staircase' behavior of M(H) is not observed for the Gd compound at any temperature and the isothermal magnetization is not hysteretic unlike in Tb compound. From the M(H) data measured at close intervals of temperature, we have derived isothermal entropy change (Delta S) and it is found that Delta S follows a theoretically predicted H^2/3-dependence.