Magnetic behaviour of Eu_2CuSi_3: Large negative magnetoresistance above Curie temperature

TL;DR

This study investigates Eu_2CuSi_3, revealing ferromagnetic ordering below 37 K and a significant negative magnetoresistance near and above the Curie temperature, relevant to colossal magnetoresistance research.

Contribution

First report of negative magnetoresistance in Eu_2CuSi_3, a Cu-containing magnetic rare-earth compound, with detailed magnetic and transport measurements.

Findings

Eu ions are divalent and order ferromagnetically below 37 K.

Negative magnetoresistance observed near and above T_C, peaking at T_C.

Magnetoresistance magnitude increases as temperature decreases.

Abstract

We report here the results of magnetic susceptibility, electrical-resistivity, magnetoresistance (MR), heat-capacity and ^{151}Eu Mossbauer effect measurements on the compound, Eu_2CuSi_3, crystallizing in an AlB_2-derived hexagonal structure. The results establish that Eu ions are divalent, undergoing long-range ferromagnetic-ordering below (T_C=) 37 K. An interesting observation is that the sign of MR is negative even at temperatures close to 3T_C, with increasing magnitude with decreasing temperature exhibiting a peak at T_C. This observation, being made for a Cu containing magnetic rare-earth compound for the first time, is of relevance to the field of collosal magnetoresistance.