Unusual transport properties of ferromagnetic Heusler alloy Co$_2$TiSn

TL;DR

This study investigates the unusual change from semiconducting to metallic transport in ferromagnetic Co$_2$TiSn, revealing how magnetic ordering influences electron conduction and magnetoresistance.

Contribution

It provides new insights into the transport behavior of Co$_2$TiSn across magnetic phase transition, highlighting the impact of magnetic ordering on electronic properties.

Findings

Transport changes from semiconductor-like to metallic at ferromagnetic transition.

External magnetic field induces negative magnetoresistance near Curie temperature.

Comparison with similar behaviors in UNiSn and manganites enhances understanding.

Abstract

We report results of magnetization, zero field resistivity and magnetoresistance measurements in ferromagnetic Heusler alloy Co$_2$TiSn. There is a striking change in the character of electron transport as the system undergoes the paramagnetic to ferromagnetic transition. In the paramagnetic state the nature of the electron transport is like that of a semiconductor and this changes abruptly to metallic behaviour at the onset of ferromagnetic ordering. Application of external magnetic field tends to suppress this semiconducting like transport leading to a negative magnetoresistance which reaches a peak in the vicinity of Curie temperature. Comparison is made with the similar unusual behaviour observed in other systems including UNiSn and manganites.