Structural and magneto-transport characterization of Co_2Cr_xFe_(1-x)Al Heusler alloy films

TL;DR

This study explores the structure and magneto-transport properties of Co_2Cr_xFe_(1-x)Al Heusler alloy films, demonstrating their potential in spintronic devices with high Curie temperatures and significant magnetoresistance.

Contribution

It provides new insights into the growth, magnetic behavior, and magnetoresistance of Co_2Cr_xFe_(1-x)Al films on different substrates, including their integration into magnetic tunnel junctions.

Findings

Films are magnetically soft and ferromagnetic with Curie temperatures up to 630 K.

Polycrystalline films on MgO show 37% magnetoresistance at room temperature.

Magnetic moments are reduced compared to bulk but comparable to elevated temperature growth films.

Abstract

We investigate the structure and magneto-transport properties of thin films of the Co_2Cr_xFe_(1-x)Al full-Heusler compound, which is predicted to be a half-metal by first-principles theoretical calculations. Thin films are deposited by magnetron sputtering at room temperature on various substrates in order to tune the growth from polycrystalline on thermally oxidized Si substrates to highly textured and even epitaxial on MgO(001) substrates, respectively. Our Heusler films are magnetically very soft and ferromagnetic with Curie temperatures up to 630 K. The total magnetic moment is reduced compared to the theoretical bulk value, but still comparable to values reported for films grown at elevated temperature. Polycrystalline Heusler films combined with MgO barriers are incorporated into magnetic tunnel junctions and yield 37% magnetoresistance at room temperature.