Mn$_2$VAl Heusler alloy thin films: Appearance of antiferromagnetism and an exchange bias in a layered structure with Fe

TL;DR

This study reports the growth of Mn$_2$VAl Heusler alloy thin films with controlled magnetic phases, revealing antiferromagnetism and exchange bias effects in layered structures with Fe, advancing understanding of magnetic properties in these materials.

Contribution

It demonstrates the epitaxial growth of Mn$_2$VAl films with controlled order and magnetic behavior, and observes exchange bias in a layered structure with Fe, which is a novel finding.

Findings

A2-type Mn$_2$VAl shows no spontaneous magnetization.

L2$_1$-type Mn$_2$VAl exhibits ferrimagnetism with 220 emu/cm$^3$ saturation magnetization.

Antiferromagnetic order observed via neutron diffraction at room temperature.

Abstract

Mn$_2$VAl Heusler alloy films were epitaxially grown on MgO(100) single crystal substrates by means of ultra-high-vacuum magnetron sputtering. A2 and L2$_1$ type Mn$_2$VAl order was controlled by the deposition temperatures. A2-type Mn$_2$VAl films showed no spontaneous magnetization and L2$_1$-type Mn$_2$VAl films showed ferrimagnetic behavior with a maximum saturation magnetization of 220 emu/cm$^3$ at room temperature. An antiferromagnetic reflection was observed with neutron diffraction at room temperature for an A2-type Mn$_2$VAl film deposited at 400$^\circ$C. A bilayer sample of the antiferromagnetic A2 Mn$_2$VAl and Fe showed an exchange bias of 120 Oe at 10 K.