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

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.