Integration of antiferromagnetic Heusler compound Ru$_2$MnGe into spintronic devices

We report on the first integration of an antiferromagnetic Heusler compound acting as a pinning layer into magnetic tunneling junctions. The antiferromagnet Ru$_2$MnGe is used to pin the magnetization direction of a ferromagnetic Fe layer in MgO based thin film tunnelling magnetoresistance stacks. The samples were prepared using magnetron co-sputtering. We investigate the structural properties by X-ray diffraction and reflection, as well as atomic force and high-resolution transmission electron microscopy. We find an excellent crystal growth quality with low interface roughnesses of 1-3 A, which is crucial for the preparation of working tunnelling barriers. Using Fe as a ferromagnetic electrode material we prepared magnetic tunneling junctions and measured the magnetoresistance. We find a sizeable maximum magnetoresistance value of 135%, which is comparable to other common Fe based MTJ systems.