The prediction of ultra-low magnetic damping in Co 2 MnZ Heusler half-metal thin-film magnets is explored in this study and the damping response is shown to be linked to the underlying electronic properties. By substituting the Z elements in high crystalline quality films (Co 2 MnZ with Z=Si, Ge, Sn, Al, Ga, Sb), electronic properties such as the minority spin band gap, Fermi energy position in the gap and spin polarization can be tuned and the consequence on magnetization dynamics analyzed. The experimental results allow us to directly explore the interplay of spin polarization, spin gap, Fermi energy position and the magnetic damping obtained in these films, together with ab initio calculation predictions. The ultra-low magnetic damping coefficients measured in the range 4.1 10 -4 -9 10 -4 for Co 2 MnSi, Ge, Sn, Sb are the lowest values obtained on a conductive layer and offers a clear experimental demonstration of theoretical predictions on Half-Metal Magnetic Heusler compounds and a pathway for future materials design.

Oxygen defects and their atomic arrangements play a significant role in the physical properties of many transition metal oxides. The exemplary perovskite SrCoO 3-δ ( P- SCO) is metallic and ferromagnetic. However, its daughter phase, the brownmillerite SrCoO 2.5 ( BM- SCO), is insulating and an antiferromagnet. Moreover, BM- SCO exhibits oxygen vacancy channels (OVCs) that in thin films can be oriented either horizontally ( H -SCO) or vertically ( V -SCO) to the film’s surface. To date, the orientation of these OVCs has been manipulated by control of the thin film deposition parameters or by using a substrate-induced strain. Here, we present a method to electrically control the OVC ordering in thin layers via ionic liquid gating (ILG). We show that H -SCO (antiferromagnetic insulator, AFI) can be converted to P -SCO (ferromagnetic metal, FM) and subsequently to V -SCO (AFI) by the insertion and subtraction of oxygen throughout thick films via ILG. Moreover, these processes are independent of substrate-induced strain which favors formation of H -SCO in the as-deposited film. The electric-field control of the OVC channels is a path toward the creation of oxitronic devices.