Giant spin torque efficiency in single-crystalline antiferromagnet Mn2Au films

Antiferromagnetic (AFM) materials have attracted wide attention in spin-orbit torque (SOT)-based spintronic due to its abundant spin-dependent properties and unique advantage of immunity against external field perturbations. To act as the charge-to-spin conversion source in energy-saving spintronic devices, it is of great importance for the AFM material to possess a large spin torque efficiency (xi(DL)). In this work, using the spin torque ferromagnetic resonance (ST-FMR) technique and a Mn2Au/NiFe(Py) bilayer system, we systemically study the xi(DL) of AFM Mn2Au films with different crystal structures. Compared with polycrystalline Mn2Au with effective xi(DL) < 0.051, we show a much larger xi(DL) of similar to 0.333 in single-crystal Mn2Au, which arises from the large spin Hall conductivity instead of electrical resistivity. Moreover, with a further contribution of interfacial effects, the effective xi(DL) of single-crystalline Mn2Au/Py system increases to 0.731, which is more than two times larger than the value of similar to 0.22 reported for the Mn2Au/CoFeB system. By utilizing the large xi(DL) of Mn2Au in a perpendicularly magnetized MnGa/Mn2Au system, energy-efficient deterministic magnetization switching with a current density at similar to 10(6) A cm(-2) is achieved. Our results reveal a significant potential of Mn2Au as an efficient SOT source and shed light on its application in future AFM material-based SOT integration technology.

Automated summary

In this study, AFM Mn2Au films with different crystal structures were systematically investigated, and it was demonstrated that single-crystal Mn2Au possesses a significantly higher spin torque efficiency (xi(DL)) of approximately 0.333 compared to polycrystalline Mn2Au. Furthermore, the integration of interfacial effects in the single-crystal Mn2Au/Py system increased the effective xi(DL) to 0.731, more than two times larger than that reported for the Mn2Au/CoFeB system. This research highlights the potential of Mn2Au as an efficient SOT source and its application in future AFM material-based SOT integration technology.