All-electric measurement of the field-invariant magnetization of antiferromagnets

Antiferromagnetic materials combine magnetic properties in peculiar combination that is not found in their ferromagnetic counterparts. They are more robust against magnetic disturbances and show great promises in e.g. magnetoelectric applications [1,2]. Despite these fascinating fundamental properties, both the understanding of antiferromagnets and their commercial establishment have progressed slower than for ferromagnets. The tiny uncompensated magnetic moment of the locally uncompensated antiferromagnetic lattice is often the linking element to intrinsic processes that experimenters can exploit or devices can rely on.
One of the most sensitive techniques for thin film magnetometry, the anomalous Hall effect (AHE) [3], is routinely employed to study magnetization eversal in ferromagnets [4] by monitoring the magnetization-proportional anomalous Hall resistance.
However, this typically suffers from a sizable parasitic signal offset due to imperfect device geometry. But, the offset also contains real AHE signals generated by field-invariant magnetization components which are inaccessible in conventional Hall measurements.
We demonstrate, that AHE magnetometry using the spinning-current technique can measure such field-invariant magnetization on an absolute scale by dynamically compensating the parasitic resistance contribution (Fig.) [5]. Thus, we acquire previously unattainable figures about antiferromagnetic materials and refine existing measurements due to the great precision and time-efficiency of AHE magnetometry.
We establish that this technique is suitable to probe a wide range of materials by applying it to polycrystalline IrMn thin films as well insulating Cr 2 O 3 films. Moreover, our all-electric measurements also prove that it is feasible to entirely omit ferromagnets in antiferromagnet-based applications. Doing so paves the way to all-antiferromagnet spintronics with improved performance or improved reliability [6].

[1] X. He, Y. Wang, N. Wu, A. N. Caruso, E. Vescovo, K. D. Belashchenko, P. A. Dowben, and C. Binek, Nature Materials 9, 579 (2010).
[2] J. Heron, J. Bosse, Q. He, Y. Gao, M. Trassin, L. Ye, J. Clarkson, C. Wang, J. Liu, S. Salahuddin, and others, Nature 516, 370 (2014).
[3] N. Nagaosa, J. Sinova, S. Onoda, A. MacDonald, and N. Ong, Rev. Mod. Phys. 82, 1539 (2010).
[4] D. Bhowmik, L. You, and S. Salahuddin, Nature Nanotechnology 9, 59 (2014).
[5] T. Kosub, M. Kopte, F. Radu, O. G. Schmidt, and D. Makarov, Phys. Rev. Lett. 1, 1 (2015).
[6] T. Kosub, O. G. Schmidt, and M. Denys, Patent Applied For (n.d.).