Readout of a antiferromagnetic spintronics systems by strong exchange coupling of Mn2Au and Permalloy

In antiferromagnetic spintronics, the read-out of the staggered magnetization or Neel vector is the key obstacle to harnessing the ultra-fast dynamics and stability of antiferromagnets for novel devices. Here, we demonstrate strong exchange coupling of Mn2Au, a unique metallic antiferromagnet that exhibits Neel spin-orbit torques, with thin ferromagnetic Permalloy layers. This allows us to benefit from the well-estabished read-out methods of ferromagnets, while the essential advantages of antiferromagnetic spintronics are retained. We show one-to-one imprinting of the antiferromagnetic on the ferromagnetic domain pattern. Conversely, alignment of the Permalloy magnetization reorients the Mn2Au Neel vector, an effect, which can be restricted to large magnetic fields by tuning the ferromagnetic layer thickness. To understand the origin of the strong coupling, we carry out high resolution electron microscopy imaging and we find that our growth yields an interface with a well-defined morphology that leads to the strong exchange coupling.Comment: 9 pages, 5 figure

Tuning the perpendicular magnetic anisotropy, spin Hall switching current density, and domain wall velocity by submonolayer insertion in Ta/CoFeB/MgO heterostructures

Bommanaboyena SP, Meinert M. Tuning the perpendicular magnetic anisotropy, spin Hall switching current density, and domain wall velocity by submonolayer insertion in Ta/CoFeB/MgO heterostructures. APPLIED PHYSICS LETTERS. 2017;111(4): 042407.By submonolayer insertion of Au, Pt, or Pd into Ta/CoFeB/MgO/Ta heterostructures, we tune the perpendicular magnetic anisotropy and the coercive field of the ferromagnetic layer. We demonstrate that this has a major influence on the spin Hall switching current density and its dependence on the external magnetic field. Despite a rather small effective spin Hall angle of theta(SH) approximate to -0.07, we obtain switching current densities as low as 2 x 10(10) A/m(2) with a 2 angstrom Au interlayer. We find that the Dzyaloshinskii-Moriya interaction parameter D is reduced with Au or Pd interlayers, and the perpendicular anisotropy field is reduced by an order of magnitude with the Pd interlayer. The dependence of the switching current density on the current pulse width is quantitatively explained with a domain wall nucleation and propagation model. Interface engineering is thus found to be a suitable route to tailor the current-induced magnetization switching properties of magnetic heterostructures. Published by AIP Publishing

RBS raw data for publication "High quality epitaxial Mn2Au (001) thin films grown by molecular beam epitaxy "

RBS raw data for publication "High quality epitaxial Mn2Au (001) thin films grown by molecular beam epitaxy " Simulation results using SINRA are included as well

Imaging of current induced Néel vector switching in antiferromagnetic Mn2 Au

The effects of current induced Néel spin-orbit torques on the antiferromagnetic domain structure of epitaxial Mn2Au thin films were investigated by x-ray magnetic linear dichroism–photoemission electron microscopy. We observed current induced switching of antiferromagnetic domains essentially corresponding to morphological features of the samples. Reversible as well as irreversible Néel vector reorientation was obtained in different parts of the samples and the switching of up to 30% of all domains in the field of view of 10 μm is demonstrated. Our direct microscopical observations are compared to and fully consistent with anisotropic magnetoresistance effects previously attributed to current induced Néel vector switching in Mn2Au

Néel Vector Induced Manipulation of Valence States in the Collinear Antiferromagnet Mn2_2 Au

The coupling of real and momentum space is utilized to tailor electronic properties of the collinear metallic antiferromagnet Mn2Au by aligning the real space Néel vector indicating the direction of the staggered magnetization. Pulsed magnetic fields of 60 T were used to orient the sublattice magnetizations of capped epitaxial Mn$_2$Au(001) thin films perpendicular to the applied field direction by a spin-flop transition. The electronic structure and its corresponding changes were investigated by angular-resolved photoemission spectroscopy with photon energies in the vacuum-ultraviolet, soft, and hard X-ray range. The results reveal an energetic rearrangement of conduction electrons propagating perpendicular to the Néel vector. They confirm previous predictions on the origin of the Néel spin–orbit torque and anisotropic magnetoresistance in Mn$_2$Au and reflect the combined antiferromagnetic and spin–orbit interaction in this compound leading to inversion symmetry breaking