Patterning and Imaging AntiFerromagnets – PIAF

More than 80% of known magnetic substances have dominant antiferromagnetic interactions, often resulting in no or very small magnetization. This impedes their investigation, in particular when the magnetic properties must be mapped at the nanoscale. Indeed 50% of the magnetic materials are antiferromagnetic or weakly magnetic and insulating, therefore out of sight for existing microscopy techniques. This issue is becoming crucial since antiferromagnets (AFs) and non-collinear magnetic materials are emerging as a new paradigm for spintronics: (i) they are insensitive to spurious magnetic fields, suppressing the cross-talk between neighboring cells in antiferromagnetic devices, (ii) their intrinsic switching frequency is in the THz regime (versus 1-50 GHz for ferromagnets), (iii) they require low power to operate and sustain the propagation of pure spin waves without dissipation when insulating.

As it does not generate any stray field, the antiferromagnetic order is very discreet, which makes the processes of nucleation or growth of AF domains, as well as their responses to external stimuli at the microscopic scale, a virtually uncharted territory. This field is in its infancy and the scarcity of real space imaging techniques is a major bottleneck to understand the fundamental basis of the antiferromagnets’ manipulation, and to harness the unique features of antiferromagnets.

Within this framework, the PIAF project will have two main goals:

1- Develop the equivalent nanoscale control and imaging capabilities now routine for ferromagnets, for pure antiferromagnets and complex magnetic structures derived from antiferromagnets. This proposal aims first at imaging antiferromagnetic domains, domain walls and periodic spin orders with novel microscopy techniques such as single NV scanning magnetometry, sub-micron-resolved second harmonic generation and scanning magneto-optical microscopy. The project will develop an original and complementary set of table-top microscopy techniques, compatible with the “operando” manipulation of AFs.

2- Lay the basis for the manipulation of antiferromagnetic domains by electrical means and the design of artificial spin textures on-demand. The three “handles” at play for modifying the antiferromagnetic landscapes will be i) strain-induced actuation by piezoelectrics, ii) current-induced actuation by spin transfer torque and iii) electric-field-induced actuation with ferroelectric multiferroics. This will unlock the access to microscopic properties in the future of antiferromagnetic spintronics.