Magnetic ordering is intimately related to local atomic environment (nature and distances of neighboring atoms) and mechanical deformation can lead to a wide range of interesting phenomena. The coupling between mechanics and magnetism is particularly evident in ordered intermetallics that undergo plastic deformation, where dislocations may place atoms on new atomic sites, and therefore create new chemical environments and interatomic distances. In a recent study, plastic deformation has been demonstrated to strongly affect the magnetic behavior of the ferromagnetic Heusler alloy MnAu2Al [1]. This intermetallic, along with the entire family of Heuslers, crystallizes in the L21 structure with space group Fm3 ̅m. Grinding an annealed powder yields a complete suppression of the macroscopic magnetic moment while the broadening of x-ray diffraction lines evidence heavy plastic deformation [2].
In order to study the initial stages of plastic deformation in Heusler alloys, single-crystal micropillars were micromachined by focused ion beam milling, and tested mechanically by in situ micro-compression in combination with Laue microdiffraction at the BM32 beamline at ESRF in Grenoble (France). For this purpose, the FT-NMT04 nanoindenter (FemtoTools) was installed on the xyz-sample stage and Laue microdiffraction patterns were recorded during micro-compression giving access to the crystal orientation, deviatoric elastic strains, and defects. The distribution of the crystallographic orientations after micro-compression were accessed and compared to the initial state. The elongation of the orientation distribution on the inverse pole figure in the deformed state corresponds to lattice rotations from which specific slip systems are extracted. A broad shear band is visible in the orientation map of the deformed micropillar.
Complementary post-mortem dark field scanning transmission electron microscopy (STEM) and differential phase contrast STEM were performed on the same micropillars to correlate defects and local magnetic properties.

We acknowledge CNRS for funding within the joined collaboration between IM2NP and UCSB via the IRP CNRS DASEIN project.

References
[1] E. Levin et al., Phys. Rev. Mat. 2021, 5, 014408.
[2] B.E. Rhodes et al., Acta Mater. 2024, 119711