Visualizing uniaxial-strain-manipulation of antiferromagnetic domains in Fe_1+yTe using spin-polarized scanning tunneling microscope

The quest to understand correlated electronic systems has pushed the frontiers of experimental measurements towards development of new experimental techniques and methodologies. Here we use a novel home-built uniaxial-strain device integrated into our variable temperature scanning tunneling microscope (STM) that enables one to controllably manipulate in-plane uniaxial strain in the samples and probe their electronic response at the atomic scale. Using STM with spin-polarization techniques, we visualize antiferromagnetic (AFM) domains and their atomic structure in Fe_1+yTe, the parent compound of iron-based superconductors, and demonstrate how these domains respond to applied uniaxial-strain. We observe the bi-directional AFM domains in the unstrained sample, with an average domain size of ~ 50-150 nm, to transition into a single unidirectional domain under applied uniaxial-strain. Our findings open a new direction to utilize a valuable tuning parameter in STM as well as other spectroscopic techniques both for tuning the electronic properties as well as inducing symmetry breaking in quantum material systems.