  Antiferromagnetic thin films typically exhibit a multi-domain state, and
control of the antiferromagnetic N\'eel vector is challenging as
antiferromagnetic materials are robust to magnetic perturbations. By relying on
anisotropic in-plane strain engineering of epitaxial thin films of the
prototypical antiferromagnetic material LaFeO3, uniaxial N\'eel vector control
is demonstrated. Orthorhombic (011)- and (101)-oriented DyScO3, GdScO3 and
NdGaO3 substrates are used to engineer different anisotropic in-plane strain
states. The anisotropic in-plane strain stabilises structurally monodomain
monoclinic LaFeO3 thin films. The uniaxial N\'eel vector is found along the
tensile strained b axis, contrary to bulk LaFeO3 having the N\'eel vector along
the shorter a axis, and no magnetic domains are found. Hence, anisotropic
strain engineering is a viable tool for designing unique functional responses,
further enabling antiferromagnetic materials for mesoscopic device technology.
