Role of substrate clamping on anisotropy and domain structure in the canted antiferromagnet <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>α</mml:mi><mml:mtext>−</mml:mtext><mml:msub><mml:mi>Fe</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math>

Antiferromagnets have recently been propelled to the forefront of spintronics by their high potential for revolutionizing memory technologies. For this, understanding formation and driving mechanisms domain structure is paramount. In this work, we investigate in a thin-film canted antiferromagnet $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$. We find that internal destressing fields domains do not follow crystal symmetry $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$, but fluctuate due substrate clamping. This leads an overall isotropic distribution N\'eel order with locally varying effective anisotropy antiferromagnetic thin films. Furthermore, show weak ferromagnetic nature $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$ qualitatively different dependence on magnetic field compared collinear antiferromagnets such as NiO. The insights gained from our work serve foundation further studies electrical optical manipulation