The quasi-two-dimensional layered oxide Sr₂IrO₄ has earned recognition for its novel spin-orbit Mott state and various analogies to cuprate physics. Neutron diffraction and x-ray scattering measurements show that it possesses a centrosymmetric magnetic ground state, consisting of a canted intralayer antiferromagnetic order with nonzero net magnetic moments in each layer stacked antiferromagnetically [1-4]. However, the onset of a second-harmonic generation (SHG) signal below the Néel temperature has suggested the presence of a distinct hidden magnetic order [5]. Using small in-plane magnetic fields, it is possible to manipulate the Néel order and help distinguish it from hidden order. In this talk, we will present magnetic-field-dependent SHG rotational anisotropy and microscopy studies that further elucidate the nature of this hidden state.

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