=1/2 Antiferromagnet by In Situ Anisotropic Strain

With the emergence of antiferromagnetic (AF) spintronics in recent years, Iridates have attracted great interests because of their exotic ground state with magneto transport properties, driven by the interaction between strong spin-orbit coupling (SOC) and electron correlations. As a prominent example, Sr₂IrO₄ is a quasi-two-dimensional Jeff =1/2 canted AF Mott insulator. Similar to S=1/2 moments, J_eff=1/2 moments have no single-ion anisotropy. They are however also very different in that the J_eff=1/2 moments can form significant inter-site quadrupoles that are highly sensitive to lattice distortion via the so-called ‘pseudo-JT’ effect. The strength and symmetry of the pseudospin-lattice coupling can be externally controlled by the application of in situ strain. In this work, we investigate the tuning of the metamagnetic transition of the AF structure in Sr₂IrO₄ by applying anisotropic strain of the B_2g symmetry. By measuring the magnetoresistance (MR) and angular dependence of MR at different magnitude of in situ anisotropic strain, we observed clear shifts of the critical field of the metamagnetic transition. X-ray resonance magnetic scattering (XRMS) is performed to reveal the underlying modulation of the AF structure.