= 1/2 Mott semiconductor

While manipulation of antiferromagnetic (AFM) order arises to the forefront of spintronics, fluctuation of AFM order is a long-standing problem lying at the heart of correlated electron physics. By engaging with staggered magnetic field effect (STMF), the AFM fluctuation can be manifested as a set of emerging quantum phenomena [Nat. Phys. 14, 806 (2018)]. Here we will present the observation of a positive magnetoresistance that probes the staggered susceptibility of a Jeff = 1/2 Mott semiconductor, which is built as a strong spin-orbit coupled SrIrO3/SrTiO3 superlattice [Phys. Rev. Lett. 119, 027204 (2017)]. This magnetoresistance is particularly large in the insulating paramagnetic phase near the Néel transition. We illustrate its origin of a collective charge response to the large longitudinal spin fluctuations due to the STMF. This result demonstrates a magnetic control of the binding energy of the fluctuating particle-hole pairs in the Slater-Mott crossover regime [Nat. Commun. 10, 5301 (2019)].