As a hallmark of electronic correlation, spin-charge interplay underlies many emergent phenomena in doped Mott insulators, such as high-temperature superconductivity, whereas the half-filled parent state is usually electronically frozen with an antiferromagnetic order that resists external control. We report on the observation of a positive magnetoresistance that probes the staggered susceptibility of a pseudospin-half square-lattice Mott insulator built as an artificial SrIrO3/SrTiO3 superlattice. Its size is particularly large in the high-temperature insulating paramagnetic phase near the Néel transition. This magnetoresistance originates from a collective charge response to the large longitudinal spin fluctuations under a linear coupling between the external magnetic field and the staggered magnetization enabled by strong spin-orbit interaction. Our results demonstrate a magnetic control of the binding energy of the fluctuating particle-hole pairs in the Slater-Mott crossover regime analogous to the Bardeen-Cooper-Schrieffer-to-Bose-Einstein condensation crossover of ultracold-superfluids.
Hao, Lin; Wang, Zhentao; Yang, Junyi; Meyers, D.; Sanchez, Joshua; Fabbris, Gilberto; Cho, Yongseong; Kim, Jong-Woo; Haskel, Daniel; Ryan, Philip J.; Barros, Kipton; Chu, Jiun-Haw; Dean, M.P.M.; Batista, Cristian D.; and Liu, Jian, "Anomalous magnetoresistance due to longitudinal spin fluctuations in a Jeff = 1/2 Mott semiconductor" (2019). Physics and Astronomy Publications and Other Works.