Anomalous Magnetoresistance due to Longitudinal Spin Fluctuations in a Jeff = 1/2 Mott Semiconductor

TL;DR

This study uncovers a new positive magnetoresistance in a Mott insulator, driven by longitudinal spin fluctuations and strong spin-orbit coupling, revealing magnetic control over charge responses near the Néel transition.

Contribution

It demonstrates a novel magnetoresistance mechanism linked to longitudinal spin fluctuations in a pseudospin-half Mott insulator with strong spin-orbit interaction.

Findings

Large positive magnetoresistance near the Néel transition

Magnetoresistance originates from collective charge response to spin fluctuations

Magnetic control of particle-hole pair binding energy in the crossover regime

Abstract

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 new 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 N\'eel transition. This novel 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 BCS-to-Bose-Einstein condensation crossover of ultracold-superfluids.