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Hunting for spin-charge responses of antiferromagnetic fluctuations in pseudo-spin-half square-lattice

Date: 2019-12-20
Time: 14:30
Venue: M253
Speaker: Dr. Lin Hao

University of Tennessee, USA


While manipulation of antiferromagnetic (AFM) order arises to the forefront of spintronics, it is a long-standing fundamental problem lying at the heart of correlated electron physics. For example, exploring AFM order is crucial for understanding emergent phenomena in Mott insulators, like high-Tc superconductivity and quantum criticality. In this talk, I will present a series of exciting findings in layered iridates, which is a newly established Mott system similar to cuprates but features a strong spin-orbit coupling. The pseudo-spin-half square-lattice systems were implemented as artificial layered iridates [(SrIrO3)1/(SrTiO3)m] to engage with  a staggered magnetic field effect due to the strong spin-orbit interaction. By tuning the SrTiO3 spacer, the AFM structure of the Mott insulating state can be engineered [1]. With m = 1, the staggered magnetic field effect leads to an intriguing positive anomalous magnetoresistance that probes the AFM susceptibility, because of the strong interplay between charge and longitudinal spin fluctuations [2]. Upon driving the AFM structure to the two-dimensional limit at m = 2, a hidden SU(2) symmetry is achieved, which was first proposed in cuprates but never experimentally realized. As a result, while the ordering temperature is significantly reduced by strong critical fluctuations, the staggered magnetic field effect allows an external field of only a thousandth of the superexchange interaction to greatly suppress the AFM fluctuations and enable a giant response of the AFM order [3].

[1] L. Hao et al., Phys. Rev. Lett. 119, 027204 (2017)

[2] L. Hao et al., Nat. Commun. 10, 5301 (2019)

[3] L. Hao et al., Nat. Phys. 14, 806 (2018)


Dr. Lin Hao received his PhD from University of Science and Technology of China in 2016, after which he moved to University of Tennessee as a postdoctoral research associate. He has a broad research interest, including quantum magnetism, spin-charge entanglement and multiferroicity in metal oxide heterostructures. One major focus is to integrate materials with distinct ground state through oxide-based hetero epitaxy to create artificial structure with crossing functionality, which is unachievable through traditional solid-state chemistry strategy.