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Seminar | Materials Science

Quantum States in Spin-Orbit-Coupled Materials: New Mechanism Approaching Quantum Spin Liquid and Colossal Magnetoresistance Materials

MSD Seminar

Abstract: The best place to discover new physics is in new materials, which is especially true in strongly spin-orbit-coupled transition metal materials where competing interactions with comparable strength are intertwined together. In this talk, I will briefly introduce two systems where quantum states defy all existing theoretical mechanisms and experimental precedents have been observed.

The first system consists of a series of highly lattice-sensitive trimer lattice iridates Ba3n+1Ir3nO9n+1 (n = 1, 2, ∞) that covers the extreme ends of a magnetic spectrum: the delicate quantum liquid driven by a new frustration mechanism (Ba4Ir­3O10, n = 1) on one end and an antiferromagnet with TN = 183 K (BaIrO3, n = ∞) on the other.

The second system, the ferrimagnetic insulator Mn3Si2Te6 showcases an unusual colossal magnetoresistance that occurs only when a magnetic polarization is avoided, which challenges all existing models and precedents. With evidence from neutron scattering and electric-current controlled measurements, we report that this quantum state is driven by chiral orbital currents (COC) flowing along the edges of the MnTe6 octahedra.