Abstract
Colossal magnetoresistance is an extraordinary enhancement of the electric conductivity in the presence of a magnetic field, an important property of matter that has been studied for decades. It is conventionally associated with a magnetic-field-induced spin polarization, which drastically reduces spin scattering, thus electric resistance. Our earlier studies uncover an intriguing exception to this rule in that the electric resistivity in a magnetic insulator is reduced by up to 7 orders of magnitude only when a spin polarization is absent [1]. Here I report a newly identified quantum state in a honeycomb material where internal loop currents flowing along edges of crystal unit cells dictate electric conductivity, providing a key element driving the novel colossal magnetoresistance [2]. The unique nature and control of the exotic quantum state, along with implications of this discovery, will be presented and discussed after a brief review of conventional colossal magnetoresistance and loop currents in other materials.
References:
1. Colossal magnetoresistance via avoiding fully polarized magnetization in ferrimagnetic insulator Mn3Si2Te6, Yifei Ni, Hengdi Zhao, Yu Zhang, Bing Hu, Itamar Kimchi and Gang Cao, Letter of Phys. Rev. B 103, L161105 (2021); DOI:10.1103/PhysRevB.103.L161105
This event is organized by the HKU-UCAS Joint Institute of Theoretical and Computational Physics and HK Institute of Quantum Science & Technology