Dichroism Measurements on Mn3Si2Te6: a magnetically induced metal-insulator transition system

The interplay between magnetism and electronic structure is essential to describe the exotic magnetic quantum materials. A metal-insulator transition (MIT) in Mn3Si2Te6 gives us a unique spectroscopic opportunity to examine such an interplay. In this magnetic insulator, a strong magnetic exchange interaction in the Mn sub-lattice results in a ferrimagnetic ground state while the crystallographic symmetry makes a quantum degeneracy of two opposite orbital chiral bands. The spin easy axis is in-plane where the long-range order is induced by the exchange coupling between interlayer Mn sites. Upon a strong magnetic field along the c-axis, the degenerated bands are split and a chiral band crosses the chemical potential, then we can observe MIT. Hence, the polarized orbital chiral state is realized in the metal phase. The splitting is increased with the magnetic field, i.e. the c-axis spin moments, and the critical magnetic field is H//c ~ 4 T. In this beamtime proposal, we would like to measure X(M)LD and X(M)CD on Mn3Si2Te6. The experiment will provide us with the electronic origin of the magnetic exchange interaction and the spectroscopic demonstration of orbital chiral states.