Lattice/Spin/Charge Coupling in 5d Pyrochlore Cd₂Os₂O₇

Apr. 28 (Thu.) 3PM, #2501(E6-2. 2nd fl.)
Dr. Chang Hee Sohn, SEOUL NATIONAL UNIVERSITY

We investigated strong lattice/spin/charge coupling in 5d pyrochlore Cd₂Os₂O₇ by using optical spectroscopy. In the first part of the presentation, I’ll show strong effect of magnetic ordering on the charge dynamics of Cd₂Os₂O₇. In this compound, we observe that all-in/all-out antiferromagnetic ordering induces a Lifshitz-type metal-insulator transition that magnetic ordering gradually annihilates the Fermi surface. In the second part of the talk, I’ll present strong spin-lattice coupling in Cd₂Os₂O₇. We observed large renormalization of phonon frequencies below all-in/all-out antiferromagnetic ordering temperature, which can be understood in terms of modulation of Heisenberg exchange interaction and single ion anisotropy. Relevance to expected novel phenomena and future work will be discussed.

Contact: Eun Gook Moon, Physics Dept., (egmoon@kaist.ac.kr)