低維量子物理國家重點實驗室傑出學者講座

Distinguished Speaker Series

Topic： Hidden Phases Revealed at the Surface of Layered Transition Metal Compounds Speaker： Professor Ward Plummer Louisiana State University Physicist & National Academy of Science Member Time： 14:00 pm, Thursday, May 26th, 2016 Location： Lecture Hall C302,New Science Building（理科樓C302） Abstract: Complexity in transition-metal compounds originates for the close and nonlinear coupling of spin, charge, orbital, and lattice degrees of freedom. Creating a surface disturbs the balance between these degrees of freedom, and in many cases results in phased Hidden in the bulk. Several examples will be presented to illustrate this phenomenon. 1) Dynamic antiphase spin domain walls have been proposed for the parent compound of the Fe based super-conductor BaFe2As2. The surface (√2x√2) R45o phase displays a coupled structural-magnetic antiphase domain walls with a reduced symmetry compared to the bulk. 2) The (1x2) surface phase Ca(Fe1-xCox)2 stabilizes Antiferromagnetic Ordering leading to the coexistence of superconductivity and antiferromagnetic ordering. 3) The final example is for Mndoped double-layer Ruthenate Sr3(Ru1-xMnx)2O7, where the surface phase diagram is almost opposite from the bulk due to surface induced tilt of the octahedral in the parent compound. The surface of Sr3(Ru0.84Mn0.16)2O7 is metallic while the bulk is insulating, because the surface tilt has been removed. Bio： Professor Plummer is a world-renowned scholar in surfaces, with a BA in Math and Physics from Lewis and Clark College, Portland, Oregon, and a Ph. D in Physics from Cornell University. He is a member of the National Academy of Science, a fellow of American Academy of Arts and Sciences (AAAS) and a recipient of Davission and Germer Prize of American Physical Society. He has authored ~400 papers, and has mentored for over 110 young scholars as graduate students or postdoctoral fellows.

低維量子物理國家重點實驗室 傑出學者講座

Distinguished Speaker Series

低維量子物理國家重點實驗室傑出學者講座