1. Manipulation of Structural and Physical Properties by Chemical Doping in Sr 3 (Ru 1-x Mn x ) 2 O 7 E. Ward Plummer, Louisiana State University & Agricultural and Mechanical College, DMR 1002622 The double-layered Sr 3 Ru 2 O 7 is a prototype strongly correlated system. With the partial replacement of Ru by Mn, it is found that both electronic and magnetic properties are modified. Fig. a shows that there are two boundary lines with T MIT representing the metal-insulator transition temperature and T M a characteristic temperature corresponding to the peak in magnetic susceptibility. Such dramatic property changes results from the local structure modification (octahedral rotation angle), even through the global structure retains the same symmetry. Neutron scattering measurements reveal an unexpected antiferromagnetic ordering with E-type spin configuration for x = 0.16 compound (in which the octahedron no longer rotates) ( see Fig. b). In order to understand how Mn doping leads to the change of electronic and magnetic properties, we performed scanning tunneling microscopy/spectroscopy study, which shows that (1) Mn dopant is randomly distributed, and (2) there is chirality of rotation as illustrated in the inset of Fig. c. The combined effort helps us elucidate the intrinsic properties this type of materials. (a) Bulk phase diagram of Sr 3 (Ru 1-x Mn x ) 2 O 7 as a function of the Mn doping x; (b) Spin configuration determined by neutron scattering measurements for x = 0.16 compound; (c) STM image on the surface of x = 0.16 compound, which shows chirality of rotation (red and yellow lines) centered at Mn site. Phys. Rev. B 84, 174411 (2011); ibid 85, 180410(R) (2012)

2. Cultivating the Future Scientists E. Ward Plummer, Louisiana State University & Agricultural and Mechanical College, DMR 1002622 LSU has continuously supported (three years) Donovan Myers (see picture at the bottom right) for undergraduate research, working in Jin’s laboratory. She has also mentored high- school students. Willis Wang (see picture at the bottom left) is one of these from Baton Rouge Magnet High School. As part of his school assignments, he conducted experimental research at LSU, focusing on growing NaCoO 2 single crystals, a compound promising for topological behavior on the surface and thermoelectric application in bulk. He graduated as a honor student and will be admitted to John Hopkins University in fall 2012. Our research group has developed unique expertise in the structural determination of solid surfaces by Low Energy Electron Diffraction (LEED), and we have used this capability as a training vehicle for undergraduates and to establish international collaborations. Hanna Manuel (see picture), an under- graduate in Math at LSU, won the outstanding poster award at the REU competition run by the Louisiana Alliance for Simulation-Guided Materials Applications (NSF funded). She is shown with her poster above. Also we have established a collaboration with the Federal University of Minas Gerais (UFMG) in Brazil on the development and utilization of LEED codes. Mr. D. D. dos Reis, a graduate student, has joined the LSU group.