Many of the advances in the physics of correlated electron materials over the past several decades have been driven by developments in new materials. For a list that summarizes s everal of the areas of research which have emerged during this period and the materials that led to these advances, see the recent publication by Maple et al. "New correlated electron physics from new materials," which is given below. The broad class of materials that can be classified as being "correlated" i ncludes both oxides (e.g., cuprates and iron-pnictogen oxides) and intermetallics (e.g., heavy fermion f-electron compounds) where transition metal, rare earth, and actinide elements with partially filled d/f-electron shells promote unconventional behavior. Common characteristics include: unstable d/f-electron shells, reduced dimensionality, large unit cells, molecular units/clusters, oversize atomic cages with filler ions, light elements, and unusual metal/metalliod ratios. Competing interactions, based on coupled charge, spin, orbital, and lattice degrees of freedom, can be readily tuned by varying control parameters such as chemical composition (x), pressure (P), and magnetic field (H), providing a significant reservoir of correlated electron phenomena and complex phase diagrams in the hyperspace of x, T, P, H, etc.

 

In the study of these types of materials, the feedback loop between the synthesis of new compounds and characterization is critical to rapid progress. For this reason, I have focused on both of these aspects of experimental condensed matter research during my studies in Professor Maple's research group. In particular, for my dissertation, "Strongly correlated electron behavior in As-based and thin film Sb-based filled skutterudites," I investigated the synthesis and characterization of single crystal and thin film intermetallic specimens. More recently, I have been investigating several other pnictide (Pn) families, including the newly discovered Fe-Pn superconductors, LnFePnO (Ln = La, Ce, Pr, Nd, Sm, Gd and Pn = P, As).

 

I also regularly coordinate the education and community outreach programs that our group participates in throughout the year. I am most proud of our lab's involvement in the annual science days at the Del Mar Pines Elementary, Allen Elementary, and Toler elementary schools. At these events, children from 1^st - 6^th grade participate in a variety of experiments involving liquid nitrogen and high temperature superconductors. Our group also periodically participates in several community events. For instance, in 2008-2009, we spoke at the Physical Science Open House for the Sweetwater Union School district (2008) and the San Diego Science Festival (2009). Through these outreach events, some exceptional high school students were able to volunteer in our laboratory and obtain experience in crystal growth and characterization.

 

My educational activities also include advising undergraduate students through the Research Education for Undergraduates (REU) program and the Physics 199 course. In the REU program, outstanding students from throughout the country visit the University of California, San Diego for a ten week period to perform research experiments at a university laboratory. The Physics 199 course offers a similar opportunity to undergraduate students from UCSD.

 

During the past several years, I have also coordinated the relocation and reassembly of our entire lab from our old lab space in Mayer hall to our new lab space in the Mayer hall annex. This has been a highly involved process which has required extensive planning and engineering activities. Although the lab move is now completed, rebuild activities are ongoing. I am currently focusing on the reassembly and testing of two of our three dilution refrigerators.

 

R. E. Baumbach and M. B. Maple, “Filled skutterudites: magnetic and electrical properties,” Encyclopedia of Materials: Science and Technology accepted (2009).

 

R. E. Baumbach, J. J. Hamlin, L. Shu, N. Crisosto, D. A. Zocco, and M. B. Maple, “Superconductivity in LnFePO (Ln = La, Pr, and Nd) single crystals,” The New Journal of Physics 11, 025018 (2009).

 

M. B. Maple, R. E. Baumbach, J. J. Hamlin, D. A. Zocco, B. J. Taylor, N. P. Butch, J. R. Jeffries, S. T. Weir, B. C. Sales, D. Mandrus, M. A. McGuire, A. S. Sefat, R. Jin, Y. K. Vohra, J.-H. Chu, and I. R. Fisher, "New correlated electron physics from new materials," Physica B accepted (2009).

 

M. B. Maple, R. E. Baumbach, J. J. Hamlin, P.-C. Ho, L. Shu, D. E. MacLaughlin, Z. Henkie, R. Wawryk, T. Cichorek, and A. Pietraszko, "Strongly correlated electron phenomena in the filled skutterudites," Properties and Applications of Thermoelectric Materials. Nato Science for Peace and Security Series, Springer, V. Zlatic and A. C. Hewson eds. (2009).

 

M. M. Qazilbash, J. J. Hamlin, R. E. Baumbach, Lijun Zhang, D. N. Singh, M. B. Maple, and D. N. Basov, “Electronic correlations in the iron pnictides,” Nature Physics, published online 26 July (2009).

 

B. Nowak, O. Zogal, A. Pietraszko, R. E. Baumbach, M. B. Maple, and Z. Henkie, “Enhanced spin fluctuation in the As - based filled skutterudite LaFe₄As₁₂ : A ¹³⁹La NMR and ⁷⁵As NQR study," Physical Review B 79 214411 (2009).

 

R. Wawryk, Z. Henkie, A. Pietraszko, T. Cichorek, A. Jezierski, R. E. Baumbach, and M. B. Maple, "Possible metal-insulator transition in the filled skutterudite CeFe₄As₁₂," Journal of Physics: Conference Series accepted (2009).

 

R. E. Baumbach, P.-C. Ho, T. A. Sayles, M. B. Maple, R. Wawryk, T. Cichorek, T. Pietraszko, and Z. Henkie, “The filled skutterudite CeOs₄As₁₂: a hybridization gap semiconductor,” Proceedings of the National Academy of Sciences 105, 17307 (2008).

 

R. E. Baumbach, P.-C. Ho, T. A. Sayles, M. B. Maple, R. Wawryk, T. Cichorek, T. Pietraszko, and Z. Henkie. “Non-Fermi liquid behavior in the filled skutterudite compound CeRu₄As₁₂,” Journal of Physics: Condensed Matter 20, 075110 (2008).

 

R. E. Baumbach, W. M. Yuhasz, and M. B. Maple, “A metal insulator transition in YbFe₄Sb₁₂ granular thin films,” Thin Solid Films 516, 3378 (2008).

 

R. E. Baumbach, W. M. Yuhasz, and M. B. Maple, "Metal insulator transition in disordered YbFe₄Sb₁₂ thin films," Physica B 403, 800 (2008).

 

J. J Hamlin, R. E. Baumbach, D. A. Zocco, T. A. Sayles, and M. B. Maple, “Superconductivity in single crystals of LaFePO.” Journal of Physics: Condensed Matter 20, 365220 (2008).

 

B. J. Taylor, R. E. Baumbach, T. A. Sayles, and M. B. Maple, "Critical dynamic vortex fluctuations amidst a nascent peak effect in granular CeRu₂ thin films," Journal of Physics: Condensed Matter 20, 365220 (2008).

 

D. A. Zocco, J. J. Hamlin, R. E. Baumbach, M. B. Maple, M. A. McGuire, A. S. Sefat, B. C. Sales, R. Jin, D. Mandrus, J. R. Jeffries, S. T. Weir, and Y. K. Vohra, “Effect of pressure on the superconducting critical temperature of La[O_0.89F_0.11]FeAs and Ce[O_0.88F_0.12]FeAs," Physica C 468, 2229 (2008).

 

A. Slebarski, M. B. Maple, R. E. Baumbach, and T. A. Sayles, “Interplay between spin-glass-like and non-Fermi-liquid behavior in CeNi_1-xRh_xSn.” Physical Review B 77, 245133 (2008).

 

M. B. Maple, Z. Henkie, R. E. Baumbach, T. A. Sayles, N. P. Butch, P.-C. Ho, T. Yanagisawa, W. M. Yuhasz, R. Wawryk, T. Cichorek, and A. Pietraszko, "Correlated electron phenomena in Ce- and Pr-based filled skutterudite arsenides and antimonides," Journal of the Physical Society of Japan 77, Suppl. A (2008).

 

Z. Henkie, M. B. Maple, A. Pietraszko, R. Wawryk, T. Cichorek, R. E. Baumbach, W. M. Yuhasz, and P.-C. Ho, “Crystal growth and properties of the filled skutterudite arsenides.” Journal of the Physical Society of Japan 77, Suppl. A 128 (2008).

 

C. S. Turel, J. Y. T. Wei, W. M. Yuhasz, R. Baumbach, and M. B. Maple, "Andreev spectroscopy study of multigap pairing in PrOs₄Sb₁₂," Journal of the Physical Society of Japan 77, Suppl. A 21 (2008).

 

R. E. Baumbach, W. M. Yuhasz, and M. B. Maple, “Pulsed laser deposition of PrFe₄Sb₁₂ thin films.” Applied Physics A 84, 227 (2006).

 

D. E. MacLaughlin, M. S. Rose, J. E. Anderson, O. O. Bernal, R. H. Hefner, G. J. Nieuwenhuys, R. E. Baumbach, N. P. Butch, and M. B. Maple, “Effects of annealing on glassy dynamics and non-Fermi liquid behavior in UCu₄Pd.” Physica B 374, 177 (2006).

 

R. E. Baumbach, F. Bridges, L. Downward, D. Cao, P. Chesler, and B. Sales, “Off center phonon scattering sites Eu₈Ga₁₆Ge₃₀ and Sr₈Ga₁₆Ge₃₀.” Physical Review B 71, 024202 (2005).

 

F. Bridges, R. Baumbach, D. Cao, P. Chesler, M. Anderson, and B. Sales. “Probing phonon scattering sites in the thermoelectric clathrate Eu₈Ga₁₆Ge₃₀.” Radiation Effects and Defects in Solids 158, 343 (2003).