Shear modulus versus temperature, measured in magnetic fields between 0 and 9 Tesla.

1. Resonant Ultrasound Studies of spin-liquid Tb2Ti2O7 Veerle M. Keppens, The University of Tennessee Knoxville, DMR 0804719 The physical properties of geometrically frustrated magnets are known to display a wealth of exotic phenomena, because the lattice structure does not allow all interactions between the magnetic ions to be simultaneously satisfied. A recent example of a material where the frustration prevents magnetic ordering down to lowest measurable temperatures has been found in Tb2Ti2O7. We measured the temperature-dependence of the elastic moduli for Tb2Ti2O7 with and without an applied magnetic field. A striking elastic softening is observed in the absence of a magnetic field, and is arrested upon the application of a moderate magnetic field. Such dramatic softening is typically attributed to a structural phase transition, however, no transition has thus far been observed in Tb2Ti2O7. Theoretical modeling of our experimental data is currently under way. Shear modulus versus temperature, measured in magnetic fields between 0 and 9 Tesla.

2. Resonant Ultrasound Studies of spin-liquid Tb2Ti2O7 Veerle M. Keppens, The University of Tennessee Knoxville, DMR 0804719 Education and training Exposing students to real-world science and the cutting-edge technology with emphasis on the challenges and opportunities associated with Materials for the 21st Century, is of the utmost importance to motivate them to consider future careers that relate to technology. Not only is the training of graduate students and post-docs essential but motivating high school students is imperative to the advancement of science. In addition to the graduate students and post-docs involved in various aspects of this work, several high school students were sponsored through internships to spend one or more semesters in the Keppens lab and have learned different aspects of materials physics through hands on experience and interaction with the group. High school students from Farragut High School (TN) are learning aspects of materials physics and low-temperature technology through direct contact with the group and active involvement in the research.