University of Connecticut

Events Calendar

Condensed Matter Physics Seminar

Thursday, August 2, 2018
2:00pm – 3:00pm

Storrs Campus
Gant West (Physics Building), P121

Connor A. Occhialini, Department of Physics, University of Connecticut

Negative thermal expansion near two structural quantum phase transitions

Recent experimental work has revealed that the unusually strong, isotropic structural negative thermal expansion in cubic perovskite ionic insulator ScF3 occurs in excited states above a ground state tuned very near a structural quantum phase transition, posing a question of fundamental interest as to whether this special circumstance is related to the anomalous behavior. To test this hypothesis, we report an elastic and inelastic x-ray scattering study of a second system Hg2I2 also tuned near a structural quantum phase transition while retaining stoichiometric composition and high crystallinity. We find similar behavior and significant negative thermal expansion below 100 K for dimensions along the body-centered-tetragonal c axis, bolstering the connection between negative thermal expansion and zero-temperature structural transitions. We identify the common traits between these systems and propose a set of materials design principles that can guide discovery of new materials exhibiting negative thermal expansion.

References:

1. Connor A. Occhialini, Sahan U. Handunkanda, Gian G. Guzman-Verri, Jason N. Hancock,

"Negative thermal expansion near two structural quantum phase transitions"

, Frontiers in Physical Chemistry and Chemical Physics (2018)

2. Connor A. Occhialini, Sahan U. Handunkanda, Ayman Said, Sudhir Trivedi, Gian G. Guzman-Verri, Jason N. Hancock, "Negative thermal expansion near two structural quantum phase transitions", Phys. Rev. Materials 1, 070603R (2017)

3. Connor A. Occhilaini, Sahan U. Handunkanda, Erin B. Curry, Jason N. Hancock, "Classical, quantum, and thermodynamics of a model exhibiting structural negative thermal expansion", Phys. Rev. B, 95, 094106 (2017)

4. Sahan U. Handunkanda, Connor A. Occhialini, Ayman H. Said, and Jason N. Hancock, "Two-dimensional nanoscale correlations in the strong negative thermal expansion material ScF3", Phys. Rev. B, 94, 214102 (2016)

Contact:

Prof. J. Hancock

Physics Department (primary)

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