Temperature-sensitive microgel particles present experimenters with a fantastic new variable for creation of novel phases and control of phase transformations. In particular, colloidal particle diameter and colloidal suspension particle volume fraction are readily tuned by small changes in temperature. I will describe recent experiments from my laboratory which exploit this phenomenon to learn new condensed matter physics. Recent experiments, for example, permit us to explore first steps of bulk melting in three-dimensional crystals ^[1], to elucidate melting mechanisms in liquid crystalline phases of matter ^[2], to characterize melting in two-dimensions wherein intermediate hexatic phases form ^[3], to create geometrically frustrated colloidal ‘anti-ferromagnets’ ^[4], and to study aging ^[5] and jamming ^[6] of glassy media.

• ^[1] A.M. Alsayed, M.F. Islam, J. Zhang, P.J. Collings, A.G. Yodh, Science 309, 1207-1210 (2005).
• ^[2] A.M. Alsayed, Z. Dogic, A. G. Yodh, Physical Review Letters 93, #057801 (2004).
• ^[3] Y. Han, N.Y. Ha, A.M. Alsayed, and A. G. Yodh, Phys. Rev. E 77, #041406 (2008).
• ^[4] Y. Han, Y. Shokef, A. M. Alsayed, P. Yunker, T. C. Lubensky, A. G. Yodh, Nature 456, 898-903 (2008).
• ^[5] P. Yunker, Z. Zhang, K.B. Aptowicz, A. G. Yodh, Physical Review Letters 103, #115701 (2009).
• ^[6] Z. Zhang, N. Xu, D.T.N. Chen, P. Yunker, A. Alsayed, K.B. Aptowicz, P. Habdas, A.J. Liu, S. Nagel, and A.G. Yodh, Nature 459, 230-233 (2009).

Monday, January 11, 2010, 12:00. ICFO’s Auditorium

Hosted by Prof. Turgut Durduran