Condensed Matter Physics: from Hard Matter to Soft Matter
Ozan S. Sarıyer
Department of Chemistry, University of North Carolina at Chapel Hill
Contemporary condensed matter physics is broadly divided into two subfields, namely
hard and soft matter physics, based on the nature of materials of concern. From hard to soft
matter, the length scale of organization increases, while the energetic cost of destroying order
decreases. Yet the same practices of statistical mechanics apply to both subfields, since the
macroscopic materials, whether it is a piece of metal or rubber, constitute many degrees of
freedom in both cases. In this talk, I will present three distinct condensed matter phenomena
ranging from hard to soft matter, with larger emphasis on the latter. For each problem, a
separate set of tools of statistical mechanics is used. (i) In the hard matter limit, by using
renormalization-group theoretical approach, we obtained the spinless Falicov-Kimball model
global phase diagram , including four charge-ordered phases and exhibiting a very rich
topology. (ii) In the overlapping field from hard to soft matter, we investigated the dissipative
loss in the three-dimensional ±J Ising spin-glass  through scaling of the hysteresis area
by means of frustration-conserving hard-spin mean-field theory. We are planning to make
use of this approach in microscopic magnetic recording applications, especially in thin films.
(iii) As the main part of the talk, I will explain the microscopic model we developed for
elasticity of entangled polymer networks , a good example of soft matter systems. Our
approach can be used to model dry rubber, in which case we obtained excellent comparison
with experimental and simulation data, as well as to model swollen gels that can undergo
volume change upon deformation.
 O. S. Sarıyer, M. Hinczewski, and A. N. Berker, Phys. Rev. B 84 (20) 205120 (2011).
 O. S. Sarıyer, A. Kabak¸cıo˘glu, and A. N. Berker, Phys. Rev. E 86 (4) 041107 (2012).
 O. S. Sarıyer, S. Panyukov, and M. Rubinstein, APS March Meeting 2012 57 (1), Q45.4 (2012).