Computations in Science Seminars
Jan 2017
25
Wed 12:15
Peter B. Littlewood, Argonne National Laboratory, University of Chicago
e-mail:
Host: William Irvine ()
Organizer: Yuval Yifat ()
Metal-insulator transitions in jammed elastic media

The metal-insulator transition driven by strong electronic correlations – generically called the “Mott” transition – is usually described entirely by electronic Hamiltonians, with models designed to exhibit related emergent phenomena such as magnetism and superconductivity. In real solids, the electronic localization also couples to the crystal lattice, and it turns out that these elastic degrees of freedom insert important new entropic phenomena more familiar in soft matter physics.

The coupling to the lattice induces elastic strain fields, which have intrinsic long-range interactions that cannot be screened. When strain fields are produced as a secondary order parameter in phase transitions - as for example in ferroelectrics - this produces unexpected consequences for the dynamics of order parameter fluctuations, including the generation of a gap in what would otherwise have been expected to be Goldstone modes.

A very important class of transition metal oxides – the perovskites – can be thought of as an array of tethered octahedra where the Mott transition produces a shape-change in the unit cell. Coupling of the fundamental order parameter to octahedral rotations gives rise to large entropic effects that can shift the transition temperature by hundreds of degrees K , essentially by exploiting the physics of jammed solids. The insight might offer ways to make better refrigerators by enhancing electro-caloric and magneto-electric effects. I will also speculate on how this might be relevant for theories of the quantum critical point.

Feb 2017
1
Wed 12:15
Joshua A Frieman, Fermilab, University of Chicago
e-mail:
Host: Daniel Holz ()
Organizer: Kim Weirich ()
Feb 2017
8
Wed 12:15
Sungyon Lee, Texas A&M University
Host: Sid Nagel ()
Particle-induced viscous fingering

An inclusion of particles in a Newtonian liquid can fundamentally change the interfacial dynamics and even cause interfacial instabilities. For instance, viscous fingering can arise even in the absence of the destabilizing viscosity ratio between invading and defending phases, when particles are added to the viscous invading fluid inside a Hele-Shaw cell. Our experimental results demonstrate that the onset and characteristics of fingering are most directly affected by the particle volume fraction but also depend on the ratio of the particle to gap size. In particular, the formation and destabilization of a particle band are observed on the interface only when the particle diameter is comparable to the channel gap thickness. The physical mechanism behind the instability and a quantitative model will also be discussed.

Feb 2017
15
Wed 12:15
OPEN
Feb 2017
22
Wed 12:15
Pedro M Reis, Department of civil Engineering, MIT
e-mail:
Host: William Irvine ()
Mar 2017
1
Wed 12:15
Paul Wiegmann, University of Chicago
Host: William Irvine ()
Mar 2017
8
Wed 12:15
OPEN
Mar 2017
22
Wed 12:15
OPEN
Mar 2017
29
Wed 12:15
Ioana Marinescu, University of Chicago
e-mail:
Host: Daniel Holz ()
Apr 2017
5
Wed 12:15
Massimo Vergassola, University of California at San Diego (UCSD)
e-mail:
Host: William Irvine ()
Apr 2017
12
Wed 12:15
Jonathan Simon, University of Chicago
Apr 2017
19
Wed 12:15
OPEN
Apr 2017
26
Wed 12:15
Lenka Zdeborova, CNRS & CEA, Saclay, France
Host: Arvind Murugan ()
May 2017
3
Wed 12:15
OPEN
May 2017
10
Wed 12:15
OPEN
May 2017
17
Wed 12:15
OPEN
May 2017
24
Wed 12:15
OPEN
May 2017
31
Wed 12:15
OPEN