News

Wed, 10/02/2019

Mixed valence insulators (MVIs), such as SmB6, have drawn a lot of attention because they seem to exhibit many Fermi liquid-like properties even though they are electrically insulating. This strange combination of metallic and insulating behavior has led to suggestions of exotic, many-body...

Thu, 07/25/2019

In a recently-published paper in PRX, Adam Nahum, Jonathan Ruhman, and I show that the growth of entanglement in a quantum system with repeated measurements can be described via a mapping to classical percolation. The implication is that there is a critical measurement rate separating a "volume...

Fri, 04/12/2019

In a solid state material, temperature gradients give rise to electric currents due to a variation in the electron diffusion constant with temperature. The proportionality between the current and the temperature gradient is called the thermoelectric conductivity.

In a just-published paper...

Fri, 03/15/2019

In a usual electric conductor, running an electric current perpendicular to a magnetic field produces a transverse electric field -- this is the Hall effect.  In a recent study, however, Phuan Ong's group at Princeton explored a material (KHgSb) for which the Hall effect goes away completely...

Thu, 12/20/2018

Ultrathin topological insulators don't seem to behave the way they are supposed to. Instead of becoming insulators due to hybridization of the two closely-spaced Dirac surfaces, the system seems to remain metallic at all temperatures and for all positions of the chemical potential. There is also...

Fri, 08/24/2018

In a newly-published Rapid Communication, we have shown how the chiral anomaly in Weyl semimetals admits an analogue of "adiabatic demagnetization", which is a technique for low-temperature refrigeration. The idea is that abruptly turning on or off the chiral anomaly (by switching on/off...

Fri, 06/29/2018

In a new paper, Liang Fu and I have shown that one can achieve record-efficient thermoelectric performance using three-dimensional nodal semimetals (Dirac or Weyl semimetals) in a strong magnetic field.  The work is ...

Fri, 06/29/2018

In a recently-published series of papers, I explored the problem of the "tunneling anomaly" in bilayers of composite Fermions, together with Debanjan Chowdhury and Patrick Lee.  Our goal was to explain a recent series of experiments by Jim Eisenstein et. al. at Caltech, which observed a...

Tue, 02/13/2018

At a recent workshop at the Banff International Research Station, I gave a talk about the possibility of huge thermopower in nodal semimetals.  You can watch the seminar at the link below, or read the preprint at https://arxiv.org/abs/1706.06117

Thu, 01/04/2018

I have been invited to discuss my recent work on semimetals at a number of universities.  The title of the talk is "Semimetals Unlimited", and I discuss ways in which nodal semimetals can overcome the limits on electron mobility and thermopower that constrain semiconductors.

Caltech: Nov...