News

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...

Wed, 10/11/2017

Together with Sergey Syzranov, I studied the conductivity of nodal line semimetals. These turn out to be qualitatively different from other semimetals, like Weyl or Dirac semimetals, because of an unusual screening that changes the nature of the Coulomb potential from 1/r to 1/r^2.  Most...