arXiv subjects

J. J. Heremans

Publications and source records attributed to J. J. Heremans.

9 recordsLinked to original sources

arXiv2021

Non-Fermi Liquids, Strange Metals and Quasi-metaparticles

We introduce the concept of quasi-metaparticles based on the theory of metaparticles, the zero modes of the metastring. We apply the concept of quasi-metaparticles to the problem of non-Fermi liquids and the properties of strange metals. In particular, we point out that the quasi-metaparticle Green's function interpolates between the canonical quasi-particle Green's function and the result found in the context of the SYK model, which presents an exactly solvable model without quasiparticles. The linear dependence of resistivity with temperature is reproduced in the SYK limit. Also, the Cooper mechanism is possible in the quasi-metaparticle case. Finally, the new parameter that characterizes quasi-metaparticles can be extracted from ARPES data. Thus, the quasi-metaparticle could be a useful new concept in the study of strange metals and high-temperature superconductivity.

cond-mat.str-el↗

arXiv2021

Exploring self-consistency of the equations of axion electrodynamics in Weyl semimetals

Recent works have provided evidence that an axial anomaly can arise in Weyl semimetals. If this is the case, then the electromagnetic response of Weyl semimetals should be governed by the equations of axion electrodynamics. These equations capture both the chiral magnetic and anomalous Hall effects in the limit of linear response, while at higher orders their solutions can provide detectable electromagnetic signatures of the anomaly. In this work, we consider three versions of axion electrodynamics that have been proposed in the Weyl semimetal literature. These versions differ in the form of the chiral magnetic term and in whether or not the axion is treated as a dynamical field. In each case, we look for solutions to these equations for simple sample geometries subject to applied external fields. We find that in the case of a linear chiral magnetic term generated by a non-dynamical axion, self-consistent solutions can generally be obtained. In this case, the magnetic field inside of the Weyl semimetal can be magnified significantly, providing a testable signature for experiments. Self-consistent solutions can also be obtained for dynamical axions, but only in cases where the chiral magnetic term vanishes identically. Finally, for a nonlinear form of the chiral magnetic term frequently considered in the literature, we find that there are no self-consistent solutions aside from a few special cases.

cond-mat.mes-hall↗

arXiv2021

Hydrodynamic and ballistic transport over large length scales in GaAs/AlGaAs

We study hydrodynamic and ballistic transport regimes through nonlocal resistance measurements and high-resolution kinetic simulations in a mesoscopic structure on a high-mobility two-dimensional electron system in a GaAs/AlGaAs heterostructure. We evince the existence of collective transport phenomena in both regimes and demonstrate that negative nonlocal resistances and current vortices are not exclusive to only the hydrodynamic regime. The combined experiments and simulations highlight the importance of device design, measurement schemes and one-to-one modeling of experimental devices to demarcate various transport regimes.

cond-mat.mes-hall↗

arXiv2016

Electromagnetic signatures of the chiral anomaly in Weyl semimetals

Weyl semimetals are predicted to realize the three-dimensional axial anomaly first discussed in particle physics. The anomaly leads to unusual transport phenomena such as the chiral magnetic effect in which an applied magnetic field induces a current parallel to the field. Here we investigate diagnostics of the axial anomaly based on the fundamental equations of axion electrodynamics. We find that materials with Weyl nodes of opposite chirality and finite energy separation immersed in a uniform magnetic field exhibit an anomaly-induced oscillatory magnetic field with a period set by the chemical potential difference of the nodes. In the case where a chemical potential imbalance is created by applying parallel electric and magnetic fields, we find a suppression of the magnetic field component parallel to the electric field inside the material for rectangular samples, suggesting that the chiral magnetic current opposes this imbalance. For cylindrical geometries, we instead find an enhancement of this magnetic field component along with an anomaly-induced azimuthal component. We propose experiments to detect such magnetic signatures of the axial anomaly.

cond-mat.mes-hall↗

arXiv2011

Gravitationally dressed Fermi Liquids, Quasiunparticles and High Tc Superconductivity

We clarify the new concept of gravitationally dressed Fermi liquids we have proposed to describe the normal state of high Tc superconductors. In this note we distinguish between weakly gravitationally dressed Fermi liquids which fall in the class of the canonical Fermi liquid theory (with quasiparticle excitations), and strongly gravitationally dressed Fermi liquids (with quasiunparticle excitations) which represent the high dimensional generalization of Luttinger liquids, with specific features. Such weakly or strongly gravitationally dressed Fermi liquids lead naturally to the previously proposed effective (weak or strong) gravitationally dressed Landau-Ginsburg description of either ordinary or high Tc superconductors.

hep-th↗

arXiv2010

Helical Aharonov-Casher edge states

It is shown that an Aharonov-Casher vector potential in a two-dimensional geometry can lead to helical edge states. The Aharonov-Casher vector potential is the electromagnetic dual of the magnetic vector potential, and leads to traveling states at the sample edge in analogy to the integer quantum Hall effect. The helical edge states are predicted to appear in a narrow channel geometry with parabolic or sufficiently symmetric confinement potential. The implications of the helical Aharonov-Casher edge states and experimental considerations in specific materials systems are discussed.

cond-mat.mes-hall↗

arXiv2010

Robustness of topologically protected surface states in layering of Bi2Te3 thin films

Bulk Bi2Te3 is known to be a topological insulator. We investigate surface states of Bi2Te3(111) thin films using density-functional theory including spin-orbit coupling. We construct a method to unambiguously identify surface states of thin film topological insulators. Applying this method for one to six quintuple layers of Bi2Te3, we find that the topological nature of the surface states remains robust with the film thickness and that the films of three or more quintuple layers have topologically non-trivial or protected surface states, in agreement with recent experiments.

cond-mat.mes-hall↗

arXiv2003

Spin-polarized reflection of electrons in a two-dimensional electron system

We present a method to create spin-polarized beams of ballistic electrons in a two-dimensional electron system in the presence of spin-orbit interaction. Scattering of a spin-unpolarized injected beam from a lithographic barrier leads to the creation of two fully spin-polarized side beams, in addition to an unpolarized specularly reflected beam. Experimental magnetotransport data on InSb/InAlSb heterostructures demonstrate the spin-polarized reflection in a mesoscopic geometry, and confirm our theoretical predictions.

cond-mat.mes-hall↗

arXiv2003

Hydrodynamic pumping of a quantum Fermi liquid in a semiconductor heterostructure

We describe both experimentally and theoretically a hydrodynamic pumping mechanism in a Fermi liquid, arising from electron-electron interaction. An electron beam sweeping past an aperture is observed to pump carriers from this aperture. Experimentally, the pumping effect induces a current in the lead connected to the aperture, or induces a voltage signal corresponding to carrier extraction from the lead. Different geometries display the effect, and this work discusses one experimental geometry in detail. Theoretically, the solution of the Boltzmann equation, including an electron-electron collision integral, shows that the potential induced by injected electrons becomes positive in the regions nearby the main stream of injected electrons. Thus, the repulsive Coulomb interaction leads to an attractive, pumping force in the Fermi liquid. The pumping mechanism here described is shown to be qualitatively different from the Bernoulli pumping effect in classical liquids.

cond-mat.mes-hall↗