Massachusetts Institute of Technology

Suyang Xu

Nuh Gedik

Qiong Ma

Pablo Jarillo-Herrero

Liang Fu

Patrick A Lee

Ching-Kit Chan

Netanel Lindner

Zhiren Zheng

Gil Refael

Hiroki Isobe

Rectification is a process that converts electromagnetic fields into direct current (DC). Such a process underlies a wide range of technologies, including wireless communication, wireless charging, energy harvesting, and infrared detection. Existing rectifiers are mostly based on semiconductor diodes, with limited applicability to small voltages or high frequency inputs. Here, we present an alternative approach to current rectification that uses the electronic properties of quantum crystals without semiconductor junctions. We identify a new mechanism for rectification from skew scattering due to the chirality of itinerant electrons in time-reversal-invariant but inversion-breaking materials. Our calculations reveal large, tunable rectification effects in graphene multilayers and transition metal dichalcogenides. These effects can be used in high-frequency rectifiers by rational material design and quantum wavefunction engineering.

Current rectification based on noncentrosymmetric quantum materials

An ultrathin, carbon-based memristor with a moir&#xe9; superlattice potential shows prominent ferroelectric resistance switching. The memristor includes a bilayer material, such as Bernal-stacked bilayer graphene, encapsulated between two layers of a layered material, such as hexagonal boron nitride. At least one of the encapsulating layers is rotationally aligned with the bilayer to create the moir&#xe9; superlattice potential. The memristor exhibits ultrafast and robust resistance switching between multiple resistance states at high temperatures. The memristor, which may be volatile or nonvolatile, may be suitable for neuromorphic computing.

Carbon-based volatile and non-volatile memristors

The generation of photocurrent in an ideal two-dimensional Dirac spectrum is symmetry forbidden. In sharp contrast, a three-dimensional Weyl semimetal can generically support significant photocurrent due to the combination of inversion symmetry breaking and finite tilts of the Weyl spectrum. To realize this photocurrent, a noncentrosymmetric Weyl semimetal is coupled to a pair of electrodes and illuminated with circularly polarized light without any voltage applied to the Weyl semimetal. The wavelength of the incident light can range over tens of microns and can be adjusted by doping the Weyl semimetal to change its chemical potential.

Far-infrared detection using Weyl semimetals

Growing community of inventors

Cambridge, MA, United States of America

Suyang Xu