Abstract: 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.

Abstract: An ultrathin, carbon-based memristor with a moiré 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 moiré 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.

Abstract: 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.

Abstract: An ultrathin, carbon-based memristor with a moiré 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 moiré 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.

Abstract: Disclosed is a method for producing and identifying a Weyl semimetal. Identification is enabled via a combination of the vacuum ultraviolet (low-photon energy) and soft X-ray (SX) angle resolved photoemission spectroscopy (ARPES). Production generally requires providing high purity raw materials, creating a mixture, heating the mixture in a container at a temperature sufficient for thermal decomposition of an impurity while preventing the possible reaction between the side walls of the container and the raw materials, depositing the resulting compound and a transfer agent onto the bottom surface of the ampule, differentially heating the ampule, and allowing a chemical vapor transport reaction to complete.

Abstract: 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.

Abstract: 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.

Abstract: Disclosed is a method for producing and identifying a Weyl semimetal. Identification is enabled via a combination of the vacuum ultraviolet (low-photon energy) and soft X-ray (SX) angle resolved photoemission spectroscopy (ARPES). Production generally requires providing high purity raw materials, creating a mixture, heating the mixture in a container at a temperature sufficient for thermal decomposition of an impurity while preventing the possible reaction between the side walls of the container and the raw materials, depositing the resulting compound and a transfer agent onto the bottom surface of the ampule, differentially heating the ampule, and allowing a chemical vapor transport reaction to complete.