Twisted bilayer graphene (TBG) has taken the spotlight in the condensed matter community since the discovery of correlated phases. Now, a team of researchers studies heterostructures of TBG and hexagonal boron nitride (hBN) using an atomistic tight-binding model together with semi-classical molecular dynamics to consider relaxation effects. Isolated atomic planes, two-dimensional (2D) materials, like graphene […]
The so-called van der Waals materials consist of two-dimensional layers bound by weak van der Waals forces. After the isolation of graphene, the field of two-dimensional van der Waals materials has experienced an explosive growth and new families of two-dimensional systems and block-layered bulk materials, such as tetradymite-like topological insulators – electronic materials that have […]
The scattering of conduction electrons in metals due to impurities with magnetic moments is known as the Kondo effect, after Jun Kondo, who analysed the phenomenon in 1964. This scattering increases the electrical resistance and has as a consequence that, in contrast to ordinary metals, the resistance reaches a minimum as the temperature is lowered […]
Diodes are everywhere these days as they are key elements for electronics, optics, and detection. A diode is an electronic device with two electrodes. In the obsolescent thermionic diode a heated cathode emits electrons, which flow across the intervening vacuum to the anode when a positive potential is applied to it. The device permits flow […]
For the past century, students of chemistry, materials science, and physics have been taught to model solid-state materials by considering their chemical composition, the number and location of their electrons, and lastly, the role of more complicated interactions. However, an international team of scientists has recently discovered that an additional ingredient must also be equally […]
Transition metal dichalcogenides (TMDs) are layered compounds which can be thinned down to the single-layer limit. While mechanical exfoliation generates atomically thin TMD flakes possessing an area of a few square microns, chemical and physical methods provide high-quality monolayers on large-area substrates, which are suitable for actual technological applications. TMDs are a class of van […]
Imagine a conductor or a semiconductor through which a current is flowing. Then we apply a strong transverse magnetic field. As a result, we can measure a potential difference at right angles to both the current and the field caused by the deflection of charge carriers by the field. This effect was described by Edwin […]
A quasicrystal is a solid structure in which there is long-range incommensurate translational order and a long-range orientational order with a point group. Translated, this simply means that a quasicrystal is ordered but not periodic and, still, it can fill space completely. In two dimensions, the fivefold symmetry of a pentagon is an example of […]
Some metals, alloys and transition-element salts exhibit a form of magnetism called antiferromagnetism. This occurs below a certain temperature, named after Louis Néel, when an ordered array of atomic magnetic moments spontaneously forms in which alternate moments have opposite directions. There is therefore no net resultant magnetic moment in the absence of an applied field […]
Twistology could be the study of unexpected changes or developments in stories or situations, from coups d’état to the fatherhood of Darth Vader. In condensed matter physics there is something similar, although the preferred name is twistronics (from twist and electronics). It is understood as the study of how the angle (the twist) between layers […]