The absence of mirror symmetry, or chirality, is behind striking natural phenomena found in systems as diverse as DNA and crystalline solids. A remarkable example occurs when chiral semimetals with topologically protected band degeneracies are illuminated with circularly polarized light. In circularly polarized light, the tip of the electric vector describes a circular helix about […]
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. Similar to other two-dimensional materials, TMD […]
When you first study electromagnetism, all the electromagnetic waves you find are plane ones, waves in which the electric and magnetic fields are both orthogonal to the direction of travel of the wave. But this is a mode – the field pattern of the propagating wave – that is somehow ideal, as it exists in […]
Acenes are the class of organic compounds made up of linearly fused benzene rings. The best known of acenes is the compound with three rings, anthracene. The larger representatives, like pentacene (the one with five rings) have potential interest in optoelectronic applications and are actively researched in chemistry and electrical engineering. Starphenes are 2D polyaromatic […]
Isolated atomic planes, two-dimensional (2D) materials, like graphene can be reassembled into designer heterostructures made layer by layer in a precisely chosen sequence. Such heterostructures are often referred to as ‘van der Waals’ and the simpler one is composed of just two layers (bilayer). In 2018, Pablo Jarillo-Herrero, an experimentalist at MIT, found that at […]
Molecules when excited from their ground state (S 0 ) to their lowest electronically excited states often change their electronic structure considerably, which impacts on a range of important molecular properties. For example, the reactivity of a molecule in its excited state often differs markedly from that in its S 0 state. Also, the charge […]
A cement is any of various substances used for bonding or setting to a hard material. A popular one, Portland cement, is a mixture of calcium silicates and aluminates made by heating limestone (CaCO3) with clay (that contains aluminosilicates) in a kiln. The product is then ground to a fine powder. When Portland cement is […]
Back in 1929, theoretical physicist Hermann Weyl predicted the existence of a new elementary particle with intriguing properties. Specifically, it would be massless (like a photon), have half-integer spin (like an electron) and exist in two mirror-image versions (like left- and right-handed gloves)—a property known as chirality. Imagine there exist a material in which an […]
Charge density wave (CDW) is a many-body state of matter in which both lattice and electron density are modulated by a new periodicity. CDW features discrete translational symmetry-breaking, and mostly occurs in low-dimensional materials. Although CDW behaviours have been found in many materials, the underlying mechanism and the driving forces of CDW transition are still […]
During the last decades, the electronics industry has been very successful in pushing forward the advancement of electronic building blocks, but the limit of silicon-based electronic devices especially in terms of miniaturization are almost reached. There are many ideas how to overcome this problem, for example, by adding functionality based on approaches originating from molecular […]