Condensed matter • Materials • Physics • Quantum physics • Theoretical physics
We all know what an insulator is, don’t we? An insulator is any substance that is a poor conductor of heat and electricity. Both properties ussually occur as a consequence of a lack of mobile electrons.If we want to dive a little deeper into the nature of insulators we make use of energy band theory […]
For a successful application in spintronics of any material, a key problem is to get a reliable control of the electronic spin within it. An ideal candidate for this purpose would be any material which is non-magnetic in the bulk but has a tunable ferromagnetic surface layer with a large splitting of the spin-up and […]
If a nucleus has a nonzero spin, it behaves as a small magnet. Therefore, in an external magnetic field, the nuclear magnetic moment vector precesses about the field direction but only certain otientations are allowed by quantum rules. Thus, for hydrogen (spin 1/2) there are two possible states in the presence of a field, each […]
The scattering of conduction electrons in metals owing 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 the consequence that, in contrast to ordinary metals, the resistance reaches a minimum as the temperature is lowered and […]
Many aromatic compounds can be made into organic semiconductors by doping them with a substance such as iodine, thereby producing mobile carriers of electric charge. This is analogous to the doping of silicon in an ordinary semiconductor. The benefits of using organic compounds are evident, namely, the resources are available everywhere, extremely cheap, and there […]
Since the discovery of graphene, a wide diversity of atomic-layer-thick, two-dimensional (2D) materials with varied properties have emerged. Of particular interest are those that exhibit semiconducting behavior, such as hexagonal boron nitride (hBN). hBN is isoelectronic to graphene and has also a honeycomb lattice formed by alternating nitrogen and boron atoms, but in contrast to […]
The way a particular reaction proceeds, described in terms of the steps involved, is called mechanism. The study of organic chemistry is, to a great extent, the study of reaction mechanisms and textbooks content both their description and their applications. But something has come to revolutionize the world of mechanisms: surface chemistry. On-surface synthesis is […]
So-called “valleytronics” is a new type of electronics that could lead to faster and more efficient computer logic systems and data storage chips in next-generation devices. Valley electrons are so named because they carry a valley degree of freedom, a pseudospin. This is a new way to harness electrons for information processing that’s in addition […]
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 […]
With the possible exception of Avogadro’s number, which was in reality defined and made popular by Stanislao Cannizzaro, many things in the sciences are usually named after the person who makes them popular. The Seebeck effect is an example. Originally discovered in 1794 by Alessandro Volta, it is named after Thomas Johann Seebeck, who in […]