Category archives: Condensed matter

In 1882, Heinrich Hertz devoted himself to the study of electromagnetism, including the recent and still generally unappreciated work of Maxwell. Two years later he began his famous series of experiments with electromagnetic waves. During the course of this work, Hertz discovered the photoelectric effect, which has had a profound influence on modern physics. The […]

The interactions between moving charges and magnetic fields can be quite complicated; more if we consider the quantum effects. One example is the collection of Hall effects. Imagine that we have a conductor or a semiconductor through which a current is flowing. Then we apply a strong transverse magnetic field. As a result, we can […]

A collection of local magnetic moments arranged in a linear fashion that interact via some spin-spin coupling is generally known as a spin chain . This seemingly simple object is one of the most complex and rich physical systems that have been studied since the advent of quantum mechanics without a decline in interest ever […]

Any physical law in which the magnitude of a physical quantity is proportional to the reciprocal of the square of the distance (1/r 2) from the source of that property is known as an inverse-square law. Newton’s law of gravitation and Coulomb’s law are both examples. When Newton proposed his law of gravitation in his […]

A crystal lattice is formed by a repeated arrangement of atoms, ions, or molecules. Due to the enormous amount of atoms involved it is extremely unlikely that all these will be arranged in perfect order. Some atoms will not be exactly in the right place with the result that the lattice will contain defects. The […]

Originally developed in the context of condensed-matter physics and based on renormalization group ideas, tensor networks have been revived thanks to quantum information theory and the progress in understanding the role of entanglement in quantum many-body systems . Ikerbasque Research Professor Román Orús, one of the world foremost authorities in the field, has just published […]

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 have been created. This growth has been fueled mainly by […]

For centuries, metals were employed in optical applications only as mirrors and gratings. New vistas opened up in the late 1970s and early 1980s with the discovery of surface-enhanced Raman scattering (SERS) and the use of surface plasmon (collective electronic oscillations at the surface of metals) resonances for sensing. In a simplified picture and in […]

Elements with 4f or 5f electrons in unfilled electron bands and their componuds , which have ions carrying magnetic moments but do not magnetically order, or only do so at very low temperatures, are generally known as heavy-fermion or heavy electron systems because the scattering of the conduction electrons with the magnetic ions results in […]

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 […]