Category Archives: Condensed matter

Terahertz (THz) radiation is all around us. For example, this page emits blackbody radiation mainly in the THz region (defined here from 0.3 THz to 30 THz). Because terahertz radiation begins at a wavelength of around one millimeter and proceeds […]

Symmetry is a unifying principle that governs all aspects of physics. The physical properties of crystalline solids are no different. But, as symmetry is progressively lowered through the 32 crystallographic point groups, novel transport effects emerge. Crystal symmetry dictates also […]

Topological insulators are materials with special universal properties, which are protected against perturbations. Such properties are theoretically described by topology, a branch of mathematics concerned with the properties of geometrical objects that are unchanged by continuous deformations. Topological insulators are […]

Nonlinear processes are attractive in microscopy and spectroscopy since they can be excited with light in the near‐infrared, which offers several advantages, from a deep tissue penetration capability or a reduced photodamage due to the lower photon energy, to a […]

One of the unique features of the chemistry of carbon (and, to some extent, silicon) is its ability to form long chains of atoms. Polymers are substances that have macromolecules composed of many repeating units (known as ‘mers’). Many naturally […]

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, […]

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 […]

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 […]

Any physical law in which the magnitude of a physical quantity is proportional to the reciprocal of the square of the distance (1/r2) from the source of that property is known as an inverse-square law. Newton’s law […]

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 […]