Using Polarization Of Light To Put A Twist On Electrons

Using a particular kind of light beam (polarization of light) to stimulate certain exotic materials has led a team of scientists to discover that an identically asymmetrical pattern can be produced and measured at will in these materials.

In this instance, the “handedness” phenomenon—known as chirality—occurs in the abundance of electrons within the substance rather than in the molecules’ structure. The scientists discovered that this asymmetric patterning could be created by illuminating an uncommon substance known as TiSe2, or titanium diselenide, with circularly polarized mid-infrared light.

Titanium diselenide does not exhibit chirality at room temperature. However, as its temperature drops, it hits a point where the ratio of right-handed to left-handed electronic configurations is upset, and one type starts to predominate. Shining circularly polarized mid-infrared light at the material can enhance and control this effect. The chirality of the resulting electron distribution patterning depends on the light’s handedness (whether the polarization of the light rotates clockwise or counterclockwise).

According to researchers, it’s an unusual material that we need help understanding. Like a stack of papers, the substance organically organizes itself into “loosely stacked two-dimensional layers on top of each other.” Within those layers, the arrangement of electrons creates a “charge density wave function,” a series of alternating bands of more- and less-densely-packed electron regions.

Read more

Related Content: A Kaleidoscopic Approach To Polarization