As a 2D Dirac physics simulators, graphene harbors very efficiently mobile electrons and may find wide applications in electronics and other arena. Most experiments detect these electrons as if they were free and independent. Nevertheless, a simple estimation [1] suggests that, the ratio of U, the electrostatic energy to K, the kinetic energy, is about 2.2, which is very large. So, why has it been unseen yet ? The reason is ascribed to screening or say shielding effects. Such effects are very strong for nimble electrons, which is true for graphene. On the other hand, the shielding should not be on all scales. In fact, a simple Yukawa potential modeling this shielding suggests that, such effects becomes pronounced only for distances beyond a critical value. Inside this value, screening can be neglected and strong repulsions should reveal itself. Put in math, the shielding function depends on energy and momentum scales that are looked at. Now these authors [2] did nice experiments and confirmed this saying. They measured the shielding in graphite, which consists of loosely layered graphene.
Figure Caption: The effective, screened fine-structure constant,
, as defined in the text. (A) The magnitude of , plotted against momentum and energy. The Dirac dispersion 
is indicated by the white line. In the low momentum region, is larger above this line than below. (B) The phase of , in radians. [2][1] The estimation is done as
;[2] DOI: 10.1126/science.1190920
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