External magnetic fields can have a profound effect on the behavior of electrons in a material, but creating sufficiently large fields is tricky. In graphene, however, researchers have shown that straining the material leads to large “pseudomagnetic” fields that affect the electrons in a similar way. These fields tend to be non-uniform and concentrated in small areas. Using the theory of elasticity and computer simulations, Zhu et al. now show that it is possible to create the desirable uniform fields of tailored strengths by pulling on the ends of a graphene nanoribbon. The trick is in the tapered shape of the nanoribbon; varying the shape and the length of the ribbon produces fields of different strengths.
Phys. Rev. Lett. 115, 245501 (2015).