UMD Researchers Use a Simple Stretch to Create Powerful Pseudomagnetic Fields in Graphene

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While it seems simple enough to stretch a material in two directions—like tugging on the ends of a rubber band—the team discovered that the graphene sheet needed to not only be stretched, but that the sheet must also be shaped in a specific way. A simple rectangle or square of graphene, when stretched, would not create a pseudomagnetic field.

But, when the graphene was formed into a tapered shape like a trapezoid or pennant, pulling on the ends produces a strain that steadily increases along the length of the ribbon, and this constant strain gradient gives a uniform, and controllable, pseudomagnetic field. And the more strain applied to the material, the greater the magnetic force. The team’s model, which was verified across three computational models, predicts a tunable field magnitude from zero to 200 Tesla.

This type of controlled pseudomagnetic field creates the potential for new ways to study the motion of electrons in a controllable high magnetic field. Currently, there is no sustainable method for generating magnetic fields of this magnitude. The induced fields – if made more spatially uniform – could potentially enable new concepts of electronics, such as “valleytronics,” in which electrons separate between different valleys in the graphene band structure.

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