Controlling Strain Gradients in Weyl Semimetals

Exposing Weyl semimetals to an external magnetic field leads to the quasiparticle chirality, which has attracted much attention over the past years. The magnetic field causes a shift in the node position and opens a new transport channel. The application of strong magnetic fields for future technological use of this phenomenon is technically impractical. An alternative path has been proposed theoretically¹. By using strain gradients in Weyl semi-metals it is possible to tune the position of the nodes in a spatially inhomogeneous manner, causing a similar effect as the application of a magnetic field, hence termed pseudo-magnetic field. In the Dirac semimetal Cd₃As₂ the application of the magnetic field leads to splitting into Weyl nodes with Fermi arcs only pointing along k_z, making this a good test candidate. We will show how the new concept of pseudo-magnetic fields is applied to Cd₃As₂. Using focused ion beam micro structuring we have been able to fabricate samples of Cd₃As₂ that can be deformed elastically by bending. Studying the coherent electron path composed of two Fermi arcs on opposing surfaces has allowed us to test the proposed pseudo-magnetic fields and to give an upper limit for its strength.
1: D. Pikulin and R. Ilan arXiv:1802.00512