Phys. Rev. B 95, 041201(R) (2017)

When strong magnetic fields are applied to metals, the electron states can become quantized, causing many thermodynamic and transport properties to exhibit periodic oscillations — the cyclotron orbits of the electrons become quantized into Landau levels. Tianyu Liu and colleagues predict that it should be possible to see such quantum oscillations in topological semimetals without applying any magnetic fields.

Perhaps the best-known class of topological semimetal are Dirac semimetals, which can be considered as three-dimensional analogues of graphene, featuring electron bands with linear dispersion close to a Dirac point. Liu et al. use theoretical methods to show that in thin films of the Dirac semimetal cadmium arsenide, elastic strain acts as a chiral gauge potential, which means that applying strain is analogous to applying a magnetic field.

Using their proposed geometry, they predict that pseudomagnetic fields as large as 15 T could be realized — more than enough to quantize the electron states. As this effect relies on the linearly dispersing electron bands, it should work for other Dirac (as well as Weyl) semimetals, providing a new tool for mapping the Fermi surface of topological semimetals.