Chiral magnetic effect

The CME is a macroscopic quantum phenomenon present in systems with charged chiral fermions, such as the quark–gluon plasma, or Dirac and Weyl semimetals.

[1] The CME is a consequence of chiral anomaly in quantum field theory; unlike conventional superconductivity or superfluidity, it does not require a spontaneous symmetry breaking.

The experimental observation of CME in a Dirac semimetal, zirconium pentatelluride (ZrTe5), was reported in 2014 by a group from Brookhaven National Laboratory and Stony Brook University.

[2][3] The material showed a conductivity increase in the Lorentz force-free configuration of the parallel magnetic and electric fields.

In 2015, the STAR detector at Brookhaven's Relativistic Heavy Ion Collider[4] and ALICE at CERN[5] presented experimental evidence for the existence of CME in the quark–gluon plasma.

Graph of resistivity vs applied magnetic field strength in zirconium pentatelluride
Resistivity increases in a slab of zirconium pentatelluride with the strength of the applied magnetic field for all angles between the current and the field but the angle of 0° when they are parallel: in this configuration of the fields a chiral non-dissipative current appears.