Investigation of the magnetic structure of the magnetic Weyl heavy fermion,CeBi2, using single-crystal neutron diffraction

Strongly correlated systems, due to entanglement among different interactions, often exhibit exotic and fascinating physics such as heavy fermion behaviour, complex magnetic ordering, or unconventional superconductivity. Due to strong spin-orbit coupling in these materials, topological surface states (TSS) with an inverted band gap are found. The prominent band features of TSS predicted and experimentally realised include non-trivial linearly dispersive Dirac-cones and Weyl fermions. Recently CeBi2 was found to demonstrate heavy fermion Kondo-type behaviour. It undergoes a transition to a complex antiferromagnetic ground state at TN = 3 K, and on the application of a magnetic field, a ferromagnetic-like state appears. In addition, the magneto-resistance behaviour of CeBi2 suggests the existence of non-trivial TSS. However, a previous neutron powder diffraction study at 1.6 K on D20 at ILL of CeBi2 did not reveal any clear sign of magnetic Bragg peaks. So far, the magnetic properties of this Weyl semimetal have not been explored by single crystal neutron diffraction. Here we propose to resolve the antiferromagnetic structure of CeBi2 by single-crystal neutron diffraction experiments using the WISH diffractometer.