Topological phase transitions in strongly correlated systems: application to Co3Sn2S2
V. Yu. Irkhin, Yu. N. Skryabin
M. N. Mikheev Institute of Metal Physics, 620108 Ekaterinburg, Russia
The topological transition in the strongly correlated half-metallic
ferromagnetic compound Co3Sn2S2 from Weyl semimetal (including
chiral massless fermions) to a non-magnetic state is treated. This
transition goes with a change in topological invariant, and is
accompanied by a non-topological transition from saturated ferromagnetic
to paramagnetic state, the minority Fermi surface being transformed from
ghost (hidden) to real. A corresponding description is given in terms of
slave fermion representation for the effective narrow-band Hubbard model.
The system Co3Sn2S2 provides a bright example of coexistence of
non-trivial topology and strong low-dimensional ferromagnetism.
A comparison is performed with other compounds where frustrations
result in formation of a correlated paramagnetic state.