Piezomagnetism of superconducting iron chalcogenides

Experiments on the acoustoelectric transformation in superconducting compounds based on FeSe reveal the manifestation of piezomagnetism in them. It allows us to refer the family of superconducting chalcogenides to the systems with a hidden magnetic order and broken time-reversal symmetry. The anisotropy of the piezomagnetic response indicates that the crystal structure of these compounds belongs to the trigonal syngony, in the low-temperature phase.