A Ferrotoroidic Candidate with Well-Separated Spin Chains.

The search of novel quasi-1D materials is one of the important aspects in the field of material science. Toroidal moment, the order parameter of ferrotoroidic order, can be generated by a head-to-tail configuration of magnetic moment. It has been theoretically proposed that 1D dimerized and antiferromagnetic (AFM)-like spin chain hosts ferrotoroidicity and has the toroidal moment composed of only two antiparallel spins. Here, the authors report a ferrotoroidic candidate of Ba Cr S with such a theoretical model of spin chain. The structure consists of unique dimerized face-sharing CrS octahedral chains along the c axis. An AFM-like ordering at ≈10 K breaks both space- and time-reversal symmetries and the magnetic point group of mm'2'allows three ferroic orders in Ba Cr S : (anti)ferromagnetic, ferroelectric, and ferrotoroidic orders. Their investigation reveals that Ba Cr S is a rare ferrotoroid ic candidate with quasi 1D spin chain, which can be considered as a starting point for the further exploration of the physics and applications of ferrotoroidicity.