Degenerate magnetic ground state and metastable state on trihexagonal Co-sublattices in Co3Sn2(S,Se)2 single crystals

The magnetic structure of the topological semimetal Co$_3$Sn$_2$S$_2$

“…The field-cooled (FC) M (T ) and ρ yx (T ) curves both display an onset at T C = 177 K, below which M (T ) increases continuously to a maximum of 0.32µ B /Co at T = 2 K, and ρ yx attains a peak anomalous Hall effect near K. On warming in zero field (FC-ZFW), M (T ) and ρ yx (T ) both display a sharp anomaly at T A = 125 K, and M (T ) has a second sharp drop at 150 K. No sharp anomalies are observed for the ZFC data. These results are in good agreement with earlier studies in which similar measurement protocols were used [11,14,21,22,28]. Similar behavior is observed in the neutron polarization, Fig.…”

“…Finally, we note that the dramatic recovery of neutron polarization on warming above ∼120 K after cooling in a field [Fig. 2(c)], which is explained by a large reduction in FM domain size, correlates with the discontinuous change in magnetic, transport and optical data previously observed at T = T A [10,[24][25][26][27][28] [see also Fig. 2(a),(b)].…”

“…We see, therefore, that magnetic order is closely intertwined with the topology of the electronic bands in Co 3 Sn 2 S 2 , and so to understand its physical properties it is vital to know the true nature of the magnetic order. The second question concerns the origin of an anomaly observed in the vicinity of T A 125 K in magnetic, transport and optical measurements [10,[24][25][26][27][28]. In measurements of the Hall resistivity, Lachman et al found that the anomaly becomes extremely sharp and discontinuous when the sample is cooled in a field and measurements performed on warming in zero field (FC-ZFW) [14].…”

Topological phase transitions in strongly correlated systems: application to Co$_3$Sn$_2$S$_2$

“…Since magnetic frustration effects in the kagome lattice should play a role, the magnetic structure of Co 3 Sn 2 S 2 is to be discussed in more detail. According to [13], at finite temperatures this includes the out-of-plane ferromagnetism, in-plane antiferromagnetism, and hidden phases. A metastable magnetic phase exists in some interval T com < T < T C .…”

“…Recently, the layered kagome lattice compound Co 3 Sn 2 S 2 has been a subject of numerous experimental [1,2,3,4,5,6,7,8,9,10,11,12,13] and theoretical [14,15] investigations. In particular, giant topological anomalous Hall effect was observed in this system [3,6,8].…”