Field-Modulated Anomalous Hall Conductivity and Planar Hall Effect in Co₃Sn₂S₂ Nanoflakes

Abstract

Time-reversal-symmetry-breaking Weyl semimetals (WSMs) have attracted great attention recently because of the interplay between intrinsic magnetism and topologically nontrivial electrons. Here, we present anomalous Hall and planar Hall effect studies on Co 3 Sn 2 S 2 nanoflakes, a magnetic WSM hosting stacked Kagome lattice. The reduced thickness modifies the magnetic properties of the nanoflake, resulting in a 15-time larger coercive field compared with the bulk, and correspondingly modifies the transport properties. A 22% enhancement of the intrinsic anomalous Hall conductivity (AHC), as compared to bulk material, was observed. A magnetic field-modulated AHC, which may be related to the changing Weyl point separation with magnetic field, was also found. Furthermore, we showed that the PHE in a hard magnetic WSM is a complex interplay between ferromagnetism, orbital magnetoresistance, and chiral anomaly. Our findings pave the way for a further understanding of exotic transport features in the burgeoning field of magnetic topological phases.

On the anomalous low-resistance state and exceptional Hall component in hard-magnetic Weyl nanoflakes

“…The longitudinal resistivity in the case when the applied field is antiparallel to the magnetization (antiparallel configuration) is even lower than that of the parallel case (Figure 2(b)), i.e., Δρ xx is negative. This behavior has been previously observed in our 180-nm-thick Co 3 Sn 2 S 2 single-crystalline nanoflakes [14] and can also be recognized in polycrystalline films (although the spin-related positive MR is mixed in) [13]. Evidently, the trend is a universal behavior in this low-dimensional Weyl system.…”

“…In addition to studies on possible QAHE and its practical applications, the unexplored properties of this magnetic Weyl low-dimensional system are important. Anomalous transport properties in Co 3 Sn 2 S 2 nanoflakes have been observed in our previous work [14]. However, these intriguing behaviors still need to be studied and analyzed in detail.…”

“…Anomalous transport properties in Co3Sn2S2 nanoflakes have been observed in our previous work [14]. However, these intriguing behaviors still need to be studied and analyzed in detail.…”

“…Epitaxial polycrystalline Co 3 Sn 2 S 2 films can be grown via molecular beam epitaxy and co-sputtering deposition methods [12,13]. Moreover, reports on Co 3 Sn 2 S 2 nanoflakes grown via the chemical vapor transport (CVT) method exist [14,15]. Out-of-plane ferromagnetic order and large anomalous Hall effects were observed.…”

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

“…Very recently, Co 3 Sn 2 S 2 was proposed as a material which hosts different types of topological fermions depending on the nature of the magnetic order [7][8][9][10][11]. The unit cell of Co 3 Sn 2 S 2 can be described by the R 3m space group, with the Co atoms, which reside on the 9d Wyckoff position, arranged on two-dimensional kagome lattices stacked along the crystal c axis [see Fig.…”