Large intrinsic anomalous Hall effect in half-metallic ferromagnet Co3Sn2S2 with magnetic Weyl fermions (1712.09947v1)

Abstract: The origin of anomalous Hall effect (AHE) in magnetic materials is one of the most intriguing aspect in condensed matter physics and has been controversial for a long time. Recent studies indicate that the intrinsic AHE is closely related to the Berry curvature of occupied electronic states. In a magnetic Weyl semimetal with broken time-reversal symmetry, there are significant contributions on Berry curvature around Weyl nodes, which would lead to a large intrinsic AHE. Here, we report the large intrinsic AHE in the half-metallic ferromagnet Co3Sn2S2 single crystal. By systematically mapping out the electronic structure of Co3Sn2S2 theoretically and experimentally, the large intrinsic AHE should originate from the Weyl fermions near the Fermi energy. Furthermore, the intrinsic anomalous Hall conductivity depends linearly on the magnetization and this can be attributed to the sharp decrease of magnetization and the change of topological characteristics.

• The paper demonstrates that the large intrinsic anomalous Hall effect in Co3Sn2S2 originates from Berry curvature associated with magnetic Weyl nodes near the Fermi level.
• The paper employs first-principle calculations and ARPES measurements to confirm the consistency between theoretical predictions and experimental observations.
• The paper suggests that the interplay between magnetism and topology in this half-metallic ferromagnet can drive innovations in spintronics and quantum materials.

Overview of the Anomalous Hall Effect in Co$_3$Sn$_2$S$_2$ Single Crystal

This paper presents a detailed investigation into the origin and characterization of the large intrinsic Anomalous Hall Effect (AHE) in the half-metallic ferromagnet Co$_3$Sn$_2$S$_2$. The paper utilizes a combination of experimental techniques and theoretical modeling to elucidate the electronic structures and mechanisms underpinning the AHE in this material system, particularly focusing on the role of magnetic Weyl fermions.

Key Findings

The research confirms that the sizable AHE observed in Co$_3$Sn$_2$S$_2$ originates from its intrinsic electronic properties, closely associated with the presence of Weyl nodes located near the Fermi level. Systematic first-principle calculations and angle-resolved photoemission spectroscopy (ARPES) measurements demonstrate substantial agreement, supporting the alignment of theoretical predictions with experimental observations. Key findings include:

• Intrinsic Contributions: The Berry curvature of occupied electronic states in Co$_3$Sn$_2$S$_2$ is significantly influenced by magnetic Weyl nodes, leading to a strong intrinsic AHE. The intrinsic anomalous Hall conductivity (AHC) displays a near-linear dependence on the magnetization.
• Theoretical and Experimental Validation: First-principle calculations elucidate that the band structures are predominantly influenced by the 3d orbitals of Co atoms. The experimental ARPES data corroborate the presence of spindle-shaped Fermi surfaces and the role of Weyl fermions in the electronic structure.
• Magnetoresponsive Behavior: The anomalous Hall resistivity $(\rho_{xy})$ increases with decreasing temperature below the Curie temperature ($T_C$), while its saturation value decreases, capable of being described by either intrinsic or side-jump mechanisms.

Implications and Speculations

The confirmation of intrinsic AHE originating from Weyl fermions in Co$_3$Sn$_2$S$_2$ provides substantive insights into the interplay between topology and magnetism in ferromagnetic materials. Practically, this research underscores the potential for magnetic Weyl semimetals, particularly half-metallic ferromagnets, in electronics, notably in spintronic applications. The paper highlights the relationship between magnetic moment, Weyl nodes, and topological band structures, pivotal for designing materials with desired electronic and magnetic properties.

Theoretically, these findings underscore the impact of Berry curvature in topological materials and invite further exploration into manipulating electronic and magnetic properties via Weyl nodes by external perturbations like pressure, chemical doping, or magnetic fields. Future developments in material science and technology may focus on fabricating robust, tunable AHE materials for next-generation electronic components.

In conclusion, this paper significantly advances the understanding of AHE in Co$_3$Sn$_2$S$_2$, presenting comprehensive evidence of its intrinsic origins linked to magnetic Weyl fermions, while opening avenues for material innovation in quantum materials and spintronic applications.