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

Soh, Jian-Rui; Yi, ChangJiang; Zivkovic, Ivica; Qureshi, Navid; Stunault, Anne; Ouladdiaf, Bachir; Rodríguez-Velamazán, J. Alberto; Shi, YouGuo; Boothroyd, Andrew T.

doi:10.48550/arxiv.2110.00475

Cited by 3 publications

(3 citation statements)

References 30 publications

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“…From the µSR measurements, the ground ferromagnetic state with moment along c axis exists in Co 3 Sn 2 S 2 below T * C = 90 K, and a coexistence of the ferromagnetic order and an in-plane 120 • antiferromagnetic order was proposed at T > T * C [11] (see, however, Ref. [35]). The antiferromagnetic volume fraction grows with increasing temperature and dominates around 170 K, before it disappears at T C2 = 172 K. Above T C2 , the sample has the small volume fraction with the out-of-plane ferromagnetic order, the rest of the volume being occupied by the paramagnetic state up to T C1 = 177 K. The temperaturedependent magnetic fraction shows a rather sharp transition between the paramagnetic and magnetic states with the coexistence of their regions in the interval T C2 < T < T C1 .…”

Section: Discussionmentioning

confidence: 99%

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

Irkhin,

Skryabin

2021

Preprint

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The topological transition in the strongly correlated half-metallic ferromagnetic compound Co 3 Sn 2 S 2 from Weyl semimetal (including chiral massless fermions) to a non-magnetic state is treated. This transition goes with a change in topological invariant, and is accompanied by a non-topological transition from saturated ferromagnetic to paramagnetic state, the minority Fermi surface being transformed from ghost (hidden) to real. A corresponding description is given in terms of slave fermion representation for the effective narrow-band Hubbard model. The system Co 3 Sn 2 S 2 provides a bright example of coexistence of non-trivial topology and strong low-dimensional ferromagnetism. A comparison is performed with other compounds where frustrations result in formation of a correlated paramagnetic state.

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Section: Discussionmentioning

confidence: 99%

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

Irkhin,

Skryabin

2021

Preprint

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“…The primary structure is the ferromagnetic phase (FM) while the secondary structure is suggested as a possible in-plane antiferromagnetic phase (AFM) [14]. The neutron diffraction study by Soh et al, however, rules out the existence of an antiferromagnetic structure [15]. A recent half-polarized neutron diffraction investigation reveals there is a local symmetry broken below T C , where the kagome lattice starts to distort [16].…”

Section: Introductionmentioning

confidence: 99%

Magnetic domain walls depinning and the magnetization anomaly within the ferromagnetic phase of the Weyl semimetal Co3Sn2S2

Shen¹,

Zhu²,

Ullah³

et al. 2022

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We report bulk magnetization measurements and spatially resolved measurements of magnetic domains in Co3Sn2S2 single crystals. The results indicate that a previously reported magnetic anomaly at 130 K is due to domain wall pinning. Our measurements also reveal a hysteresis between field-cooled-cooling (FCC) and field-cooled-warming (FCW) magnetization curves acquired under a constant magnetic field below 300 Oe. The observation rules out the possibility that the anomaly stems from a second-order AFM-FM phase transition. Our results further suggest that changes in the shape of hysteresis loops from 5 K to 170 K is caused by an unusual temperature-dependent domain nucleation field that changes the sign at around 130 K. The Kerr rotation images of the magnetic domains obtained between 120 K and 140 K support the notion that a domain wall pinning effect exists near 130 K.

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“…The anomaly of the magnetic susceptibility, which may be relevant to the two-phase state, was also observed but at somewhat higher T A ∼ 130 K [12]. On the other hand, no evidence of the AFM component up to T C ∼ 177 K was observed in recent unpolarized neutron diffraction and spherical neutron polarimetry measurements [13].…”

Section: Introductionmentioning

confidence: 99%

Microscopic origins and stability of the ferromagnetism in Co$_3$Sn$_2$S$_2$

Solovyev,

Nikolaev,

Ushakov

et al. 2021

Preprint

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Based on the density functional theory, we examine the origin of ferromagnetism in the Weyl semimetal Co3Sn2S2 using different types of response theories. We argue that the magnetism of Co3Sn2S2 has a dual nature and bears certain aspects of both itineracy and localization. On the one hand, the magnetism is soft, where the local magnetic moments strongly depend on temperature and the angles formed by these moments at different Co sites of the kagome lattice, as expected for itinerant magnets. On the other hand, the picture of localized spins still remains adequate for the description of the local stability of the ferromagnetic (FM) order with respect to the transversal spin fluctuations. For the latter purposes, we employ two approaches, which provide quite different pictures for interatomic exchange interactions: the regular magnetic force theorem and a formally exact theory based on the calculation of the inverse response function. The exact theory predicts Co3Sn2S2 to be a three-dimensional ferromagnet with the strongest interaction operating between next-nearest neighbors in the adjacent kagome planes. The ligand states are found to play a very important role by additionally stabilizing the FM order. When the local moments decrease, the interplane interactions sharply decrease, first causing the FM order to become quasi-two-dimensional, and then making it unstable with respect to the spin-spiral order propagating perpendicular to the kagome plane. The latter instability is partly contributed by the states at the Fermi surface and may be relevant to the magnetic behavior of Co3Sn2S2 near the Curie temperature. Peculiarities of the half-metallic ferromagnetism in Co3Sn2S2 are also discussed. I.

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

Cited by 3 publications

References 30 publications

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

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

Magnetic domain walls depinning and the magnetization anomaly within the ferromagnetic phase of the Weyl semimetal Co3Sn2S2

Microscopic origins and stability of the ferromagnetism in Co$_3$Sn$_2$S$_2$

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