Electronic structure and topology across math xmlns="http://www.w3.org/1998/Math/MathML">msub>mi >T/mi>mi>c/mi>/msub>/math> in the magnetic Weyl semimetal math xmlns="http://www.w3.org/1998/Math/MathML">mrow>ms ub>mi>Co/mi>mn>3/mn>/msub>msub>mi>Sn/mi>mn> 2/mn>/msub>msub>mi mathvariant="normal">S /mi>mn>2/mn>/msub>/mrow>/math>

The new Eu 5 Al 3 Sb 6 phase has been successfully synthesized as a pure phase through Sn flux methods yielding large, high-quality crystals. This structure type features disordered Al clusters that appear in the form of dual tetrahedra. It crystallizes in the monoclinic C2/m space group exhibiting a rock-salt-like Eu−Sb framework with [Al 4 ] tetrahedra replacing some of the cationic Eu atoms (space group: C2/m, a = 8.151(1) Å, b = 14.181(2) Å, c = 8.145(1) Å, β = 109.577(2)°). The structure models the [Al 4 ] as dual tetrahedra with the Al atom sites 37.5% occupied along with Eu present on the central site at 8% occupancy and the remainder of the site being vacant. The presence of the [Al 4 ] cluster is further supported by HRTEM. Electronic structure calculations show that this material is a semimetal with observed band crossings close to the Fermi level. Strong Al−Sb antibonding interactions were found from COHP calculations close to the Fermi level and provide the rationale for the deficiency of the Al cluster. Mossbauer spectroscopy on Eu-151 and Sb-121 provides oxidation states of 2+ and 3− along with the local environment. Magnetic susceptibility measurements can be described well with a Curie−Weiss law where an effective moment of 7.80 μ B /mol Eu is obtained, consistent with Eu 2+ , and show canted antiferromagnetic behavior below 10 K. Temperature dependent resistivity shows a Kondo-like low-temperature upturn caused by enhanced scattering of the itinerant electrons with the 4f orbitals of Eu.

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 around 130K is due to an anomalous domain wall depinning upon cooling. 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 300Oe. This observation rules out the possibility that the anomaly stems from a second-order phase transition. Our results further suggest that changes in the shape of hysteresis loops from 5K to 170K are caused by an unusual temperature-dependent domain nucleation field that changes sign around 130K. The Kerr rotation images of the magnetic domains confirm that the domain walls depin between 120K and 140K.