Robustness of low-field anomalous magnetism in kagome Co₃Sn₂S₂

Kagome Co₃Sn₂S₂ polycrystalline samples with different nominal mixtures of starting materials have been synthesized using solid-state-reaction method and characterized by X-ray diffraction (XRD) and electron probe microanalyzer (EPMA). AC susceptibility (χ'_ac) with fine tuning temperature and magnetic field dependence were measured. The H-T phase diagram of Co₃Sn₂S₂ derived from χ'_ac –T and dχ'_ac /dT–T with various magnetic fields is presented. The phase diagram including so-called A phase with 0 Oe ≦ H ≦ 600 Oe and 132 K ≦ T ≦ 173 K, which had been reported earlier. More interestingly, within 150 Oe ≦ H ≦ 300 Oe and 132 K ≦ T ≦ 160 K, a new feature so-called phase is found. These and phases are negligibly dependent on S-rich doping samples Co₃Sn₂S_2+x (0 ≦ x ≦ 0.34) indicating the robust of anomalous magnetism in low magnetic field. The possible origins for the novel observations in kagome Co₃Sn₂S₂ will be discussed.