Local-Moment Ferromagnetism And Unusual Magnetic Domains In Fe1/4tas2 Crystals

Single crystals of Fe1/4TaS2 have been studied by using magneto-optical (MO) imaging and radio-frequency magnetic susceptibility, chi. Real-time MO images reveal unusual slow dynamics of dendritic domain formation, the details of which are strongly dependent upon magnetic and thermal history. Measurements of chi(T) show well-defined local-moment ferromagnetic transition at T approximate to 155 K as well as thermal hysteresis for 50 < T < 60 K. This temperature range corresponds to the domain-formation temperature as determined by MO. Together these observations provide strong evidence for local-moment ferromagnetism in Fe1/4TaS2 crystals with large temperature-dependent magnetic anisotropy.