Research articlesSpin-flop quasi-first order phase transition and putative tricritical point in Gd3Co

•Competing antiferro and ferromagnetic interactions in Gd3Co.•Magnetic field-induced antiferromagnetic to ferromagnetic transformation via a spin-flop over region.•Field-induced putative tricritical point where quasi-first order transition ends and second order phase transition sets in.•Magnetic field-temperature phase diagram showing possible field-induced magnetic phase transitions in Gd3Co.

Magnetic nature of Gd3Co is investigated using detailed measurements of temperature and field dependent magnetization. The antiferromagnetic phase is field-instable due to prevailing ferromagnetic exchange correlations above Néel temperature TN∼130K. Below TN, with gradually increasing magnetic fields, the compound undergoes a quasi-first order phase transition from AFM to spin-flop over region and eventually acquires ferromagnetic phase in higher fields. Further the point at which the quasi-first order transition ends and second order transition sets in is the tricritical point, TTCP∼125.6K, HTCP∼4.4kOe.