GdPt6Al3: A Canted Antiferromagnet with a Honeycomb Structure br

We have synthesized single crystals of GdPt6Al3 with a honeycomb network of Gd3+ ions with S = 7/2 Heisenberg spins. The measurements of magnetic susceptibility, electrical resistivity, Hall resistivity, magnetoresistance, specific heat, and magnetization are reported. The negative values of the paramagnetic Curie temperature -7.3 and -5.6 K for H II c and H perpendicular to c, respectively, indicate dominant antiferromagnetic (AFM) interaction. The specific-heat shows a second-order magnetic transition of S = 7/2 spins at Tm = 7.4 K. Application of magnetic field suppresses Tm, which is a characteristic of an AFM order. However, the magnetization for H perpendicular to c in the ordered state has a ferromagnetic component of 0.1 mu B/Gd. This small ferromagnetic component is likely caused by canting of local moments in the AFM state. No additional transitions within the AFM phase were observed in the magnetization, magnetoresistance, and Hall resistivity. We propose that the predominant AFM interaction among nearest-neighbor Gd moments in GdPt6Al3 hinders the formation of a skyrmion lattice.