Giant Hall Resistivity and Magnetoresistance in Cubic Chiral Antiferromagnet EuPtSi

EuPtSi crystallizes in the cubic chiral structure (P2(1)3, No. 198), which is the same as the non-centrosymmetric space group of MnSi with the skyrmion structure, and orders antiferromagnetically below a Neel temperature T-N = 4.05 K. The magnetization at 2K for the [111] direction indicates two metamagnetic transitions at the magnetic fields H-A1 = 9.2 kOe and H-A2 = 13.8 kOe and saturates above H-c = 26.6 kOe. The present magnetic phase between H-A1 and H-A2 is most likely closed in the (H, T) phase and is observed in a wide temperature range from 3.6 to 0.5 K. In this magnetic phase known as the A-phase, we found giant additional Hall resistivity Delta rho(H)(H) and magnetoresistance Delta rho(H), reaching Delta rho(H)(H) = 0.12 mu Omega.cm and Delta rho(H) = 1.4 mu Omega.cm, respectively. These findings are obtained for H parallel to [111] and [100], but not for H parallel to [110] and [112], revealing an anisotropic behavior in the new material EuPtSi.