Magnetotransport Evidence For Irreversible Spin Reorientation In The Collinear Antiferromagnetic State Of Underdoped Nd2-Xcexcuo4

We make use of the strong spin-charge coupling in the electron-doped cuprate Nd2-xCexCuO4 to probe changes in its spin system via magnetotransport measurements. We present a detailed study of the out-of-plane magnetoresistance in underdoped single crystals of this compound, including the nonsuperconducting, 0.05 <= x <= 0.115, and superconducting, 0.12 <= x <= 0.13, compositions. Special focus is put on the dependence of the magnetoresistance on the field orientation in the plane of the CuO2 layers. In addition to the kink at the field-induced transition between the noncollinear and collinear antiferromagnetic configurations, a sharp irreversible feature is found in the angle-dependent magnetoresistance of all samples in the high-field regime, at field orientations around the Cu-O-Cu direction. The obtained behavior can be explained in terms of field-induced reorientation of Cu2+ spins within the collinear antiferromagnetic state. It is therefore considered an unambiguous indication of the long-range magnetic order.