Magnetic order in Nd2 –xCexCuO4 –δ

Abstract

The magnetic structures of Nd₂CuO₄ and Nd_1.97Ce_0.03CuO₄ have been solved at 1.6 K using powder neutron diffraction methods, and the magnetic cell (magnetic space group C′mm′m′) results from a √2 ×√2 rotation of the basal plane of the I4/mmm nuclear unit cell, with a Cu spin direction (½,½,0) parallel to the magnetic propagation vector k=(½,½,0); the Nd spins are also constrained by symmetry to lie in the same direction, while the Néel state is not very sensitive to electron doping in contrast to the extreme sensitivity to hole doping of the Néel state in La₂CuO₄, and a lower limit for the Cu ordering temperature is estimated to be 170 K.