ON THE CRYSTAL DISTORTION IN TETRAGONAL ND2CUO4

X-ray diffraction measurements have been performed on single crystal Nd2CuO4 in order to re-examine the structural distortion from the tetragonal symmetry which could trigger the successive magnetic phase transitions in Nd2CuO4. Previously reported reflections such as ( 1 2, 1 2, 3) which are forbidden in the I4/mmm space group were not detected. However, we did observe a peak at the ( 1 2, 1 2, 3) position when the incident beam was contaminated by excessive higher order components. Since there is no distortion from the I4/mmm symmetry there must be another mechanism for the successive magnetic phase transitions in Nd2CuO4. © 1990.