UC Irvine

The reduction of the Neél point TN of La2CuO4 by substitution of nonmagnetic Mg or Zn for Cu has been studied, with particular emphasis on keeping the oxygen content unaffected. In the low-concentration range (<10%), the rate of TN suppression is found to be the same as in other two-dimensional (2D) Heisenberg magnets such as K2CuF4 (S=1/2) and K2MnF4 (S=5/2). While this suppression rate is larger than for 2D Ising magnets, it is much smaller than the rapid TN reduction upon introduction of holes in La2CuO4 through oxygen excess or heterovalent substitution for La. Thus, no unusual quantum-magnetic dilution effects are observed in the S=1/2 La2CuO4 magnet. © 1991 The American Physical Society.