High-field magnetization of the triangular-lattice antiferromagnet Gd1-xLaxPd2Al3

We have grown Gd1-xLaxPd2Al3 (x < 0.5) single crystals by the Czochralski p ulling method to investigate the magnetic dilution effect on the triangular -lattice antiferromagnet GdPd2Al3. The B-x and T-x phase diagrams were dete rmined by magnetic susceptibility and high-field magnetization measurements . The successive phase-transition temperatures T-N1 and T-N2 decrease linea rly with increasing x and vanish above about x = 0.8 and 0.55, respectively . When the field is applied along the c-axis, a 1/3 plateau of the full mag netic moments is clearly observed for x < 0.25 at 2 K and disappears for x > 0.4. We have discussed these experimental data by using the 2D triangular -lattice Heisenberg Hamiltonian with weak Ising-type anisotropy and the sit e percolation theory. (C) 2001 Elsevier Science B.V. All rights reserved.