Magnetic and quadrupolar order in a one-dimensional ferromagnet with cubic crystal-field anisotropy

The zero-temperature phase diagram of a one-dimensional S = 2 Heisenberg ferromagnet with single-ion cubic anisotropy is studied numerically using the density-matrix renormalization-group method. Evidence is found that although the model does not involve quadrupolar couplings, there is a purely quadrupolar phase for large values of the anisotropy. The phase transition between the magnetic and quad-apolar phases is continuous and it seems to be characterized by Ising critical exponents. [S0163-1829(99)00621-9].