Magnetic properties and the crystal field problem for tetragonal HoBa(2)Cu(3)O(x).

Magnetic susceptibilities of the first and third orders as well as the magnetization of the singlet paramagnet HoBa(2)Cu(3)O(x) (x≈6.0) at low temperatures are studied experimentally using a SQUID magnetometer and compared with theoretical calculations. The magnetic behaviour of single-crystal HoBa(2)Cu(3)O(x) at low temperature is found not to follow the one calculated on the basis of the known crystal field parameters.