MAGNETIC PHASE-DIAGRAM OF (NI1-XMGX)O SOLID-SOLUTIONS

A magnetic phase diagram of the (Ni(1-x)Mg(x))O solid solutions is drawn by the results of elastic magnetic neutron scattering and magnetic measurements. The ranges of homogeneous antiferromagnetism (0 less-than-or-equal-to x less-than-or-equal-to 0.37), tricritical behaviour or frustrated antiferromagnetism (0.37 < x less-than-or-equal-to 0.6), cluster spin glass (0.6 < x less-than-or-equal-to 0.75) and paramagnetic behaviour of the Ni2+ spin moments in the ground state (x greater-than-or-equal-to 0.8) are determined. It is shown that diamagnetic Mg2+ ions serve as a source of a random field inducing an extra diamagnetic moment of value 0.35-mu-B.