Whereas carrier mediated magnetic properties of GaMnAs are
relatively well controlled, the present situation for ZnMnO and
ZnCoO remains very unclear. RT FM was theoretically predicted
in heavily p-type ZnMnO [2] and n-type ZnCoO alloys [3,4] and
then observed experimentally. However, the origin of the observed
magnetic ordering remains not clear (see e.g. [5] and references
given there). It is more likely that RT FM of ZnCoO (also ZnMnO
and GaFeN [6]) is due to inclusions of foreign phases and metal
accumulations, rather than to ‘‘volume properties’’ of these two alloys
(see e.g. [5] and references given there). We observed that
samples with the uniform TM distribution show a paramagnetic
response. Such samples were grown by us at a low temperature
using Atomic Layer Deposition (ALD) [7,8]. They are used in the
present study.