ИСТИНА

We present results of the detailed electron spin resonance study nabokoite family compounds ACu7(TeO4)(SO4)5B (A=Na, K, Cs, Rb; B=Cl, Br) at the frequencies from 9 to 150 GHz and at the temperatures from 1.7 to 200 K. We have observed broad (line-width about 1 T) paramagnetic absorption in the paramagnetic phase which transforms to characteristic antiferromagnetic resonance at the ordering temperature. Absolute magnitude of this paramagnetic absorption corresponds to the 1/7 of all copper ions in the sample. This observation is a direct experimental evidence that “decorating” copper ions in interlayer positions orders at magnetic phase transition. I also allows to separate unambiguously contribution of SKL layers to static magnetic susceptibility. the later turns out to freeze out on cooling supporting predictions of gaped magnetic excitations in SKL antiferromagnet.