1. Verkin Institute for Low Temperature Physics and Engineering, Kharkov, Ukraine, 61103
2. W. Trzebiatowski Institute for Low Temperatures & Structure Research PAS, P.O. Box 1410, 50–950, Wroclaw, Poland
3. Kurdyumov Institute for Metal Physics, Kiev, Ukraine, 03142
4. I.M. Frantsevich Institute for Problems of Material Science, Chernivtsi, Ukraine, 58001