1. Laboratory “Magnetic Metamaterials,” Saratov State University, Saratov 410012, Russia
2. Institute of Electrical Engineering, Slovak Academy of Sciences, Dúbravská cesta 9, 841 04 Bratislava, Slovakia
3. Centre for Advanced Materials Application CEMEA, Slovak Academy of Sciences, Dubravska cesta 9, 845 11 Bratislava, Slovakia