[1] Univ Gothenburg, Dept Phys, SE-41296 Gothenburg, Sweden
[2] Ruhr Univ Bochum, D-44801 Bochum, Germany
[3] Royal Inst Technol, SE-10691 Stockholm, Sweden
[4] Chungnam Natl Univ, Dept Phys, Taejon 305764, South Korea
[5] Univ Zagreb, Fac Sci, Dept Phys, Zagreb 1001, Croatia
[6] Heriot Watt Univ, Sch Engn & Phys Sci, Edinburgh EH14 4AS, Midlothian, Scotland
[7] Konkuk Univ, Sch Phys, Div Quantum Phases & Devices, Seoul 143701, South Korea