1. J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejškova 3, 18223 Prague 8, Czech Republic
2. Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, 12116 Prague 2, Czech Republic
3. Strongly Correlated Systems “Lendület” Research Group, Wigner Research Centre for Physics, H-1525 Budapest, Hungary