[1] Japan Atom Energy Agcy, Condensed Matter Sci Div, Sayo, Hyogo 6795148, Japan
[2] Kyoto Sangyo Univ, Dept Phys, Fac Sci, Kyoto 6038555, Japan
[3] Japan Atom Energy Agcy, Adv Sci Res Ctr, Tokai, Ibaraki 3191195, Japan
[4] Osaka Univ, Grad Sch Sci, Toyonaka, Osaka 5600043, Japan