“…In such systems, not only the ordinary spin Kondo effect [15,16] but also the orbital Kondo effect due to the interplay between orbital and spin degrees of freedom occurs; the Kondo effect in multiple-dot systems [17,18,19,20,21,22,23,24,25,26], the singlet-triplet Kondo effect [27,28,29,30], and the SU(4) Kondo effect in single-dot systems [31,32,33,34,35].…”