Kondo physics in a Ni impurity embedded in O-doped Au chains

S. DI NAPOLI, M. A. BARRAL, P. ROURA-BAS, ; L. O. MANUEL; A. M. LLOIS; A. A. ALIGIA

PHYSICAL REVIEW B

AMER PHYSICAL SOC

Lugar: New York; Año: 2015 vol. 92 p. 85120 - 85120

1098-0121

By means of ab initio calculations we study the effect of O doping of Au chains containing a nanocontact represented by a Ni atom as a magnetic impurity. In contrast to pure Au chains, we find that with a minimumO doping the 5d xz,yz states of Au are pushed up, crossing the Fermi level. We also find that for certain O configurations, the Ni atom has two holes in the degenerate 3d xz,yz orbitals, forming a spin S = 1 due toa large Hund interaction. The coupling between the 5d xz,yz Au bands and the 3d xz,yz of Ni states leads to a possible realization of a two-channel S = 1 Kondo effect. While this kind of Kondo effect is commonly found in bulk systems, it is rarely observed in low dimensions. The estimated Kondo scale of the system lies within the present achievable experimental resolution in transport measurements. Another possible scenario for certain  atomic configurations is that one of the holes resides in a 3d z 2 orbital, leading to a two-stage Kondo effect, thesecond one with SU(4) symmetry.