TY  - JOUR
AU  - Subedi, Alaska
AU  - Peil, Oleg E.
AU  - Georges, Antoine
TI  - Low-energy description of the metal-insulator transition in the rare-earth nickelates
JO  - Physical review / B
VL  - 91
IS  - 7
SN  - 1098-0121
CY  - College Park, Md.
PB  - APS
M1  - PUBDB-2016-03122
SP  - 075128
PY  - 2015
AB  - We  propose  a  simple  theoretical  description  of  the  metal-insulator  transition  of  rare-earth  nickelates.  Thetheory involves only two orbitals per nickel site, corresponding to the low-energy antibonding e<sub>g</sub> states. In themonoclinic insulating state, bond-length disproportionation splits the manifold of e<sub>g</sub> bands, corresponding to a modulation of the effective on-site energy. We show that, when subject to a local Coulomb repulsion U and Hund’s coupling J, the resulting bond-disproportionated state is a paramagnetic insulator for a wide range of interaction parameters. Furthermore, we find that when U − 3 J is small or negative, a spontaneous instability to bond disproportionation takes place for large enough J. This minimal theory emphasizes that a small or negativecharge-transfer energy, a large Hund’s coupling, and a strong coupling to bond disproportionation are the key factors underlying the transition. Experimental consequences of this theoretical picture are discussed.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000350315100001
DO  - DOI:10.1103/PhysRevB.91.075128
UR  - https://bib-pubdb1.desy.de/record/302079
ER  -