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CATEGORIES:Electronic Structure Discussion Group
SUMMARY:Electron doping of samarium nickelate from first p
rinciples - Michele Kotiuga (Rutgers University)
DTSTART;TZID=Europe/London:20170822T141500
DTEND;TZID=Europe/London:20170822T151500
UID:TALK77271AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/77271
DESCRIPTION:Rare earth nickelates exhibit a rich temperature-c
omposition phase diagram involving charge\, orbita
l and magnetic ordering. Recent experimental work
on samarium nickelate (SmNiO3) has demo
nstrated that SmNiO3 can be doped with
interstitial hydrogen in a reversible manner\, res
ulting in a large increase in resistivity and band
gap [1]. To elucidate this behavior\, we used the
first-principles density functional theory (DFT)&
plus\;U method to study the effect of added electr
ons on the crystal and electronic structure of SmN
iO3. Specifically\, we relaxed starting
structures obtained by adding electron concentrat
ions of 1/4\, 1/2\, 3/4\, and 1 per Ni\, compensat
ed by a uniform positive background\, to various l
ow energy structures of pure SmNiO3\, w
hich include either an oxygen-octahedron shape dis
tortion or a breathing distortion characteristic o
f disproportionation. We find that the added elect
rons localize on the nickel sites resulting in a h
igh spin Ni2&plus\; configuration\, lea
ding to a large gap between the occupied and unocc
upied eg orbitals [2]. We also present
results with the addition of interstitial ions at
the same concentrations\, optimizing their positio
ns as part of the relaxation process\, that show t
he same change in electronic structure and the ban
d gap. \n\n[1] J. Shi\, Y. Zhou\, and S. Ramanatha
n\, Nature Communications *5*\, 4860 (2014).\n\n[2
] F. Zuo\, P. Panda\, M. Kotiuga\, J. Li\, M. G. K
ang\, C. Mazzoli\, H. Zhou\, A. Barbour\, S. Wilki
ns\, B. Narayanan\, M. Cherukara\, Z. Zhang\, S. K
. R. S. Sankaranarayanan\, R. Comin\, K. M. Rabe\,
K. Roy\, and S. Ramanathan\, Nature Communicatio
ns *8*\, 240 (2017).
LOCATION:TCM Seminar Room\, Cavendish Laboratory
CONTACT:Joseph Nelson
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