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SUMMARY:Electron doping of samarium nickelate from first principles - Mich
 ele Kotiuga (Rutgers University)
DTSTART:20170822T131500Z
DTEND:20170822T141500Z
UID:TALK77271@talks.cam.ac.uk
CONTACT:Joseph Nelson
DESCRIPTION:Rare earth nickelates exhibit a rich temperature-composition p
 hase diagram involving charge\, orbital and magnetic ordering. Recent expe
 rimental work on samarium nickelate (SmNiO<sub>3</sub>) has demonstrated t
 hat SmNiO<sub>3</sub> can be doped with interstitial hydrogen in a reversi
 ble manner\, resulting in a large increase in resistivity and band gap [1]
 . To elucidate this behavior\, we used the first-principles density functi
 onal theory (DFT)&plus\;U method to study the effect of added electrons on
  the crystal and electronic structure of SmNiO<sub>3</sub>. Specifically\,
  we relaxed starting structures obtained by adding electron concentrations
  of 1/4\, 1/2\, 3/4\, and 1 per Ni\, compensated by a uniform positive bac
 kground\, to various low energy structures of pure SmNiO<sub>3</sub>\, whi
 ch include either an oxygen-octahedron shape distortion or a breathing dis
 tortion characteristic of disproportionation. We find that the added elect
 rons localize on the nickel sites resulting in a high spin Ni<sup>2&plus\;
 </sup> configuration\, leading to a large gap between the occupied and uno
 ccupied e<sub>g</sub> orbitals [2]. We also present results with the addit
 ion of interstitial ions at the same concentrations\, optimizing their pos
 itions as part of the relaxation process\, that show the same change in el
 ectronic structure and the band gap. \n\n[1] J. Shi\, Y. Zhou\, and S. Ram
 anathan\, Nature Communications *5*\, 4860 (2014).\n\n[2] F. Zuo\, P. Pand
 a\, M. Kotiuga\, J. Li\, M. G. Kang\, C. Mazzoli\, H. Zhou\, A. Barbour\, 
 S. Wilkins\, B. Narayanan\, M. Cherukara\, Z. Zhang\, S. K. R. S. Sankaran
 arayanan\, R. Comin\, K. M. Rabe\, K. Roy\, and S. Ramanathan\,  Nature Co
 mmunications *8*\, 240 (2017).
LOCATION:TCM Seminar Room\, Cavendish Laboratory
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