TY - JOUR
T1 - Conducting states caused by a surface electric dipole in CrN(001) very thin films
AU - Botana, Antía S.
AU - Pardo, Víctor
AU - Baldomir, Daniel
AU - Blaha, Peter
PY - 2013/2/13
Y1 - 2013/2/13
N2 - We report a series of electronic-structure calculations for CrN films within the LDA + U method. In the bulk, it was found previously that with the onset of antiferromagnetic order, a gap opens and an insulating state appears. However, for thin films with increasing thickness (4-10 layers), we find that starting with a critical thickness of 10 (cubic symmetry) or 6 layers (orthorhombic) the gap closes and conducting states appear. The appearance of metallic states is connected with a structural relaxation at the surface, where Cr (N) atoms buckle inside (outside), forming an effective dipole moment. With CrN being a low-gap system, the electric dipoles at the surface caused by the Cr atoms displacing inwards shift the bands around the Fermi level significantly enough to drive those thin films metallic. The potential shift due to these surface dipoles is also visible in Cr and O core-level shifts.
AB - We report a series of electronic-structure calculations for CrN films within the LDA + U method. In the bulk, it was found previously that with the onset of antiferromagnetic order, a gap opens and an insulating state appears. However, for thin films with increasing thickness (4-10 layers), we find that starting with a critical thickness of 10 (cubic symmetry) or 6 layers (orthorhombic) the gap closes and conducting states appear. The appearance of metallic states is connected with a structural relaxation at the surface, where Cr (N) atoms buckle inside (outside), forming an effective dipole moment. With CrN being a low-gap system, the electric dipoles at the surface caused by the Cr atoms displacing inwards shift the bands around the Fermi level significantly enough to drive those thin films metallic. The potential shift due to these surface dipoles is also visible in Cr and O core-level shifts.
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U2 - 10.1103/PhysRevB.87.075114
DO - 10.1103/PhysRevB.87.075114
M3 - Article
AN - SCOPUS:84874535999
SN - 1098-0121
VL - 87
JO - Physical Review B - Condensed Matter and Materials Physics
JF - Physical Review B - Condensed Matter and Materials Physics
IS - 7
M1 - 075114
ER -