A surface-tailored, purely electronic, mott metal-to-insulator transition.
Mott transitions, which are metal-insulator transitions (MITs) driven by electron-electron interactions, are usually accompanied in bulk by structural phase transitions. In the layered perovskite Ca(1.9)Sr(0.1)RuO4, such a first-order Mott MIT occurs in the bulk at a temperature of 154 kelvin on cooling. In contrast, at the surface, an unusual inherent Mott MIT is observed at 130 kelvin, also on cooling but without a simultaneous lattice distortion. The broken translational symmetry at the surface causes a compressional stress that results in a 150% increase in the buckling of the Ca/Sr-O surface plane as compared to the bulk. The Ca/Sr ions are pulled toward the bulk, which stabilizes a phase more amenable to a Mott insulator ground state than does the bulk structure and also energetically prohibits the structural transition that accompanies the bulk MIT.
Moore
R G
RG
Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996, USA.
Zhang
Jiandi
J
Nascimento
V B
VB
Jin
R
R
Guo
Jiandong
J
Wang
G T
GT
Fang
Z
Z
Mandrus
D
D
Plummer
E W
EW