https://doi.org/10.1140/epjb/e20020021
Orbital-selective Mott-insulator transition in Ca2-xSrxRuO4
1
Institute of Metal Physics,
Russian Academy of Sciences-Ural Division,
620219 Yekaterinburg GSP-170, Russia
2
Theoretische Physik , ETH-Hönggerberg
8093 Zürich, Switzerland
3
Yukawa Institute for Theoretical Physics, Kyoto University,
Kyoto 606-8502, Japan
Corresponding author: a sigrist@itp.phys.ethz.ch
Received:
27
July
2001
Published online: 15 January 2002
The electronic structures of the metallic and insulating phases of the
alloy series
Ca2-xSrxRuO4 () are calculated using LDA,
LDA+U and Dynamical Mean-Field Approximation methods. In the end
members the
groundstate respectively is an orbitally non-degenerate antiferromagnetic
insulator (x=0) and a good metal (x=2).
For x>0.5 the observed Curie-Weiss paramagnetic
metallic state which possesses a local moment with the unexpected spin
S=1/2, is
explained by the coexistence of localized and itinerant Ru-4d-orbitals.
For 0.2<x<0.5 we propose a state with partial orbital and
spin ordering. An effective model for the localized orbital and spin
degrees of freedom is discussed.
The metal-insulator transition at x=0.2 is
attributed to a switch in the orbital occupation associated with a
structural change of the crystal.
PACS: 75.30.-m – Intrinsic properties of magnetically ordered materials / 75.50.-y – Studies of specific magnetic materials
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2002