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Title: Magnetic and metal-insulator transitions in coupled spin-fermion systems

We use quantum Monte Carlo to determine the magnetic and transport properties of coupled square lattice spin and fermionic planes as a model for a metal-insulator interface. Specifically, layers of Ising spins with an intra-layer exchange constant J interact with the electronic spins of several adjoining metallic sheets via a coupling JH. When the chemical potential cuts across the band center, that is, at half-filling, the Neel temperature of antiferromagnetic (J > 0) Ising spins is enhanced by the coupling to the metal, while in the ferromagnetic case (J < 0) the metallic degrees of freedom reduce the ordering temperature. In the former case, a gap opens in the fermionic spectrum, driving insulating behavior, and the electron spins also order. This induced antiferromagnetism penetrates more weakly as the distance from the interface increases, and also exhibits a non-monotonic dependence on JH. For doped lattices an interesting charge disproportionation occurs where electrons move to the interface layer to maintain half-filling there.
Authors:
 [1] ;  [2] ;  [3]
  1. Pennsylvania State Univ., University Park, PA (United States). Dept of Physics; Univ. of California, Davis, CA (United States). Dept. of Physics
  2. Univ. Federal do Rio de Janeiro, Rio de Janeiro (Brazil)
  3. Univ. of California, Davis, CA (United States). Dept. of Physics
Publication Date:
OSTI Identifier:
1344112
Grant/Contract Number:
NA0001842
Type:
Accepted Manuscript
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 90; Journal Issue: 14; Journal ID: ISSN 1098-0121
Publisher:
American Physical Society (APS)
Research Org:
Univ. of California, Davis, CA (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY