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Title: Exotic magnetism on the quasi-FCC lattices of the d3 double perovskites La2NaB'O6 (B' = Ru, Os)

We find evidence for long-range and short-range ($$\zeta$$~$=$$~70~\AA~at 4~K) incommensurate magnetic order on the quasi-face-centered-cubic (FCC) lattices of the monoclinic double perovskites La$$_2$NaRuO$_6$ and La$_2$NaOsO$_6$ respectively. Incommensurate magnetic order on the FCC lattice has not been predicted by mean field theory, but may arise via a delicate balance of inequivalent nearest neighbour and next nearest neighbour exchange interactions. In the Ru system with long-range order, inelastic neutron scattering also reveals a spin gap $$\Delta$$~$$\sim$$~2.75~meV. Magnetic anisotropy is generally minimized in the more familiar octahedrally-coordinated $3d^3$ systems, so the large gap observed for La$_2$NaRuO$_6$ may result from the significantly enhanced value of spin-orbit coupling in this $4d^3$ material.
 [1] ;  [2] ;  [3] ;  [4] ;  [3] ;  [2] ;  [2]
  1. ORNL
  2. ISIS Facility, Rutherford Appleton Laboratory (ISIS)
  3. University of South Carolina
  4. University of South Carolina, Columbia
Publication Date:
OSTI Identifier:
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Letters; Journal Volume: 112; Journal Issue: 11
Research Org:
Oak Ridge National Laboratory (ORNL); High Flux Isotope Reactor (HFIR)
Sponsoring Org:
SC USDOE - Office of Science (SC)
Country of Publication:
United States
4d and 5d magnetism; spin-orbit coupling