29 research outputs found
Direct evidence of a zigzag spin chain structure in the honeycomb lattice: A neutron and x-ray diffraction investigation on single crystal
We have combined single crystal neutron and x-ray diffractions to investigate
the magnetic and crystal structures of the honeycomb lattice .
The system orders magnetically below K with Ir ions forming
zigzag spin chains within the layered honeycomb network with ordered moment of
/Ir site. Such a configuration sharply contrasts the
N{\'{e}}el or stripe states proposed in the Kitaev-Heisenberg model. The
structure refinement reveals that the Ir atoms form nearly ideal 2D honeycomb
lattice while the octahedra experience a trigonal distortion that
is critical to the ground state. The results of this study provide much-needed
experimental insights into the magnetic and crystal structure crucial to the
understanding of the exotic magnetic order and possible topological
characteristics in the 5-electron based honeycomb lattice.Comment: Revised version as that to appear in PR
Tuning electronic structures via epitaxial strain in Sr2IrO4 thin films
We have synthesized epitaxial Sr2IrO4 thin-films on various substrates and
studied their electronic structures as a function of lattice-strains. Under
tensile (compressive) strains, increased (decreased) Ir-O-Ir bond-angles are
expected to result in increased (decreased) electronic bandwidths. However, we
have observed that the two optical absorption peaks near 0.5 eV and 1.0 eV are
shifted to higher (lower) energies under tensile (compressive) strains,
indicating that the electronic-correlation energy is also affected by in-plane
lattice-strains. The effective tuning of electronic structures under
lattice-modification provides an important insight into the physics driven by
the coexisting strong spin-orbit coupling and electronic correlation.Comment: 9 pages, 5 figures, 1 tabl