Spin-orbit effects in Na$_4$Ir$_3$O$_8$, a hyper-kagomé lattice antiferromagnet
| dc.creator | Chen, Gang | |
| dc.creator | Balents, Leon | |
| dc.date | 2008-06-10 | |
| dc.date | 2008-06-12 | |
| dc.date.accessioned | 2026-07-07T10:06:57Z | |
| dc.date.available | 2026-07-07T10:06:57Z | |
| dc.description | We consider spin-orbit coupling effects in Na$_4$Ir$_3$O$_8$, a material in which Ir$^{4+}$ spins form an hyper-kagomé lattice, a three-dimensional network of corner-sharing triangles. We argue that both low temperature thermodynamic measurements and the impurity susceptibility induced by dilute substitution of Ti for Ir are suggestive of significant spin-orbit effects. Because of uncertainties in the crystal-field parameters, we consider two limits in which the spin-orbit coupling is either weak or strong compared to the non-cubic atomic splittings. A semi-microscopic calculation of the exchange Hamiltonian confirms that indeed large antisymmetric Dzyaloshinskii-Moriya (DM) and/or symmetric exchange anisotropy may be present. In the strong spin-orbit limit, the Ir-O-Ir superexchange contribution consists of unfrustrated strong symmetric exchange anisotropy, and we suggest that spin-liquid behavior is unlikely. In the weak spin-orbit limit, and for strong spin-orbit and direct Ir-Ir exchange, the Hamiltonian consists of Heisenberg and DM interactions. The DM coupling is parametrized by a three component DM vector (which must be determined empirically). For a range of orientation of this vector, frustration is relieved and an ordered state occurs. For other orientations, even the classical ground states are very complex. We perform spin-wave and exact diagonalization calculations which suggest the persistence of a quantum spin liquid in the latter regime. Applications to Na$_4$Ir$_3$O$_8$ and broader implications are discussed. | |
| dc.description | 22 pages, 15 figures. submit to prb. New references are added | |
| dc.identifier | https://arxiv.org/abs/0806.1573 | |
| dc.identifier | http://arxiv.org/abs/0806.1573 | |
| dc.identifier | Phys. Rev. B 78, 094403 (2008) | |
| dc.identifier | doi:10.1103/PhysRevB.78.094403 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/170472 | |
| dc.subject | Strongly Correlated Electrons | |
| dc.title | Spin-orbit effects in Na$_4$Ir$_3$O$_8$, a hyper-kagomé lattice antiferromagnet | |
| dc.type | text |