Microscopic study of spin-orbit-induced Mott insulator in Ir oxides

Motivated by recent experiments of a novel 5$d$ Mott insulator in Sr$_2$IrO$_4$, we have studied the two-dimensional three-orbital Hubbard model with a spin-orbit coupling $\lambda$. The variational Monte Carlo method is used to obtain the ground state phase diagram with varying a on-site Coulomb interaction $U$ as well as $\lambda$. It is found that the transition from a paramagnetic metal to an antiferromagnetic (AF) insulator occurs at a finite $U=U_{\mathrm{MI}}$, which is greatly reduced by a large $\lambda$, characteristic of 5$d$ electrons, and leads to the "spin-orbit-induced" Mott insulator. It is also found that the Hund's coupling induces the anisotropic spin exchange and stabilizes the in-plane AF order. We have further studied the one-particle excitations using the variational cluster approximation, and revealed the internal electronic structure of this novel Mott insulator. These findings are in agreement with experimental observations on Sr$_2$IrO$_4$, and qualitatively different from those of extensively studied 3$d$ Mott insulators.Comment: 5 pages, 3 figures; accepted for publication in Phys. Rev. Let

Basic Study on Sediment Behavior in the Chiyoda Experimental Channel

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Complete nucleotide sequence of the Cryptomeria japonica D. Don. chloroplast genome and comparative chloroplast genomics: diversified genomic structure of coniferous species

<p>Abstract</p> <p>Background</p> <p>The recent determination of complete chloroplast (cp) genomic sequences of various plant species has enabled numerous comparative analyses as well as advances in plant and genome evolutionary studies. In angiosperms, the complete cp genome sequences of about 70 species have been determined, whereas those of only three gymnosperm species, <it>Cycas taitungensis</it>, <it>Pinus thunbergii</it>, and <it>Pinus koraiensis </it>have been established. The lack of information regarding the gene content and genomic structure of gymnosperm cp genomes may severely hamper further progress of plant and cp genome evolutionary studies. To address this need, we report here the complete nucleotide sequence of the cp genome of <it>Cryptomeria japonica</it>, the first in the Cupressaceae sensu lato of gymnosperms, and provide a comparative analysis of their gene content and genomic structure that illustrates the unique genomic features of gymnosperms.</p> <p>Results</p> <p>The <it>C. japonica </it>cp genome is 131,810 bp in length, with 112 single copy genes and two duplicated (<it>trn</it>I-CAU, <it>trn</it>Q-UUG) genes that give a total of 116 genes. Compared to other land plant cp genomes, the <it>C. japonica </it>cp has lost one of the relevant large inverted repeats (IRs) found in angiosperms, fern, liverwort, and gymnosperms, such as <it>Cycas </it>and <it>Gingko</it>, and additionally has completely lost its <it>trn</it>R-CCG, partially lost its <it>trn</it>T-GGU, and shows diversification of <it>acc</it>D. The genomic structure of the <it>C. japonica </it>cp genome also differs significantly from those of other plant species. For example, we estimate that a minimum of 15 inversions would be required to transform the gene organization of the <it>Pinus thunbergii </it>cp genome into that of <it>C. japonica</it>. In the <it>C. japonica </it>cp genome, direct repeat and inverted repeat sequences are observed at the inversion and translocation endpoints, and these sequences may be associated with the genomic rearrangements.</p> <p>Conclusion</p> <p>The observed differences in genomic structure between <it>C. japonica </it>and other land plants, including pines, strongly support the theory that the large IRs stabilize the cp genome. Furthermore, the deleted large IR and the numerous genomic rearrangements that have occurred in the <it>C. japonica </it>cp genome provide new insights into both the evolutionary lineage of coniferous species in gymnosperm and the evolution of the cp genome.</p