We investigated the electronic structure of 5d transition-metal oxide Sr2IrO4 using angle-resolved photoemission, optical conductivity, x-ray absorption measurements, and first-principles band calculations. The system was found to be well described by novel effective total angular momentum Jeff states, in which the relativistic spin-orbit coupling is fully taken into account under a large crystal field. Despite delocalized Ir 5d states, the Jeff states form such narrow bands that even a small correlation energy leads to the Jeff=1/2 Mott ground state with unique electronic and magnetic behaviors, suggesting a new class of Jeff quantum spin driven correlated-electron phenomena.

/pdf/novel-jeff-1-2-mott-state-induced-by-relativistic-spin-orbit-2kiopkz7fu.pdf

Novel Jeff=1/2 Mott state induced by relativistic spin-orbit coupling in Sr2IrO4.

Small, light weight and multifunctional electronic components are attracting much attention because of the rapid growth of the wireless communication systems and microwave products in the consumer electronic market. The component manufacturers are thus forced to search for new advanced integration, packaging and interconnection technologies. One solution is the low temperature cofired ceramic (LTCC) technology enabling fabrication of three-dimensional ceramic modules with low dielectric loss and embedded silver electrodes. During the past 15 years, a large number of new dielectric LTCCs for high frequency applications have been developed. About 1000 papers were published and ∼500 patents were filed in the area of LTCC and related technologies. However, the data of these several very useful materials are scattered. The main purpose of this review is to bring the data and science of these materials together, which will be of immense help to researchers and technologists all over the world. The comme...

Low loss dielectric materials for LTCC applications: a review

B-cation arrangements in double perovskites

Progress and prospective of solid-state lithium batteries

A2B′B″O6 perovskites: A review

Dielectric properties of a-site deficient perovskite-type lanthanum-calcium-titanium oxide solid solution system [(1 − x)La23TiO3 − xCaTiO3 (0.1 ≤ x ≤ 0.96)]

Lithium ion conductivity in the perovskite-type LiTaO3-SrTiO3 solid solution

Electrical conductivity and metal-nonmetal transition in the Perovskite-related layered system Can+1TinO3n+1-δ (n = 2,3, and ∞)

Oxide cathode with perovskite structure for rechargeable lithium batteries

The effects of Ca and Ba substitutions for Sr on the structure and properties of ${\mathrm{Sr}}_{2}$${\mathrm{IrO}}_{4}$ were studied. Increase in the Ir-O(2)-Ir bond angle in the ${\mathrm{IrO}}_{2}$ plane was found after the substitutions of Ca and Ba for Sr. However, the Ir-O(2) distance is found to be unchanged by the Ba substitution, while it decreases by the Ca substitution. Regardless of these structural changes, the magnetic transition temperature at 240 K was found to be unchanged. Semiconductive behavior of the resistivity was found for all compounds with the increase in activation energy above 200 K. Both the electrical resistivity and the Seebeck coefficient showed no remarkable anomaly around the magnetic transition temperature.

Tetsuro Nakamura

Papers

Dielectric properties of a-site deficient perovskite-type lanthanum-calcium-titanium oxide solid solution system [(1 − x)La23TiO3 − xCaTiO3 (0.1 ≤ x ≤ 0.96)]

Lithium ion conductivity in the perovskite-type LiTaO3-SrTiO3 solid solution

Electrical conductivity and metal-nonmetal transition in the Perovskite-related layered system Can+1TinO3n+1-δ (n = 2,3, and ∞)

Oxide cathode with perovskite structure for rechargeable lithium batteries

Structure and magnetic properties of Sr2-xAxIrO4 (A=Ca and Ba).