Soham Manni

Relevance of the Heisenberg-Kitaev model for the honeycomb lattice iridates A2IrO3.

Combining thermodynamic measurements with theoretical calculations we demonstrate that the iridates A2IrO3 (A=Na, Li) are magnetically ordered Mott insulators where the magnetism of the effective spin-orbital S=1/2 moments can be captured by a Heisenberg-Kitaev (HK) model with interactions beyond nearest-neighbor exchange. Experimentally, we observe an increase of the Curie-Weiss temperature from θ≈-125  K for Na2IrO3 to θ≈-33  K for Li2IrO3, while the ordering temperature remains roughly the same T(N)≈15  K. Using functional renormalization group calculations we show that this evolution of θ and T(N) as well as the low temperature zigzag magnetic order can be captured within this extended HK model. We estimate that Na2IrO3 is deep in a magnetically ordered regime, while Li2IrO3 appears to be close to a spin-liquid regime.

Crystal-field splitting and correlation effect on the electronic structure of A2IrO3.

The electronic structure of the honeycomb lattice iridates Na(2)IrO(3) and Li(2)IrO(3) has been investigated using resonant inelastic x-ray scattering (RIXS). Crystal-field-split d-d excitations are resolved in the high-resolution RIXS spectra. In particular, the splitting due to noncubic crystal fields, derived from the splitting of j(eff)=3/2 states, is much smaller than the typical spin-orbit energy scale in iridates, validating the applicability of j(eff) physics in A(2)IrO(3). We also find excitonic enhancement of the particle-hole excitation gap around 0.4 eV, indicating that the nearest-neighbor Coulomb interaction could be large. These findings suggest that both Na(2)IrO(3) and Li(2)IrO(3) can be described as spin-orbit Mott insulators, similar to the square lattice iridate Sr(2)IrO(4).

Extremely large magnetoresistance and Kohler's rule in PdSn4 : A complete study of thermodynamic, transport, and band-structure properties

A new type of a topological quantum structure was identified recently in PtSn

BaSn2 : A wide-gap strong topological insulator

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Isotope Effect on Electron-Phonon Interaction in Multiband Superconductor MgB2

as a Dirac node arc feature on the surface. More importantly, PtSn

Growth and characterization of BaZnGa

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Effect of pressure on the physical properties of the superconductor NiBi3.

shows extremely large magnetoresistance (XMR). PdSn

An inverse Ruddlesden-Popper nitride Ca7(Li1−xFex)Te2N2 grown from Ca flux

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Extremely large magnetoresistance and Kohler's rule in PdSn 4 : a comprehensive study.

is isostructural with PtSn

Tuning the Vortex Lattice Phase Diagram of MgB 2 through Doping

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