The magnetic behaviour of titanium and vanadium hexaurea salts at low temperatures

1980 ◽  
Vol 33 (11) ◽  
pp. 2377 ◽  
Author(s):  
J Baker ◽  
BN Figgis
Keyword(s):  
Low Temperatures ◽  
Magnetic Behaviour ◽  
Ligand Field ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Coupling Constant ◽  
Ambient Temperatures ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Ligand Field Parameters

The magnetic susceptibility and anisotropy of the iodide and perchlorate salts of the hexaureatitanium(III) and hexaureavanadium(III) ions have been measured between liquid helium and ambient temperatures. The analysis of the data in terms of a model involving the angular and radial parts of the ligand field parameters, B0/2, B0/4 and B3/4, the spin-orbit coupling constant, λ, and the orbital reduction parameter, k, yields values supporting earlier studies, but having greater reliability and in better agreement with the optical absorption spectra. It is suggested that the low values deduced for k and λ/λ0 may be due to the operation of a dynamic Jahn-Teller effect.

Buckling on stanene: the role played by spin-orbit coupling and pseudo Jahn-Teller effect

MRS Advances ◽  
2017 ◽  
Vol 2 (29) ◽  
pp. 1563-1569 ◽  
Author(s):  
J. R. Soto ◽  
B. Molina ◽  
J. J. Castro
Keyword(s):  
Dft Calculations ◽  
Group Iv ◽  
Vibronic Coupling ◽  
Coupling Constants ◽  
Orbit Coupling ◽  
Teller Effect ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Jahn Teller ◽  
Jahn Teller Effect

ABSTRACTTwo-dimensional group IV layers beyond graphene, as silicene, germanene and the Sn-based stanene, have been recently synthesized by molecular beam epitaxy. Density Functional Theyory (DFT) calculations predict low-buckled structures for these 2D nanosheets, with a hexagonal honeycomb conformation, typical of the graphene-like surfaces. The buckling parameter δ increases from Si to Sn-based layers, with a maximum predicted of 0.92 Å for stanene. High-buckled structures for these materials resulted to be unstable. We have previously shown that for silicene and germanene, the origin of the buckled structure resides on the pseudo Jahn-Teller puckering distortion, resulting from non-adiabatic effects. It has been shown that hexagermabenzene, the single hexagonal unit of germanene, is subject to a strong vibronic coupling whose origin is the pseudo Jahn-Teller effect. This coupling resulted to be around ten times larger than the one obtained for hexasilabenzene. For stanene, an additional effect needs to be considered to understand the origin of buckling: the spin-orbit coupling (SOC). This SOC contributes to open an electronic band gap, enabling the use of these layers as nanoelectronic components. In this work, we present an analysis based on DFT in the Zeroth-Order Regular Approximation (ZORA) for both scalar relativistic and spin-orbit versions that quantify the influence of the spin-orbit coupling in the puckering of Sn6H6. Also, under the linear vibronic coupling model between the ground and the lowest excited states, we present the pseudo Jahn-Teller contribution. The scalar ZORA approximation is used to perform time-dependent DFT calculations to incorporate the low-energy excitations contributions. Our model leads to the determination of the coupling constants and predicts simultaneously the Adiabatic Potential Energy Surface behavior for the ground and excited states around the maximum symmetry point. These values allow us to compare the Jahn-Teller relevance in buckling with the other group IV layers.

Investigations Of The G Factors Of Fe+ In Mgo And Cao

2005 ◽  
Vol 60 (5) ◽  
pp. 366-368 ◽  
Author(s):  
Shao-Yi Wu ◽  
Hui-Ning Dong
Keyword(s):  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Octahedral Symmetry ◽  
Cluster Approach ◽  
Coupling Interaction ◽  
Perturbation Formula ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
G Factors

The g factors of Fe+ in MgO and CaO are theoretically investigated by the perturbation formula of the g factor of a 3d7 ion in cubic octahedral symmetry based on the cluster approach. By considering the partial quenching of the spin-orbit coupling interaction and the effective Land´e factor due to the dynamic Jahn-Teller effect (DJTE), the experimental g factors of the studied systems are reasonably interpreted. It can be suggested that the small g factors of the Fe+ centers in MgO and CaO can be likely attributed to the DJTE, rather than the covalency effect within the scheme of the static crystalfield model.

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