Spin-orbit-induced electric-field gradient of Au in Ni

2003 ◽  
Vol 67 (13) ◽  
Author(s):  
G. Seewald ◽  
E. Zech ◽  
E. Hagn ◽  
H.-J. Körner ◽  
C. Tramm ◽  
...  
1985 ◽  
Vol 63 (12) ◽  
pp. 1540-1547 ◽  
Author(s):  
D. G. Rancourt ◽  
J. M. Daniels ◽  
H-Y. Lam

The 57Fe Mössbauer spectrum of Fe2As has been measured in the temperature range 25–456 K. Evidence is found for two factors that affect the spectrum and that had been neglected in earlier investigations. These are (i) spin relaxation in a time period that is short compared with the characteristic Mössbauer measurement time and (ii) an anisotropy induced in the electric field gradient at the 57Fe nuclei, by the Weiss molecular field, via the spin orbit coupling. Taking these factors into account, we find that the Mössbauer spectra give consistent and physically reasonable parameters over the whole temperature range. There is also agreement with previous neutron-diffraction studies in that the spins in the antiferromagnetic phase are perpendicular to the c axis. The disagreements reported in earlier studies are seen to arise from a neglect of these factors.


Author(s):  
Samuel Silva dos Santos ◽  
Michel L. Marcondes ◽  
Ivan P. Miranda ◽  
Pedro Rocha-Rodrigues ◽  
Lucy Vitória Credidio Assali ◽  
...  

An ab-initio study for several hybrid improper ferroelectric (HIF) materials in the Ruddlesden-Popper phases and double perovskites structures is here presented. The focus is on the correlation between the electric...


2007 ◽  
Vol 62 (12) ◽  
pp. 711-715 ◽  
Author(s):  
Ahmad Seif ◽  
Mahmoud Mirzaei ◽  
Mehran Aghaie ◽  
Asadollah Boshra

Density functional theory (DFT) calculations were performed to calculate the electric field gradient (EFG) tensors at the sites of aliminium (27Al) and nitrogen (14N) nuclei in an 1 nm of length (6,0) single-walled aliminium nitride nanotube (AlNNT) in three forms of the tubes, i. e. hydrogencapped, aliminium-terminated and nitrogen-terminated as representatives of zigzag AlNNTs. At first, each form was optimized at the level of the Becke3,Lee-Yang-Parr (B3LYP) method, 6-311G∗∗ basis set. After, the EFG tensors were calculated at the level of the B3LYP method, 6-311++G∗∗ and individual gauge for localized orbitals (IGLO-II and IGLO-III) types of basis sets in each of the three optimized forms and were converted to experimentally measurable nuclear quadrupole resonance (NQR) parameters, i. e. quadrupole coupling constant (qcc) and asymmetry parameter (ηQ). The evaluated NQR parameters revealed that the considered model of AlNNT can be divided into four equivalent layers with similar electrostatic properties.With the exception of Al-1, all of the three other Al layers have almost the same properties, however, N layers show significant differences in the magnitudes of the NQR parameters in the length of the nanotube. Furthermore, the evaluated NQR parameters of Al-1 in the Al-terminated form and N-1 in the N-terminated form revealed the different roles of Al (base agent) and of N (acid agent) in AlNNT. All the calculations were carried out using the GAUSSIAN 98 package program.


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