Messungen an Fe57 in Calciumaluminatferriten mit Hilfe des Mößbauer-Effekts

1966 ◽  
Vol 21 (6) ◽  
pp. 831-835 ◽  
Author(s):  
F. Wittmann ◽  
F. Pobell
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Electric Field Gradient ◽  
Field Gradient ◽  
Calcium Aluminate ◽  
Isomeric Shift ◽  
Temperature Range ◽  
Octahedral Sites ◽  
The Magnetic Field ◽  
Curie Temperatures

Measurements of the MÖSSBAUER-effect were made on Calcium-Aluminate-Ferrites [2 CaO · (Al2O3) x · (Fe2O3) 1-x] in the temperature range 4.2 °K ≦ Τ ≦ 700 °K. Ferrites with x=0, 1/3, 1/2 were made by sintering. The isomeric-shift is the same for the three ferrites, whereas the quadrupol-splitting is a function of x : ε1 (x=0) = (1.38 ± 0.05) mm/sec, ε2 (x=⅓) = (1.44 ± 0.05) mm/sec, ε3 (x =½) = (1.64 ± 0.05) mm/sec. The CURIE temperatures are Θ1 = (615 ± 4) °K, Θ2 = (490 ± 5) °K and Θ3= (398 ± 10) °K. For T=0 °K the extrapolated values of the magnetic field are independent of x : H0 (tet) = (505 ± 10) kOe and H0 (oct) = (555 ± 10) kOe at the tetrahedral and octahedral sites respectively. Under the assumption of an axial symmetric electric field gradient we calculated the angles between the electric field gradient and the magnetic field at the two lattice sites.

A 57Fe Mössbauer study of Fe2As: a magnetically induced electric-field-gradient asymmetry

1985 ◽  
Vol 63 (12) ◽  
pp. 1540-1547 ◽  
Author(s):  
D. G. Rancourt ◽  
J. M. Daniels ◽  
H-Y. Lam
Keyword(s):  
Electric Field ◽  
Electric Field Gradient ◽  
Field Gradient ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Antiferromagnetic Phase ◽  
Mössbauer Study ◽  
Temperature Range ◽  
Time Period ◽  
Two Factors

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.

Transient magnetic field and electric field gradient of fast H-like

1997 ◽  
Vol 359 (4) ◽  
pp. 377 ◽  
Author(s):  
U. Grabowy ◽  
K.-H. Speidel ◽  
J. Cub ◽  
H. Busch ◽  
H.-J. Wollersheim ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Electric Field Gradient ◽  
Field Gradient ◽  
Transient Magnetic Field

Pure NQR Quantum Computing

2002 ◽  
Vol 57 (6-7) ◽  
pp. 315-319 ◽  
Author(s):  
G. B. Furman ◽  
S. D. Goren
Keyword(s):  
Magnetic Field ◽  
Quantum Computing ◽  
Energy Spectrum ◽  
External Magnetic Field ◽  
Electric Field ◽  
Radio Frequency ◽  
Electric Field Gradient ◽  
Field Gradient ◽  
Energy Levels ◽  
Resonance Transition

It is shown that pure NQR can be utilized as a platform for quantum computing without applying a high external magnetic field. By exciting each resonance transition between quadrupole energy levels with two radio-frequency fields differing in phase and direction, the double degeneracy of the spin energy spectrum in an electric field gradient is removed. As an example, in the case of I = 7/2 (nuclei 133Cs or 123Sb) the energy spectrum has eight levels which can be used as three qubits.

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