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Observation of large-scale nuclear phase modulation effects

Thesis/Dissertation ·
OSTI ID:7001619
The excitation of coherent transients in Moessbauer spectra has been previously limited to a low range of frequencies by the high powers required to modulate the nuclear phases. Reported here is an eleven-orders-of magnitude increase in the efficiency through which such phenomena can be produced. Magnetic modulation of the quantum phases of {sup 57}Fe nuclei in paramagnetic media has been produced by spin waves of large amplitude transported from ferromagnetic sources. Excited on one end by the oscillating magnetization of a strip of ferromagnetic Ni, the absorber foil showed the strong development of sidebands at the other end where mechanical vibrations were shown to contribute less than 1% of the signal. It was further demonstrated that spin waves can transport nuclear phase modulation effects through a paramagnetic bridge which connects physically separated Ni source foils and the {sup 57}Fe enriched stainless which was used to detect the effect. It was found that sidebands resulting from nuclear phase modulation are not observed in the Moessbauer absorption spectra of {sup 119}Sn when thin foils of diamagnetic tin are used as the absorber. However, the effect can be observed by embedding the tin nuclei into ferromagnetic or antiferromagnetic materials. This was demonstrated in the magnetic compounds FeSn{sub 2} and NiSn.
Research Organization:
Texas Univ., Dallas, TX (USA)
OSTI ID:
7001619
Country of Publication:
United States
Language:
English