Spin fluctuations in isotropic ferromagnets near TC

✍ Scribed by P. Böni

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 489 KB
• Volume: 192
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/0921-4526(93)90111-i

✦ Synopsis

By means of polarized neutrons it is possible to measure different magnetic spin excitation modes in isotroplc ferromagnets. The data from EuS shows that the demagnetizing fields have a profound effect on the spin excitations below and above T c. In particular they prevent the long-wavelength spin fluctuations ~ II q from diverging at T c. This behaviour is reflected in the dynamics of the paramagnetic fluctuations and the spin waves below T c. The modes with longitudinal polarization are more damped than their transverse counterparts. Above T c the relaxation rates follow rather precisely the dipolar dynamic scaling functions calculated recently by mode-coupling theory. Below T c, the parallel magnetization fluctuations, ~S I] M, are significantly stronger in EuS than in Ni.