LOW-TEMPERATURE SPIN-WAVE RESONANCE AT 3000 AND 4000 Mc/sec IN A PERMALLOY HAVING NEARLY ZERO MAGNETOCRYSTALLINE ANISOTROPY
The observation of spin-wave resonance in Permalloy samples of exremely low anisotropy has been exended to liquid nitrogen temperature. Measurements at both room and liquid nitrogen temperature hnve been carried out at 3000 and at 4000 Mc/sec. At room temperature the complete experimental resonance curve can be explained at both frequencies on the basis of the spin-wave resonance theory of Ament and Rado by using an average exchange stiffness constant, A, of (3 3 plus or minus 0.5) x 10/sup -6/ erg/cm and a g factor of 2.06 plus or minus 0.01. The agreement between experiment and theory would be destroyed if a Landau-Lifshitz or Bloch damping term were included. The theory of Ament and Hado predicts thnt as the temperature is lowered the exchnnge broadening of the resonance line increases and the resonance tield decreases. Both effects have been observed qualitatively but neither is as would be expected from the theory. It has been found that at a given temperature the plot of the imaginary versus real part of the equivalent permeability at 3000 Mc/sec differs only by a scale factor from the corresponding plot at 4000 Mc/sec. At room temperature the above frequency increase causes a decrease in the permeabilities of 30% from the corresponding values at 3000 Mc/sec, as compared to a predicted 15% decrease. The discrepancy between theory and experiment at the low temperature is about the same at one frequency as at the other. Since the corresponding resonance fields differ by a factor of two, any effects due to incomplete saturation seem to be ruled out. (auth)
- Research Organization:
- U.S. Naval Research Lab., Washington
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-12-007874
- OSTI ID:
- 4334270
- Journal Information:
- Journal of Applied Physics (U.S.), Vol. Vol: 29; Other Information: Orig. Receipt Date: 31-DEC-58
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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