Temperature dependence of the magnetic parameters in the Sm2−xGdxCo17−yMny compounds

Abstract
The series of compounds Sm2−xGdxCo17−yMny was studied with regard to its suitability for employment as permanent magnet material in microwave/millimeter‐wave traveling‐wave tubes (TWT′s). The pertinent properties investigated are saturation magnetization, 4πMs, temperature coefficient of 4πMs, α, and anisotropy field, HA. The composition ranges investigated were from x =0 to 0.6 and y =0 to 2. Values of 4πMs at 25 C ranged from 12.8 kG for x = 0, y = 1 to 9.4 kG for x = 0.6, y = 2. For the compounds studied, maximum HA occurs at y = 1 for x = 0. The compounds, whose formulas contain a single atom of manganese, were found to yield excellent temperature compensation via Gd substitution in the range +20 to +150 C with the best coefficient occurring in Sm1.6Gd0.4Co16Mn for which α = −0.008%/C (4πMs=10.5 kG).