Search for thermometers with low magnetoresistive effects: platinum-cobalt alloy
✍ Scribed by F. Pavese; P. Cresto
- Book ID
- 103049790
- Publisher
- Elsevier Science
- Year
- 1984
- Tongue
- English
- Weight
- 606 KB
- Volume
- 24
- Category
- Article
- ISSN
- 0011-2275
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✦ Synopsis
Measurements performed on thermometers made of dilute ferromagnetic alloys of Pt with 0.45, 0.50, 0.75, 1.06 and 2.15 at%Co, in the temperature range 2-28 K and in magnetic fields up to 6 T showed a large region of negative magnetoresistivity that limits the magnetic error at low temperatures and field values. With 0.5 at%Co or less, the change of the magnetic error with T and B was smooth, while a magnetic transition has been observed with higher cobalt concentrations. Curie temperature has been found to occur at 6.0 I~ 14.2 K and, by extrapolation, 32 K for alloys with 0.75, 1.06, and 2. 15 at%Co respectively. The transition resulted in a second order discontinuity of the R-T characteristics at B = 0 and B = 3.8 + 0.2 T with 0.75 at%Co andS.0 ± 0.5 Twith 1.06 at%Co, while for other field values the discontinuity was first-order. Hence, this alloy can be used for thermometry only with very low cobalt concentrations: with 0.3 at%Co it would be possible to limit the magnetic error within ±0.2 K up to 2 T and down to 5 K.