ISSN:
1089-7623
Source:
AIP Digital Archive
Topics:
Physics
,
Electrical Engineering, Measurement and Control Technology
Notes:
Two methods have been developed to measure variations with magnetic field of electrical resistances in the range 0.1 nΩ–1 μΩ, for applied magnetic fields up to 3 T, and for temperatures less than 9 K. The first method provides direct access to R(H). Its absolute sensitivity is 3×10−14 V/(square root of)Hz with a short circuit at input. It becomes on a 1 μΩ sample: 6×10−14 V/(square root of)Hz in zero field, and 2×10−12 V/(square root of)Hz under 3 T. Averaging the signal over 100 s, the sensitivity is 6×10−15 V in zero field and 2×10−13 V under 3 T. In terms of resistance, using a sensing current of 100 mA, it corresponds to a sensitivity of 6×10−14 Ω in zero field and 2×10−12 Ω in the maximum field. The reproducibility of this method is 0.3%. The second method is a sinusoidal field modulation technique giving the field derivative of the resistance: dR/dH. It has the same absolute sensitivity as the R(H) method and it achieves ultrahigh resolution. It is sensitive to variations of the resistance as small as 6×10−14 Ω in zero field and 2×10−12 Ω in 3 T independent of the absolute resistance of the sample, thus the resulting resolution ΔR/R is, for example, 6×10−8 in zero field and 2×10−6 in the maximum field for a 1 μΩ sample. To demonstrate the high sensitivity of the setups, we measured the magnetoresistance of a magnetic multilayer with the current applied perpendicular to the multilayer plane. © 1996 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1147120
