ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
A method of measuring magnetoresistance (MR) in magnetic alloys is described in which fields comparable with those used in ac susceptibility methods, i.e., 〈5 G, are employed. To achieve the ultrasensitivity required, the MR voltage is entirely separated from the standing voltage present in zero field. The temperature stability of the standing voltage, crucial by normal methods, now becomes relatively unimportant. The separation of the MR voltage is achieved by using a unidirectional square-wave field which produces a square-wave MR signal which is amplified using a capacitor-transformer system feeding a lock-in amplifier. An investigation of the response of the input circuit was made and its limitations with respect to frequency and input resistance deduced. Precautions necessary for the successful operation of the apparatus are given together with examples of MR measured on some reentrant FeNi amorphous spin glasses. In these cases MR coefficients as small as 10−6 have been measured with a resolution of 10−8.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.352458
