DC AND AC MAGNETORESISTANCE MEASUREMENT TECHNIQUE FOR YBA2CU3O7-DELTATHIN-FILMS IN MEGAGAUSS FIELDS

We have developed a technique for measuring DC and AC magnetoresistanc e in very high magnetic fields in the megagauss range. We performed fo ur terminal DC transport measurements in megagauss fields by minimizin g the sample size and the area of the measurement circuit perpendicula r to the magnetic held. The use of a high frequency digital lock-in te chnique was found to improve the signal to noise ratio. Using this tec hnique, we measured the DC and AC magnetoresistance of YBa2Cu3O7-delta thin films at temperatures between 4.2 and 100 K in magnetic fields p arallel to the c-axis in magnetic fields up to 130 T. (C) 1998 Publish ed by Elsevier Science B.V. All rights reserved.