LOCAL PROBE (170YB3+) MEASUREMENTS OF MAGNETIC-FIELDS IN YBA2CU3OX

We introduce the technique of studying the field dependence of the electro-nuclear energy levels of a rare earth to measure the magnetic field present at the rare earth/yttrium site in YBa2Cu3Ox. Measurements were made by170Yb Mössbauer spectroscopy. The hyperfine spectrum of the ground state Kramers doublet for Yb3+ ions diluted into this matrix is sensitive to fields in the range 100 to 2000G. Flux penetration and trapping at the local site level have been measured in superconducting samples. A molecular field exists on the rare earth site in non superconducting samples suggesting that the ordered Cu2 magnetic moments are intrinsically non colinear. © 1990 J.C. Baltzer A.G., Scientific Publishing Company.