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Ionic model for chromium, manganese, and iron impurities in copper

Technical Report ·
DOI:https://doi.org/10.2172/5350204· OSTI ID:5350204
The NMR frequencies of Cu atoms which are near neighbors to Cr atoms in dilute CuCr have an anomalous temperature dependence. Comparison with data from CuMn and CuFe which display the normal temperature dependence of a Curie-Weiss law lead to the conclusion that an ionic model of the magnetic impurity is necessary to explain the data. A model which assumes a definite 3d/sup n/ configuration with a definite L-S ground state and includes intraconfigurational energy level splittings due to a crystalline electric field and spin-orbit coupling is developed. The spin and orbital susceptibilities are calculated from the ionic structure and include the effects of the impurity electron-conduction electron mixing interaction in a perturbation treatment. The impurity hyperfine fields expected from the model are also calculated. Comparison of the model predictions with the data lead to the conclusion that (1) Cr and Mn have the structure which corresponds to the free ion divalent configuration while Fe corresponds to a monovalent configuration, (2) the crystal field at the site of the magnetic atoms is opposite of that usually assumed, and (3) the Weiss temperature of CuCr is 2.9 +- 1.0 K which is higher than most previously reported values but agrees within the experimental errors with a recently published bulk magnetic susceptibility measurement.
Research Organization:
Illinois Univ., Urbana, IL (United States)
Sponsoring Organization:
USDOE
DOE Contract Number:
EY-76-C-02-1198
OSTI ID:
5350204
Report Number(s):
COO--1198-1188
Country of Publication:
United States
Language:
English