PARAMAGNETIC RESONANCE LINES AT LOW TEMPERATURE
HARVARD UNIV CAMBRIDGE MA CRUFT LAB
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A number of paramagnetic resonance line shapes have been analyzed and explained in terms of spin-spin interactions. It is shown that this technique may be an important supplement to other methods of investigating interaction in paramagnetic salts. The advantages of the line moment method at low temperature are 1 the exchange interaction can be found in sign and magnitude. Possible anisotropy of the exchange can be detected 2 exchange interaction between unlike neighbors only can be measured if the total exchange is known from other data, the exchange between like neighbors can be separated out and 3 the method works best at rather weak interactions where specific heat and susceptibility experiments are difficult to perform with sufficient accuracy. The disadvantages of the method are 1 a complex cryostat is needed and it is difficult to mount the sample inside the cavity in good heat contact with the He3 reservoir and 2 spherical samples are needed to avoid demagnetizing effects however, magnetostatic modes are easily excited in spheres, and this may obscure the true line shape.
- Atomic and Molecular Physics and Spectroscopy