Spin spatial inhomogeneity

STM experiments suggested that in these materials at low temperatures one had intrinsic electronic spatial inhomogeneity. This conclusion is consistent with a proposal by Slichter on how one might reconcile the results of NMR experiments (a local probe) that seemed to require commensurate spin fluctuation peaks and INS experiments (a global probe) that show an incommensurate peak Slichter proposed that one is observing discommensuration in the 2-1-4 (and possibly other cuprates), with regions... 

A simple example of an inhomogeneously broadened line is a resonance broadened by inhomogeneity of the applied dc magnetic field. If the applied field has a spatial inhomogeneity, otherwise identical spins in different parts of the sample will have slightly different resonance frequencies. As a result, the FID will be much shorter than that determined by... 

It is this spin diffusion phenomenon that is used to provide an estimate of spatial dimensions in motionally inhomogeneous systems. The idea simply being that observation of the time required for equilibration of two regions in a spin system gives a measure of the dimension involved in the transport process, when the diffusion coefficient is known. 

Where 8 and d2 are, respectively, the intrinsic 7j and an experimental factor accounting for a spatially dependent imperfect spin inversion. In some cases, generic parametric models (e.g., polynomial series) can be used to identify complicated responses, such as the free induction decay (FID) signal dephasing induced by the presence of magnetic field inhomogeneities.3... 

---