We manipulated the defect concentration in a $(\mathrm{\text{fluoranthene}}{)}_2{\mathrm{P}\mathrm{F}}_6$ crystal by proton irradiation through a periodic grid, resulting in a striped defect pattern. Spatially resolved pulsed $X$-band ESR analysis was used to quantify the resulting local defect concentrations, spin diffusion coefficients, and electron spin concentrations. The temperature dependence of the data proves that spin diffusion coefficient and Peierls transition can be tailored in a controlled way via the defect concentrations.

• Received 23 April 2004

DOI:https://doi.org/10.1103/PhysRevLett.94.016404