Narrow Zero-Field Tunneling Resonance in Triclinic Mn${}_{12}$ Acetate Ribbons

Abstract

We report synthesis, structural characterization, and magnetic measurements of amorphous Mn${}_{12}$-acetate ribbons with a triclinic short-range crystal order not previously seen in experiment. The ribbons exhibit the same structure of Mn${}_{12}$ molecules and the same positions of tunneling resonances on the magnetic field as a conventional tetragonal Mn${}_{12}$-acetate crystal. However, the width of the zero-field resonance is by at least one order of magnitude smaller, indicating very small inhomoge- neous broadening due to dipolar and nuclear fields. Possible origins of this effect are discussed.

6 pages, 10 figures