Asymmetric Lineshape due to Inhomogeneous Broadening of the Crystal-Field Transitions in Mn12ac Single Crystals

TL;DR

This study investigates how the lineshape of crystal-field transitions in Mn12ac single crystals varies with magnetic history, revealing symmetric Gaussian lines in non-magnetized states and asymmetric lines in magnetized states due to inhomogeneous broadening and susceptibility effects.

Contribution

It provides a quantitative explanation for the asymmetric lineshape observed in magnetized states, linking it to inhomogeneous broadening and magnetic susceptibility contributions.

Findings

Lineshapes are symmetric and Gaussian in non-magnetized states.

Lineshapes become asymmetric in magnetized states.

Inhomogeneous broadening and susceptibility effects explain the asymmetry.

Abstract

The lineshape of crystal-field transitions in single crystals of Mn12ac molecular magnets is determined by the magnetic history. The absorption lines are symmetric and Gaussian for the non-magnetized state obtained by zero-field cooling (zfc). In the magnetized state which is reached when the sample is cooled in a magnetic field (fc), however, they are asymmetric even in the absence of an external magnetic field. These observations are quantitatively explained by inhomogeneous symmetrical (Gaussian) broadening of the crystal-field transitions combined with a contribution of off-diagonal components of the magnetic susceptibility to the effective magnetic permeability.