Vibration-induced modulation of magnetic anisotropy in a magnetic molecule

TL;DR

This paper theoretically investigates how molecular vibrations influence magnetic anisotropy in magnetic molecules, affecting their transport properties and spectrum, with potential control via mechanical deformation.

Contribution

It introduces a model showing vibrationally induced renormalization of magnetic anisotropy parameters in magnetic molecules, linking vibrations to transport behavior.

Findings

Vibrations cause shifts and crossings in magnetic spectra.

Vibrational coupling can induce transport blockade.

Mechanical deformation controls spin-vibration interactions.

Abstract

We theoretically analyze the spectrum of a magnetic molecule when its charge and spin can couple to the molecular vibrations. More specifically, we show that the interplay between charge-vibron and spin-vibron coupling leads to a renormalization of the magnetic anisotropy parameters of the molecule. This effect is discussed for a model device consisting of an individual magnetic molecule embedded in a junction. We study the transport properties of the device and illustrate how the differential conductance is affected by the vibrationally induced renormalization of the magnetic anisotropy. Depending on the total molecular spin and the bare (intrinsic) magnetic anisotropy, the induced modulation can lead to visible shifts and crossings in the spectrum, and it can even be the cause of a transport blockade. It is therefore of particular interest to use mechanically controllable break junctions, since in such a case, the relevant coupling between the molecular spin and vibrations can be controlled via deformations of the molecule when stretching or compressing the junction.