Electronically Mediated Magnetic Anisotropy in Vibrating Magnetic Molecules

TL;DR

This paper investigates how electronic interactions and temperature biases influence magnetic anisotropy in vibrating magnetic molecules within ferromagnetic junctions, revealing controllable magnetic states.

Contribution

It demonstrates how temperature and voltage biases can switch the magnetic anisotropy in vibrating molecules, highlighting the role of ferromagnet properties and coupling strength.

Findings

Anisotropy can switch from easy axis to easy plane with temperature or voltage bias.

Weaker ferromagnet properties primarily determine the anisotropy character.

Strong coupling locks the anisotropy into easy plane magnetism.

Abstract

We address the electronically induced anisotropy field acting on a spin moment comprised in a vibrating magnetic molecule located in the junction between ferromagnetic metals. Under weak coupling between the electrons and molecular vibrations, the nature of the anisotropy can be changed from favoring a high spin (easy axis) magnetic moment to a low spin (easy plane) by applying a temperature difference or a voltage bias across the junction. For unequal spin-polarizations in the ferromagnetic metals it is shown that the character of the anisotropy is essentially determined by the properties of the weaker ferromagnet. By increasing the temperature in this metal, or introducing a voltage bias, its influence can be suppressed such that the dominant contribution to the anisotropy is interchanged to the stronger ferromagnet. With increasing coupling strength between the molecular vibrations and the electrons, the nature of the anisotropy is locked into favoring easy plane magnetism.