Periodic Reporting for period 1 - ELECTRA (ELEctrically ConTRolled magnetic Anisotropy)
Berichtszeitraum: 2022-06-01 bis 2023-11-30
Control over magnetic properties, and in particular over magnetic anisotropy, is key to storage devices for writing, reading and accessing data. In contrast to bulk materials, molecules offer opportunities for unprecedented high density, speed and efficiency. The electron spin of atoms generate a small magnetic field that can be controlled through external magnetic fields. However strong, locally applicable and rapidly switchable electric fields are the next technological frontier. Control enhancement will lead to smaller, more efficient and low-energy devices with numerous applications. The EU-funded ELECTRA project will develop a pioneering experimental technique to study spin-electric effects on both single cruystals and thin films. Combining theoretical and experimental approaches, the project will avail new insights into spin-electric effects for a rational molecular design.
The project started on June 1st 2022. The synthetic part of the project has been immediately started and the synthesis of several derivatives has been performed. Both transition-metal and lanthanide based molecules have been synthesized. Due to the difficulties in obtaining acentric structures, several new chiral ligands have been synthesized and exploited for the coordination. The magnetic properties (and particularly the magnetic anisotropy) of the derivatives has been staudied using a combination of powder based and single crystal based techniques. Models based on the Crystal Field or Spin Hamiltonian formalisms have been developed to successfully rationalize all the experimental evidences. In parallel, ab initio calculations have been performed on selected derivatives to understand the origin of their behaviour. The development of the experimental technique to measure spin-electric effect via torque magnetometry is in progress. In the meantime, we started studying the spin-electric effect using Electric Field Modulated EPR, readily available at the HI.
So far we have achieved several results beyond the state of the art, especially regarding the magnetic anisotropy of lanthanide complexes.
1) We have shown for the first time that the magnetic anisotropy switch phenomenon could be preserved and observed on molecular layers. This constitutes a cornerstone result in the field of magnetochemistry because it paves the way to use the magnetic anisotropy switches in real spintronic devices. The system constitutes an ideal platform to study SE effects on the surface, however at the moment we are not aware of technique with sufficient sensitivity to do so. We will test the sensitivity newly designed experimental setup and assess if such measurement will be feasible.
2) We have shown that the Dy(ODA) complex exhibits a strong SE effect (the second strongest value ever observed after HoPOM20). Moreover, we have unequivocally assessed the role of chirality in the SE effect: reversing the chirality reverses the SE effect. The result is however not published yet because the ab initio calculations cannot reproduce the experimentally observed magnitude. We plan on refining the calculations including more effects.
3) We have shown that the water molecule is the key ligand to tune the magnetic anisotropy of the LnDOTA complexes. Our experimental investigation proofs that the water removal causes a change of magnetic anisotropy in three derivatives (Ln = Tb, Dy, Ho) from easy axis to easy plane. Also, we have developed an innovative synthetic protocol based on ionic strength and packing effects to remove the water ligand using water as a solvent.
1) We have shown for the first time that the magnetic anisotropy switch phenomenon could be preserved and observed on molecular layers. This constitutes a cornerstone result in the field of magnetochemistry because it paves the way to use the magnetic anisotropy switches in real spintronic devices. The system constitutes an ideal platform to study SE effects on the surface, however at the moment we are not aware of technique with sufficient sensitivity to do so. We will test the sensitivity newly designed experimental setup and assess if such measurement will be feasible.
2) We have shown that the Dy(ODA) complex exhibits a strong SE effect (the second strongest value ever observed after HoPOM20). Moreover, we have unequivocally assessed the role of chirality in the SE effect: reversing the chirality reverses the SE effect. The result is however not published yet because the ab initio calculations cannot reproduce the experimentally observed magnitude. We plan on refining the calculations including more effects.
3) We have shown that the water molecule is the key ligand to tune the magnetic anisotropy of the LnDOTA complexes. Our experimental investigation proofs that the water removal causes a change of magnetic anisotropy in three derivatives (Ln = Tb, Dy, Ho) from easy axis to easy plane. Also, we have developed an innovative synthetic protocol based on ionic strength and packing effects to remove the water ligand using water as a solvent.