RESUMO
Using organic materials in spintronic devices raises a lot of expectation for future applications due to their flexibility, low cost, long spin lifetime, and easy functionalization. However, the interfacial hybridization and spin polarization between the organic layer and the ferromagnetic electrodes still has to be understood at the molecular scale. Coupling state-of-the-art spin-polarized scanning tunneling spectroscopy and spin-resolved ab initio calculations, we give the first experimental evidence of the spin splitting of a molecular orbital on a single non magnetic C(60) molecule in contact with a magnetic material, namely, the Cr(001) surface. This hybridized molecular state is responsible for an inversion of sign of the tunneling magnetoresistance depending on energy. This result opens the way to spin filtering through molecular orbitals.
Assuntos
Fulerenos/química , Modelos Químicos , Modelos Moleculares , Simulação por Computador , Impedância Elétrica , Campos MagnéticosRESUMO
Several tens of chromium layers were deposited at 250 °C on a Cr(001) surface and investigated by spin-polarized scanning tunneling microscopy (SP-STM), Auger electron spectroscopy (AES) and scanning tunneling spectroscopy (STS). Chromium is found to grow with a mound-like morphology resulting from the stacking of several monolayers which do not uniformly cover the whole surface of the substrate. The terminal plane consists of an irregular array of Cr islands with lateral sizes smaller than 20 × 20 nm(2). Combined AES and STS measurements reveal the presence of a significant amount of segregants prior to and after deposition. A detailed investigation of the surface shows that it consists of two types of patches. Thanks to STS measurements, the two types of area have been identified as being either chromium pure or segregant rich. SP-STM experiments have evidenced that the antiferromagnetic layer coupling remains in the chromium mounds after deposition and is not significantly affected by the presence of the segregants.
