Abstract
The possibility to graft nano-objects directly on its surface makes graphene particularly appealing for device and sensing applications. Here we report the design and the realization of a novel device made by a graphene nanoconstriction decorated with TbPc(2) magnetic molecules (Pc = phthalocyananine), to electrically detect the magnetization reversal of the molecules in proximity with graphene. A magnetoconductivity signal as high as 20% is found for the spin reversal, revealing the uniaxial magnetic anisotropy of the TbPc(2) quantum magnets. These results depict the behavior of multiple-field-effect nanotransistors with sensitivity at the single-molecule level.
Highlights
The possibility to graft nano-objects directly on its surface makes graphene appealing for device and sensing applications
The presence of a high-spin state exhibiting a magnetic anisotropy barrier leads to the observation of quantum tunneling of the magnetization (QTM)
The crossing between two molecular levels can be studied at finite field and tuned in different crystallographic directions in the laboratory.[3]. While these issues have been intensively studied in ensembles of identical molecules, the observation of the magnetization reversal on one or very-few molecules has not been reported yet
Summary
(d) False-color SEM image of the device presented in the text. SiO2 substrate and etched graphene are colored in purple. If a magnetic field is applied within the graphene sheet, finite magnetoconductivity appears only for backgate voltage values that drive the nanoconstriction to conductivity resonances. The J state of Tb(III) may change either the energy level of available excited state within the dot or the spin state of such levels Keeping these mechanisms in mind, we can describe how the conductivity G of the nanoconstriction (taking for instance the curve in Figure 3 as a reference) becomes sensitive to the magnetization reversal of the molecules. For further increase of the field, all the molecules reverse their magnetic moments, becoming again fully polarized (in the opposite direction with respect to the initial step) at Hc. The forbidden channels become accessible again, and the conductivity is restored to the initial value Gsat. This material is available free of charge via the Internet at http:// pubs.acs.org
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