Kondo effect in binuclear metal-organic complexes with weakly interacting spins

Article

关键词: ELECTRONIC-STRUCTURE;    MOLECULE;    STATES;    MAGNETORESISTANCE;    RESONANCE;    TRANSPORT;    CROSSOVER;    SPECTRA;    MAGNETS;    SURFACE;   

DOI  :  10.1103/PhysRevB.91.195424

来源: SCIE

【 摘 要 】

We report a combined experimental and theoretical study of the Kondo effect in a series of binuclear metalorganic complexes of the form [(Me(hfacac)(2))(2)(bpym)](0), with Me = nickel (II), manganese (II), zinc (II); hfacac = hexafluoroacetylacetonate, and bpym = bipyrimidine, adsorbed on Cu(100) surface. While Kondo features did not appear in the scanning tunneling spectroscopy spectra of nonmagnetic Zn-2, a zero bias resonance was resolved in magnetic Mn-2 and Ni-2 complexes. The case of Ni-2 is particularly interesting as the experiments indicate two adsorption geometries with very different properties. For Ni-2 complexes we have employed density functional theory to further elucidate the situation. Our simulations show that one geometry with relatively large Kondo temperatures T-K similar to 10 K can be attributed to distorted Ni-2 complexes, which are chemically bound to the surface via the bipyrimidine unit. The second geometrywe assign to molecular fragmentation: we suggest that the original binuclear molecule decomposes into two pieces, including Ni(hexafluoroacetylacetonate)2, when brought into contact with the Cu substrate. For both geometries our calculations support a picture of the (S = 1)-type Kondo effect emerging due to open 3d shells of the individual Ni2+ ions.

【 授权许可】

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