6 research outputs found
Spin tuning of electron-doped metal-phthalocyanine layers
The spin state of organic-based magnets at interfaces is to a great extent determined by the organic environment and the nature of the spin-carrying metal center, which is further subject to modifications by the adsorbate-substrate coupling. Direct chemical doping offers an additional route for tailoring the electronic and magnetic characteristics of molecular magnets. Here we present a systematic investigation of the effects of alkali metal doping on the charge state and crystal field of 3d metal ions in Cu, Ni, Fe, and Mn phthalocyanine (Pc) monolayers adsorbed on Ag. Combined X-ray absorption spectroscopy and ligand field multiplet calculations show that Cu(II), Ni(II), and Fe(II) ions reduce to Cu(I), Ni(I), and Fe(I) upon alkali metal adsorption, whereas Mn maintains its formal oxidation state. The strength of the crystal field at the Ni, Fe, and Mn sites is strongly reduced upon doping. The combined effect of these changes is that the magnetic moment of high- and low-spin ions such as Cu and Ni can be entirely turned off or on, respectively, whereas the magnetic configuration of MnPc can be changed from intermediate (3/2) to high (5/2) spin. In the case of FePc a 10-fold increase of the orbital magnetic moment accompanies charge transfer and a transition to a high-spin state
Interface physics of perovskite manganese oxides: A polarized x-ray spectroscopy and scattering study.
Interface physics of perovskite manganese oxides: A polarized x-ray spectroscopy and scattering study
Spin tuning of electron-doped metal-phthalocyanine layers
The spin state of organic-based magnets at interfaces is to a great extent determined by the organic environment and the nature of the spin-carrying metal center, which is further subject to modifications by the adsorbate-substrate coupling. Direct chemical doping offers an additional route for tailoring the electronic and magnetic characteristics of molecular magnets. Here we present a systematic investigation of the effects of alkali metal doping on the charge state and crystal field of 3d metal ions in Cu, Ni, Fe, and Mn phthalocyanine (Pc) monolayers adsorbed on Ag. Combined X-ray absorption spectroscopy and ligand field multiplet calculations show that Cu(II), Ni(II), and Fe(II) ions reduce to Cu(I), Ni(I), and Fe(I) upon alkali metal adsorption, whereas Mn maintains its formal oxidation state. The strength of the crystal field at the Ni, Fe, and Mn sites is strongly reduced upon doping. The combined effect of these changes is that the magnetic moment of high- and low-spin ions such as Cu and Ni can be entirely turned off or on, respectively, whereas the magnetic configuration of MnPc can be changed from intermediate (3/2) to high (5/2) spin. In the case of FePc a 10-fold increase of the orbital magnetic moment accompanies charge transfer and a transition to a high-spin state
Spin Tuning of Electron-Doped Metal–Phthalocyanine Layers
The spin state of organic-based magnets
at interfaces is to a great
extent determined by the organic environment and the nature of the
spin-carrying metal center, which is further subject to modifications
by the adsorbate–substrate coupling. Direct chemical doping
offers an additional route for tailoring the electronic and magnetic
characteristics of molecular magnets. Here we present a systematic
investigation of the effects of alkali metal doping on the charge
state and crystal field of 3d metal ions in Cu, Ni, Fe, and Mn phthalocyanine
(Pc) monolayers adsorbed on Ag. Combined X-ray absorption spectroscopy
and ligand field multiplet calculations show that Cu(II), Ni(II),
and Fe(II) ions reduce to Cu(I), Ni(I), and Fe(I) upon alkali metal
adsorption, whereas Mn maintains its formal oxidation state. The strength
of the crystal field at the Ni, Fe, and Mn sites is strongly reduced
upon doping. The combined effect of these changes is that the magnetic
moment of high- and low-spin ions such as Cu and Ni can be entirely
turned off or on, respectively, whereas the magnetic configuration
of MnPc can be changed from intermediate (3/2) to high (5/2) spin. In the case of FePc a 10-fold increase of the
orbital magnetic moment accompanies charge transfer and a transition
to a high-spin state
Spin Tuning of Electron-Doped Metal–Phthalocyanine Layers
The spin state of organic-based magnets at interfaces is to a great extent determined by the organic environment and the nature of the spin-carrying metal center, which is further subject to modifications by the adsorbate-substrate coupling. Direct chemical doping offers an additional route for tailoring the electronic and magnetic characteristics of molecular magnets. Here we present a systematic investigation of the effects of alkali metal doping on the charge state and crystal field of 3d metal ions in Cu, Ni, Fe, and Mn phthalocyanine (Pc) monolayers adsorbed on Ag. Combined X-ray absorption spectroscopy and ligand field multiplet calculations show that Cu(II), Ni(II), and Fe(II) ions reduce to Cu(I), Ni(I), and Fe(I) upon alkali metal adsorption, whereas Mn maintains its formal oxidation state. The strength of the crystal field at the Ni, Fe, and Mn sites is strongly reduced upon doping. The combined effect of these changes is that the magnetic moment of high- and low-spin ions such as Cu and Ni can be entirely turned off or on, respectively, whereas the magnetic configuration of MnPc can be changed from intermediate (3/2) to high (5/2) spin. In the case of FePc a 10-fold increase of the orbital magnetic moment accompanies charge transfer and a transition to a high-spin state