Download - Physics and Nanosciences

PhD School in Physical and Nanosciences
PhD Student: ERIK TANCINI
PhD
Physics 
Nanosciences 
Study Plan for the First Year
Attended internal Courses:
1) Fundamentals of magnetic recording (prof. Affronte)
2) Conduct and misconduct in science (prof. Ossicini)
Attended Seminars
I attended numerous seminars, including:
1) C. Lienau: "Watching the energy flow in solar cells and active plasmonic nanostrucutres on
ultrafast time scales" 15/03/2010
2) G. Maruccio: "Nanoscale spin-devices based on magnetic nanoparticles and molecules"
16/03/2010
3) A. Fasolino: "The structure of graphene: ripples, edges and folds" 19/03/2010
4) M. S. Hybertsen: "Exploring novel materials for photocatalytic water splitting" 28/06/2010
5) A. Morgante: "Surface corrugation, morphology and electronic structure of exfoliated graphene: a
LEEM, micro-LEED and micro-ARPES study" 09/07/2010
6) U. Hohenester: “Imaging particle plasmons using optical and electron microscopy” 30/11/2010
7) Kay Severin: "Novel ruthenium catalysts for atom transfer radical reactions" 03/12/2010
External courses and schools
I have so far followed the following schools and workshops:
ESMOLNA 2010: 3rd European School on Molecular Nanoscience, Miraflores de la Sierra, Madrid,
Spain, October 24-29, 2010;
MolSpinQIP: miniworkshop on Molecular Spin Clusters for Quantum Information Processing (annual
meeting), Modena, June 9, 2010
Publications:
1) E. Tancini, M-J. Rodriguez-Douton, L. Sorace, A-L. Barra, R. Sessoli, A. Cornia “Slow Magnetic
Relaxation from Hard-Axis Metal Ions in Tetranuclear Single-Molecule Magnets” Chemistry - A
European Journal, 2010, 16, 10482–10493.
2) M-J. Rodriguez-Douton, M.Mannini, L.Armelao, A-L. Barra, E. Tancini, R.Sessoli, A. Cornia
“One-step covalent grafting of Fe4 single-molecule magnet monolayers on gold”, Chem.
Commun., 2010, 47, 1467-1469
3) M. Mannini, E. Tancini, L. Sorace, P. Sainctavit, M-A. Arrio, Y. Qian, E. Otero, D. Chiappe, L.
Margheriti, J. Cezar, R. Sessoli, A. Cornia, “The Spin Structure of Surface-Supported SingleMolecule Magnets from Isomorphous Replacement and X-ray Magnetic Circular Dichroism”,
Inorganic Chemistry, 2011, accepted.
Participation to national and international conferences (poster, oral, invited)
1) ICMM 2010: The 12th International Conference on Molecule-Based Magnets, Beijing, China
October 8-12, 2010. “Easy-axis magnetic anisotropy from hard-axis metal ions in a tetranuclear
Single-Molecule Magnet” (poster)
2) ESMOLNA 2010: 3rd European School on Molecular Nanoscience, Miraflores de la Sierra,
Madrid, Spain, October 24-29, 2010. “Easy-axis magnetic anisotropy from hard-axis metal ions in
a tetranuclear SMM” (oral)
Tentative Title of your PhD: “Organizing Single-Molecule Magnets on surface by chemical tailoring”
Tutor: prof. Andrea Cornia
Report on the research activity of the first or second year
My PhD activity so far focused on the use of chemical tailoring as a way to engineer tetrairon(III) SingleMolecule Magnets (SMMs) to control their interaction with surfaces. The rational design of magnetic
molecules is of fundamental importance for the advent of molecular spintronics [1], which aims at
controlling the spin of molecular units using electric currents. Recent experiments on clusters derived
from [Fe4(OMe)6(dpm)6] (Fe4), (Hdpm = dipivaloylmethane) have demonstrated that Single-Molecule
Magnets (SMMs) can unquestionably be used as units in molecular devices, as their molecular magnetic
properties are retained on surface [2] and can be experimentally controlled by external stimuli [3]. We
focus on Fe4 complexes because they show several advantages over other SMMs, namely remarkable
electronic robustness and ease of functionalization. In particular, adsorption of Fe4 as monolayers on gold
can be achieved by site-specific substitution of the methoxy- groups with thioacetyl-terminated ligands
with formula AcS(CH2)nC(CH2OH)3, where Ac = acetyl. The length of the tethering unit can be
chemically adjusted in order to induce preferential ordering of the molecules at the surface level, although
the bulky magnetic core prevents effective intermolecular interactions. In fact, while for n = 9 the
monolayer is completely disordered, for n=5 the alkyl chain allows the magnetic axis to tilt up to an angle
of 35° with respect to the surface normal. Such a partially-oriented grafting affords anisotropic hysteresis
loops showing spectacular quantum steps [4]. We expect shorter spacers to further increase the degree of
ordering, allowing precise control over molecular orientation, as required for integration of SMMs into
devices.
I have so far focused on the synthesis of a series of new thioacetyl-terminated ligands with n down to 1.
Two ligands (C3SAc and C4SAc) have been successfully coordinated to Fe4 and the molecular structure
of the new substituted clusters has been elucidated by XRD on single crystals. After depositing and
characterizing the clusters as monolayers on Au by STM and XPS, I will participate to upcoming
synchrotron-based dichroism measurements that will allow a detailed study of the grafting geometry and
of the magnetic properties of the layers as functions of the spacer length.
Another important result I achieved is the isomorphous substitution of the central iron(III) of the Fe4 core
with a chromium(III) ion: magnetic characterization showed that this heterometallic cluster (Fe3Cr) is
indeed a SMM. Surface sensitive XAS/XMCD experiments on a thioacetyl-substituted derivative
deposited as monolayer on Au provided evidence that the antiferromagnetic nature of the interaction
between ions in tetrametallic SMMs is retained after deposition [5].
I also took part in the surface characterization of another functionalized Fe4 cluster featuring a 1,2dithiolan-3-yl- moiety as an anchoring group for gold substrates: XPS and XMCD measurements show
that this sulphur-based unit is covalently bonded to Au, providing another way to adsorb SMM on gold
without affecting the oxidation state of the metals and the core structure [6].
Finally we plan to use chemical tailoring to functionalize Fe4 with a couple of redox-active groups: the
idea is to oxidize selectively one of these groups to obtain a mixed-valence compound, where groups with
difference valence states could hopefully interact electronically with the magnetic core of the SMM. If an
“electron hopping” regime can be obtained by tuning the redox potential and spacer length, spectroscopic
methods may provide a valid alternative to devices to study transport properties through SMM.
[1] L. Bogani, W. Wernsdorfer, Nature Materials, 2008, 7, 179
[2] M. Mannini, et al. Nature Materials, 2009, 8, 194.
[3] A. Zyazin, et al. Nano Letters, 2010, 10, 3307.
[4] M. Mannini, et al. Nature, 2010, 468, 416.
[5] E. Tancini et al., Chem. Eur. J, 2010, 16, 10482.
[6] M. J. Rodriguez-Douton et al., Chem. Commun., 2011, 47, 1467.