Francesco Orsini – CV

Paolo Arosio – CV

Elena Garlatti - CV

Fatemeh Adelnia - CV





Congresses and publications

·      117 publications on national/international journals and about 100 participations at national and international congresses.

Scientific apparatuses

·        Spectrometers for Nuclear Magnetic Resonance (NMR) and Quadrupolar Resonance (NQR), for Muon Spin Resonance (mSR), for Electron Paramagnetic Resonance (EPR), for MR Imaging (Magnetic Resonance Imaging)

·        Adiabatic Calorimeter

·        SQUID (Superconducting Quantum Interference Device) for magnetic measurements

·        Mutual Inductance Bridge for AC susceptibility measurements

·        Apparatus for resisitivity measurements.

·        Superconducting magnets and electromagnets

·        Electronic and cryogenic apparatuses  (4He flux cryostat , 3He cryostat , dilution cryostat and so on).





a)      Magnetic Resonance Imaging on animal models for studying : (1) the blood perfusion and cerebral ischemia on rats; (2) the rheumatoid arthritis pathology;  (3) new contrast agents (characterization by magnetometry and relaxometry)

The Magnetic Resonance Imaging (MRI) technique is currently exploding due to its non-invasive character and continuosly increasing performances for clinical applications. A crucial role is played by Molecular Imaging, a term which refers to MRI used in conjuction with specific contrast agents able to reach specific molecule inside the tissues and to target them during (or hopefully before) a pathology evolution.

Our MRI activity concentrated on several research lines :

(a)    project, desing and development of coils for low-field Imagers (0.2 Tesla, E-SCAN, Esaote SpA), used for pathologies of ostheo-articular system (e.g. : acute inflammation (IA), rheumatoid arthritis (AR) );

(b)   optimization of sequences devoted to the study of AR and IA, in low-field systems (0.2 Tesla) and high-field systems (e.g. 7 Tesla, Pharmascan, Bruker SpA);

(c)    individuation iof a MRI protocol (e.g. T2 maps, dynamic MRI, etc.) to study the precursor effects and the evolution of AR, IA and, in near future, tumours;

(d)   analysis of the contrast agents (CA) effects on images for specific pathologies , in the framework of “targeted-MRI” projects (e.g. CA that tend to link to macrophages)

(e)    studies about MRI protocols able to better describe the devlopment and evolution of cerebral damages and to distinguish different kinds of damages, with and without CA; we are trying also to search for the better CA to study cerebral ischemia;

(f)     study of the nuclear spin-spin relaxation curves in terms of multiexponential components to access to the microscopic mechanisms responsible for the cerebral damages. 


b)      NMR-NQR and susceptibility measurements to study superconducting (SC) fluctuations and spin and charge-gap in  YBa2Cu3O7-d , YBa2Cu4O8, YBa2Cu3O7:Ca, La2-XSrXCuO4, MgB2, YNi2B2C, zero-dimensional SC nano-particles

This research field regards the study of superconducting fluctuations (SF) and of the precursor diamagnetism (PD) in conventional and high-Tc superconductors (HTSC), in forms of orientend powders, bulk or nano-particles. In general terms, by following the phenomenological theory of phase transitions Ginzburg-Landau (GL) the behaviour of the fluctuations of the order parameter y(r), linked to the number of Cooper pairs,  can be followed for T>Tc (Tc=transition temperature). For T>Tc the Cooper pairs are metastable and SF arise. Sf can give direct information on the mechanism of superconductivity and the role of eventual charge and spin “gap”, possibly opening for T>>Tc.

In BCS-like system, a special role is played by the recently discovered MgBs that presents a relatively high Tc~40K. For the first time we studied the magnetization curves M(H) at constant temperature T®Tc+ and experimentally was individuated a magnetic upturn field Hup , theoretically predicted, whose presence is due to the Cooper pairs breaking generated by the applied field itself.

In HTSC like i.e. YBa2Cu3O7-d , YBa2Cu3O7:Ca, La2-XSrXCuO4 , the effect of the magnetic field depends on the hole doping. In the case of optimally doping (maximum Tc) the M(H) curves for T®Tc+  can be explained in the framework of anisotropic GL theory. If the sample is “underdoped” or “overdoped”, for T>Tc mesoscopic regions (not chemically trivially disordered) with |y(r)|¹0 are formed ; the phase q(r) is site-dependent. This situation favours the formation of couples vortex-antivortex that induce an upturn field in  M(H) of different nature with respect to standard BCS SC. In the system YBa2Cu4O8 , this upturn field is never present and the data can be explained in terms of scaling laws and the Lawrence-Doniach functional. The existence of SF and their effect on the nuclear relaxation parameters (spin-spin and spin-lattice relaxation times) was confirmed by means of NMR-NQR measurements at different  applied fields. 

In the systems YNi2B2C and MgB2:Al , again an upturn field is displayed by M(H) but its origin resides in chemical disorder or distribution of Tc’s.

Finally , to verify the GL analytical solution in zero-dimension (diameter of SC particles d<x , x=coherence length) , preliminary experiments on Pb nanoparticles of different dimensions were performed. From M(H) and c(T) behaviour the theoretical predictions seem verified while the crossover toward the critical zone T~Tc+ will be studied. This study is possible in nano-particles because the extension of the critical zone is sizeable, differently from other SC systems.


c)      NMR, mSR, XMCD and susceptibility measurements on mesoscopic magnetic molecules, powders, films and single crystals, with properties similar to ferritin and on low-dimensional magnetic  clusters.

I have studied fundamental properties as spin dynamics, quantum tunneling of the magnetization (QTM) , topological spin structure, level crossing problem and basic magnetic interactions. The investigated systems are constituted by molecules containing a “core” of metallic ions (till 30) and magnetically isolated one each other by organic screens. This allows to study the properties of the single molecule (single molecule magnets, SMM, or molecular nanomagnets, MNM) with bulk quantitiy of sample. 

The most famous examples are high-spin molecules like Mn12 and Fe8, theoretically useful for magneti storage due to their bistability in the ground state.  In thse systems, an axial anisotropy (easy-axis z) due to the crystal field, determines a preferential direction of the magnetization M. The spin topology is complex and variable from one compound to the other; the excahbnge interactions are antiferromagnetic (AF), the dominant one being >100K . At low T, Mn12 and Fe8 are superparamagnetic with total ground state spin S=10 and an energy barrier (for M reorientation) ~ 60K and 27K, respectively. The energy levels has a double well with degenerate ±MS levels. By applying an external magnetic field, level crossings are induced for different Ms. For T<10K QTM is present. This process is thermally activated for T>1K (Mn12) and T>0.4K (Fe8) while is pure for the lowest T.

The low-dimensional nano-molecules (MNM) have spin topology of different kinds. We will give as example the magnetic rings. In these compounds the exchange interactions in the ground state (GS) are AF (total GS spin S=0). The spectrum of levels is discrete and follows approximately the Lande’s rule, the lowest energy gap being of the order of some tenths of K. Even here level crossings can be induced. For low temperatures , some anisotropic parts of the Hamiltonian (anisotropic exchange, Dzyaloshinki-Moriya interaction, etc.) determines the main physical properties.

By NMR-NQR , susceptibility and mSR measurements, we studied the spin dynamics of all the above systems in the different temperature regions. Novel information on microscopic parameters (like energy levels broadening, spin-phonon interaction, QTM paths, local spin  arrangement, level crossing properties, etc.) were obtained.  


d)      Magnetic measurements on molecular 1-D magnetic chains containing rare earth ions (Gd,Eu) or metals (Co) alternated to radicals (Et,iPr,Ph,Me ; PhOMe) for the study of peculiar phase transitions and/or slow-relaxation of magnetization (nano-wires)

In the rare-earth chains, the molecular magnetic 1D system  is formed by Gd(3+) s=7/2 spins alternating to radicals R s=1/2. The intrachain interactions are AF and the system is frustrated by the presence of competing nearest-neighbour (Gd-R) and next-nearest-neighbour (Gd-Gd and R-R) interactions. The interchain interaction is negligible (Jinter ~ 10-4 Jintra). As a final result one has a XY system that at low T presents an effective spin Seff arrange in a helicoidal scheme. In these systems the Villain’s conjecture was verified, thus demonstrating that at high T the system is paramagnetic, at intermdiate T has a transition to a chiral phase and at low T a transition to a 3D ordered helicoidal system.

Particularly, by the use of mSR measurements coupled to specific heat, one has observed the absence of an anomaly in the 2-spin correlation function in Gd-iPr compound at T~2K, where a transition to a chiral phase was suggested.

In the transition metal based chains,  the system is constituted by Co(II) (S=1/2 for T<80K) ions alternated to radicals (s=1/2); the chains are not interacting (Jinter ~ 10-4 Jintra). The g-factor of the Co(II) ion is ~7.4 while the one of radical is ~2; in this way a ferrimagneti chain is obtained with just one effective intrachain AF exchange interaction (Jintra~200K). The peculiarity of these systems is that at low The magnetization M relaxes slowly (nanowires) and they can be suggested as bistable units for memory storage. The relaxation time of M follow an Arrhenius law t=t0 exp(D/T),  with a barrier ~150K.

With NMR and mSR measurements we determined the existence of a second kind of relaxation mechanism, not detected by macroscopic techniques. 


e)      mSR and susceptibility measurements on high-Tc superconductors, Nd1.85Ce0.15CuO4+d

For many years, the magnetic phase diagram of high-Tc superconductors (HTSC) was debated as a fundamental step toward the comprehension of the superconducting micrioscpic mechanism and the understanding of the role of the elementary magnetic excitations. In the system La2-xSrxCuO4+d, studied by means of NMR-NQR, mSR and susceptibility, for very low doping (x<0.02) the system at low T (T<20K) has a transition to a spin-glass (SG) phase; for intermediate doping (0.02<x<0.08) cluster-SG phase is formed while for x>0.08 the transition to the supeconducting phase is verified , with a maximum Tc~35K. In the region 0.08<x<0.12, a possible coexistence of magnetism and superconductivity (classically forbidden) was inferred and partly demonstrated.

The described phase  diagram was shown to be “universal” for all hole-doped HTSC and we confirmed it also in electron-doped HTSC like Nd2-xCexCuO4+d  by means of mSR and susceptibility measurements. This superconductor has a maximum Tc~25K and can vary its phase with proper oxygen doping at fixed content of Ce (x=0.15).  The result is a third line in the phase diagram, in correspondence of Ce doping =0.15, that confirms the existence of a SG phase for oxygen content d>0.06.


f)       Characterization of magnetic nanoparticles for MRI and other functionalities

Recently the scientific community paid a lot of attention to the synthesis of multifunctional magnetic nanoparticles with the aim of obtaining compounds with different applications in the field of bio-physics. Among these applications the possibilities to obtain new contrast agents for Magnetic Resonance Imaging (MRI) and to reveal (with magnetic techniques) the success of the local application of a “pathology specific drug” via the use of a delivering molecule (drug delivery), were evidenced. The success of these applications could help in prevention and care of diseases. The research activity is focused on the characterization of newly synthesized magnetic nanoparticles/nanomagnets to be used possibly as MRI contrast agents, by means of Nuclear Magnetic Resonance (NMR) and Atomic/Magnetic Force Microscopy (AFM/MFM), but also useful for magnetic hyperthermia. Possible functionalization with fluorophores are also investigated. By AFM/MFM, the morphological and (surface) magnetic structure of new compounds are studied. By NMR the relaxivity curves of new nanosize magnetic materials are investigated, after preliminary magnetic susceptibility and magnetization measurements. The structural and morphological properties of novel systems are put in connection with their physico-chemical properties.





·      Institute of Pharmacological Sciences - Universita’ di Milano – Prof. M.Asdente, Prof.E.Tremoli, Dr.U.Guerrini and Dr.G.Sironi

·      Dipartimento di Chimica, Universita’ di Torino-Italy, prof. S. Aime

·      Bracco SpA, Milano (Italy)

·      Esaote SpA, Genova (Italy)

·      Dipartimento di Chimica, Universita' di Firenze-Italy, prof. D.Gatteschi

·      Dipartimento di Chimica Fisica, Universita’ di Pavia-Italy, prof. Flor

·      Dipartimento di Fisica di Firenze-Italy, prof.A.Rettori

·      Dipartimento di Fisica di Genova-Italy, prof.U.Valbusa

·      CNRS-LCMI, Grenoble (France), prof.C.Berthier and Dr.M.Horvatic

·      IEQ – CNR (Quantum Electronics Institute), Firenze-Italy, dr.M.G.Pini and dr.U.Balucani

·      Chemistry department, Universita’  di Modena-Italy, prof.A.Fabretti and Dr. A. Cornia

·      Dept.of Physics, Ames Lab, Iowa State University, Ames-Iowa (USA), prof.F.Borsa

·      Dept. of Physics, Hokkaido University, Japan, Prof.Kumagai, Dr. Y. Furukawa

·      Dept. Of Chemistry, Tallahassee (FloridaUSA), prof. Dalal

·      (OLD: Dept. Of Physics, Kyoto Unversity, Japan, Prof. T.Goto)

·      (OLD: Superior Physics Department (Engineering faculty), Universita’ di Firenze-Italy, prof.Spina)

·      (OLD : IROE – CNR (Institute for Electromagnetic Waves),  Firenze-Italy, dr.Cianchi)

·      Dipartimento di Fisica, Universita’ di Modena-Italy , prof. M. Affronte

·      Dipartimento di Fisica, Universita’ di Torino-Italy, prof. C. Guiot

·      Dipartimento di Fisica, Universita’ di Parma-Italy, Dr. L. Romano’

·      INFM-Roma Unit, Italy, prof. A. Varlamov

·      Dept. of Phys., Univ. of Sofia, Bulgaria, Prof. T. Mishonov

·      CNRS, High-Field Magnetic Laboratory, Grenoble (France) prof. C. Berthier, Dr. M. Horvatic, Dr. M.H. Julien

·      Laboratoire Louis Neel-CNRS, Grenoble (France), prof. B. Barbara

·      Dept. Chemistry, Manchester University (UK), prof. R. Winpenny

·      Dept. Chemistry, Karlsruhe University (Germany), prof. A. Powell