POSTER PRESENTATIONS - NNPDF



POSTER PRESENTATIONS

ABSTRACT

ITALIAN SCHOOL ON MAGNETISM

Milano

18-22 Aprile 2016

Tm3+-X3+ dinuclear complexes (X = Fe, Co) behave as molecular magnets: Magnetic dynamics in comparison with Dy3+-Co3+ system

Asma Amjad,1 Albert Figuerola,2 and Lorenzo Sorace,1

1INSTM Research Unit – LAMM Dipartimento di Chimica "U. Schiff", Università di Firenze, Sesto Fiorentino, FI, Italy

2Universitat de Barcelona, Barcelona, Spain

asma.amjad@unifi.it

A favored approach to probing the nature and magnitude of anisotropy of the lanthanide and the exchange interaction between the lanthanide and the 3d-metal is the diamagnetic substitution approach [1]. The present study focuses on the dynamical behavior of Tm3+ in [1] with paramagnetic Fe3+ and diamagnetic Co3+ ion, as until recently almost no evidence of slow relaxation of magnetism existed for Tm3+ [2]. We show proof of slow relaxation of magnetization observed in both the Tm derivatives, where the extracted relaxation time τ vs. T-1 behavior is then modeled with different relaxation processes. Quite interestingly, in addition to the above process, a secondary peak in the out-of-phase susceptibility signal is also observed in the Tm-Co complex. This additional feature is field dependent and is attributed to the intermolecular interactions as opposed to the single molecule behavior portrayed by the earlier peak. The behavior of the Tm derivatives is further investigated in comparison with the iso-structural Dy-Co complex.

[1] L. Sorace, C. Sangregorio, A. Figuerola, C. Benelli, , D. Gatteschi, Chem. Eur. J. 15 (2009) 1377

[2] Y. Meng, Y. Qiao, Z. Yi-Quan, S. Jiang, Z. Meng, B. Wang, Z. Wang, S. Gao, Chem. Eur. J. 22 (2016) 4704

Surface-Orientation-Dependent Spin Quenching of Adsorbed Co Porphyrin Molecules

Lucas M. Arruda1, Matthias Bernien1, Fabian Nickel1, Nino Hatter1, Lalminthang Kipgen1, Christian F. Hermanns1, Jorge Miguel1, Alex Krüger1, Dennis Krüger1, Timo Bißwanger1, Jens Kopprasch1, Qingyu Xu1,2, and Wolfgang Kuch1

1Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin

2Department of Physics, Southeast University, 211189 Nanjing

l.arruda@physik.fu-berlin.de

Metalloporphyrin molecules on surfaces have been attracting the attention of the scientific community because their central metal ion is fourfold coordinated within the molecular plane and displays two empty coordination sites that can be occupied by additional ligands or a surface. We have investigated submonolayers of Co octaethyl porphyrin molecules on Cu(001) and Cu(111) as well as on Au(001) and Au(111) surfaces by means of x-ray absorption spectroscopy and x-ray magnetic circular dichroism in an external magnetic field of 6 T at a temperature of 5 K. We find the Co magnetic moment quenched when the molecule is adsorbed on Cu(111), Au(001), and Au(111). On Cu(001), on the contrary, the Co ions display a significant magnetic moment. We attribute this modification of the molecular magnetic properties to the formation of a hybrid electronic state at the metal-organic interface. — Financial support by project VEKMAG (BMBF 05K13KEA) and CAPES is gratefully acknowledged.

The annealing effect of the amorphous ferromagnetic ribbons

on the magnetoelectric effect in composite multiferroics

I.Baraban1, F.Fedulov2, L.Fetisov2, K.Chichay1, V.Rodionova1

1Immanuel Kant Baltic Federal University, 236041 Kaliningrad, Russia

2 Moscow Technological University, 119454, Moscow, Russia

Presenter’s e-mail address: irinmachay@

Currently, much attention is given to the creation of the magnetic field sensors and the autonomous energy sources on the base of the magneto-electric (ME) effect [1]. The most important tasks are improving of the ME interaction efficiency and increasing of the operating temperature range of the structure. One of the ways is to change the manufacturing technology to prepare the ME-elements (layered structures of ferromagnetic-piezoelectric). Usually layered structures are made by bonding of the layers using an epoxy adhesive. However, the value of the ME effect in bonded structures falls, in particular, because of the process of softness of the adhesive at high temperatures. Magnetic and elastic properties of the layers of the structure also change [2]. It is possible to improve the ME characteristics of structures significantly by connecting of the layers using high-temperature soldering. Therefore the effect of high temperature annealing of ferromagnetic ribbons (25 µm thickness, Magnetic Alloy 2605S3A by Metglas) on their magnetic properties studied in this work. We also investigated the MEE in two-layered structures comprising annealed ferromagnetic layer and PZT (0.3 mm thickness).

[1] D.A. Burdin, et al. Technical Physics Vol. 59, No. 9 (2014) 1350–1355

[2] D.A. Burdin, et al. JMMM Vol. 358–359, (2014), 98–104

Magnetoplasmonic crystal as a magnetic field sensor

V. Belyaev1, A.Grunin2, A.Fedyanin2, V.Rodionova1

1Immanuel Kant Baltic Federal University, 236041 Kaliningrad, Russia

2 Lomonosov Moscow State University, 119991, Moscow, Russia

Presenter’s e-mail address: v.k.belyaev@

Surface Plasmon Resonance (SPR) sensors are widely used for different applications [1] and the main task in this sphere is increasing of their sensitivity. One of the ways – add one more type of modulation, for example, by magnetic field. Typical SPR sensors consist of noble metal/dielectric material pair and appreciable modulation can be reached in magnetic fields up to several Tesla. The other way is using magneto-optical (MO) effects. It is possible to combine both of these ways by using the magnetoplasmonic crystals (MPlCs) – multilayer structures fabricated of noble and ferromagnetic layers on substrate with certain spatial profile [2-3]. This way can demonstrate that it is possible both to enhance the MO activity of the system by surface plasmon excitation, and to modulate the surface plasmon properties by applying of the external magnetic field [4]. The results of investigation of magnetic, optical, magneto-optical properties and a possibility of fabrication of a magnetic field sensor prototype based on MPlCs will be shown.

[1] Wong C. L., Olivo M.., Plasmonics., Volume 9, Issue 4 , pp 809-824, (2014)

[2] Grunin A., Zhdanov. A., Fedyanin A., Appl. Phys. Lett. 97, 261908, (2010)

[3] Belotelov V., Akimov. I, Bayer M., Nat. Nanotechnol 6, 370, (2011)

[4] Belyaev V., Grunin A., Fedyanin A., Rodionova V, SSP, Vols 233-234, pp. 599-602, (2015)

Magnetic properties of ultra-thin Cr layers on Fe(100)-p(1x1)O

G. Berti1, A. Brambilla1, A. Calloni1, A. Picone1, M. Riva1,2, G. Bussetti1, M. Finazzi1, L. Duò1, F. Ciccacci1

1Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano, Italy

2Current address: Institute of Applied Physics, TU-Wien, Wiedner Hauptstraße 8-10, 1040 Vienna, Austria

Presenter’s e-mail address: giulia.berti@polimi.it

The Cr/Fe system is one of the most studied AF/F heterostructure because of its model character and its importance for the GMR effect and in spintronic devices. Its magnetic properties can be affected by the interplay of several parameters, such as interface mixing, strain and defects. If the growth of ultra-thin layers is performed on substrates kept at high temperature, chemical mixing prevents the formation of a well-defined interface, while low-temperature deposition leads to three-dimensional growth, both issues being detrimental for the study of ultra-thin Cr films. We found that a sharp Cr/Fe interface can be obtained even at high deposition temperatures by depositing Cr on the oxygen passivated Fe-p(1x1)O substrate: oxygen floats on the growing film acting as a surfactant and promoting a layer-by-layer growth, so for sub-monolayer coverages a Cr oxide is formed. For thicker films, the Cr oxide layer is confined at the surface. We investigate the coupling between the Fe substrate and the Cr overlayer, and demonstrate the effectiveness of our growth recipe in promoting the formation of a layer-wise AF structure in the Cr film, starting right from the interface. The magnetic characterization is performed by means of XMCD [1], and SP-PES [2].

[1] A. Brambilla, G. Berti, et al., J. Appl. Phys. 114 (2013) 123905

[2] G. Berti et al., Appl. Phys. Lett. 106 (2015) 162408

Photostructurable sol-gel material doped with magnetic nanoparticles for magneto-optical properties

C. Bidaud1*, E. Gamet2, F. Royer2, S. Neveu3, D. Berling1, O. Soppera1

1Institut de Science des Matériaux de Mulhouse (IS2M), CNRS-UMR 7361, 15 rue Jean Starcky, Mulhouse, France

2 Laboratoire Hubert Curien (LaHC), CNRS-UMR 5516, 18 rue du Professeur Benoît Lauras, Saint Etienne, France

3 Laboratoire PHENIX, CNRS-UMR 8234, Université Pierre et Marie Curie, 4 place Jussieu, Paris, France

*clementine.bidaud@uha.fr

Non-reciprocal magneto-optical (MO) devices are essential components and of high interest and challenging for the development of innovative integrated devices in telecommunication technologies or sensing applications. However, actual MO materials require multi-steps processes at high temperature which impedes a direct integration as optical components in complex systems.

We developed a MO material, based on a sol-gel matrix doped with magnetic nanoparticles (MNP). Moreover, through direct laser writing this matrix can be nanostructured [1, 2]. Thanks to their excellent optical and mechanical properties, those thin films turn out to be excellent candidates for incorporation of MNP, and to be used as a MO qualified material [3].

The main challenge of this composite approach lies in the incorporation of crystalized MNP in the photostructurable host matrix in a randomly dispersed regime of individual nanoparticles and avoiding any NPM aggregation.

The composite is finally structured at a sub-micrometer scale with simple laser-writing process, without any post-annealing. Magneto-optical properties (Faraday and Kerr effects) have also been evaluated and clearly demonstrate potential applications of our MO material.

[1] F. Stehlin, et al., J. Mater. Chem. 2 (2014) 277-285.

[2] H.C. Lin, et al., Scientific Reports. 5 (2015).

[3] H. Amata, et al., Appl. Phys. Lett. 99 (2011).

Coupling molecular spin centers to microwave resonators: towards integration of molecular qubits in quantum circuits

ITALIAN SCHOOL ON MAGNETISM 2016 abstract

Claudio Bonizzoni1,2, Alberto Ghirri2 and Marco Affronte1,2

1Dipartimento FIM, Università di Modena e Reggio Emilia, via G. Campi 213/A, 41125, Modena, Italy

2Istituto Nanoscienze CNR Nano S3, via G. Campi 213/A, 41125, Modena, Italy

claudio.bonizzoni@unimore.it

In the last years, great attention has been devoted to the study of the coupling between spins and microwave photons trapped in a cavity. In the strong coupling regime, the collective system is described by the Tavis-Cummings Hamiltonian, and the coherent transfer of information between spins and photons can be achieved. Thanks to their coherent spin dynamics and tailorable magnetic properties, molecular spin systems are retained promising candidates for quantum technologies.

We report a detailed study of the magnetic coupling between a high Tc YBCO/sapphire coplanar resonator [1] and different ensembles of single-ion molecular nanomagnets, namely PPh4Cu(mnt)2 (where mnt = maleonitriledithiolate), Dy-trensal (trensal=tris[2-(salicylideneamino)ethyl] amine) and ErPc2-[TBA]+ (with TBA+ = tetra-n-butylammonium cation). The coupling strengths and the linewidths are studied for different dilutions and orientations, and the results are compared with organic radicals [2] and other spin ensembles from the literature. We discuss possible strategies to improve the coupling strength and the possibility to reach the strong coupling regime at finite temperature.

[1] A. Ghirri, C. Bonizzoni et al. Appl. Phys. Lett. 106 (2015) 184101

[2] A. Ghirri, C. Bonizzoni et al. submitted.

Animal model study of magnetic nanoparticles biodistribution by AC susceptibility

Marko Boskovic1, Marija Perovic1, Sanja Vranjes-Djuric1, Vladan Kusigerski, Bratislav Antic, Vojislav Spasojevic

1Institute of Nuclear Sciences Vinca, University of Belgrade, Belgrade, Serbia

markob@vinca.rs

All materials intended for in vivo applications must pass number of specific tests, from biocompatibility and toxicity in vitro tests to biodistribution and pharmacokinetic in vivo studies on animals. Biodistribution results answer some very important questions: How long does injected material stay in blood circulation? What are the accumulation sites? How do external parameters, such as external magnetic field, influence behavior of your material? Various protocols for measuring biodistribution of different materials are commonly used. This paper presents one of alternative methods convenient for determination of biodistribution of magnetic nanoparticles [1-3]. The method is based on AC susceptibility measurements of animal tissues in question and uses the fact that paramagnetic and diamagnetic species naturally present in organism do not contribute to the imaginary part of susceptibility.

[1] Lázaro, F. J. et al. J. Magn. Magn. Mater. 311 (2007) 460

[2] López, A., Gutiérrez, L. & Lázaro, F. J. Phys. Med. Biol. 52 (2007) 5043

[3] Gutiérrez, L. et al. J. Phys. D. Appl. Phys. 44 (2011) 255002

MAGNETOFLUORESCENT NANOCARRIERS FOR BIOIMAGING

AND DRUG DELIVERY

Joanna Boucard1, Christophe Blanquart2, Camille Linot2, Lénaïc Lartigue1, Eléna Ishow1

1CEISAM Laboratory, University of Nantes, 44322 Nantes, France

2Health Research Institute, University of Nantes, 44322 Nantes, France

joanna.boucard@univ-nantes.fr

We have developed a family of fluorescent organic nanospheres (FONs) (hydrodynamic diameter ~100 nm) by reprecipitating hydrophobic organic fluorophores in water. Their emission can be tuned as a function of the charge transfer magnitude involved in the excited state, hence fluorescence over the 610 to 675nm spectral range can be obtained. The introduction of bulky tert-butyl group avoids π−π intermolecular aggregation, usually leading to dramatic decrease in fluorescence in the solid state. Compared to free dyes in solution, FONs provide a higher emission contrast thanks to a high load of active units (105 fluorophores per assembly) [1].

[pic]

Figure 1. Structures of FON-forming fluorophores fpOH, fthia-CN-pOH and fthia-pOH

The extended charge transfer structure, ensuring red to NIR emission and a large Stokes shift, is completed with phosphonic acid moieties that bring colloidal stability upon partial ionization in water. Such moieties are moreover amenable to chelate iron oxide superparamagnetic nanoparticles, regarded as attractive contrast agents for in vivo MRI. [2] First attempts were successfully conducted with 7 nm-large iron oxide nanoparticles. Currently, 10 nm-large maghemite nanoparticles are expected to yield even more contrast imaging.

Preliminary tests show efficient drug encapsulation inside the FON structure. Furthermore, after appropriate coating with pegylated polyelectrolyte, preferential accumulation of the resulting nanoassemblies was found in mice tumors. All these combined properties pave the way toward theranostic potentialities.

[1] A. Faucon et al. Adv. Health. Mater. 4 (2015) 2727

[2] A. Faucon et al. J. Mater. Chem. C. 1 (2013) 3879

MR hyperpolarization of metabolites by means of parahydrogen

and magnetic field cycle

Eleonora Cavallari1, Francesca Reineri1, Carla Carrera, Silvio Aime

1Departement of Molecular Biotechnology and Health Sciences, University of Torino,

Via Nizza 52, 10126, Torino, Italy

eleonora.cavallari@unito.it

It was recently shown that hyperpolarized [1-13C]-metabolites (e.g. [1-13C]-pyruvate) can be obtained using the ParaHydrogen Induced Polarization by means of Side Arm Hydrogenation (PHIP-SAH) method.1 

This method relies on 1) hydrogenation of the unsaturated side-arm of the ester derivative of the target metabolite, 2) polarization transfer from the parahydrogen protons to the 13C carboxylate signal, 3) cleavage of the ester by means of hydrolysis.

We show, both experimentally and theoretically, that efficient polarization transfer to the 13C carboxylate signal can be obtained by means of magnetic field cycling (MFC).2 This method relies on two asymmetric passages from earth’s magnetic field (50uT) to almost zero field ( ................
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