team

Since 2015: Permanent position at CNRS (Chargé de Recherche)

2014 – 2015: Post-doctorat at the « Département Physique de la Matière et des Matériaux (P2M) » Institut Jean Lamour (IJL) and Université de Lorraine (Nancy).

2013 – 2014: Post-doctorat at the « Département Surfaces et Interfaces (DSI) » Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS).

2011 – 2013: Post-doctorat at the « Ultrafast phenomena in solids and at interfaces » AG Bovensiepen Duisburg-Essen Universität (Germany).

2007 – 2010: PhD Student at the group « Imagerie et Dynamique en magnétisme (IDMAG) » Laboratoire de Physique des Solides (LPS) (supervisor A. Mougin) and at the TEMPO beamline, Synchrotron Soleil (supervisor F. Sirotti).

Publications:

N. Bergeard, M. Hehn, S. Mangin, G. Lengaigne, F. Montaigne, M.L.M. Lalieu, B. Koopmans and G. Malinowski. « Hot-Electron-Induced Ultrafast Demagnetization in Co/Pt Multilayers ». Phys. Rev. Lett. 117, 147203 (2016)

M. El Hadri, P. Pirro, C.-H. Lambert, N. Bergeard, S. Petit-Watelot, M. Hehn, G. Malinowski, F. Montaigne, Y. Quessab, R. Medapalli, E. E. Fullertonand S. Mangin. « Electrical characterization of all-optical helicity-dependent switching in ferromagnetic Hall crosses ». Appl. Phys. Lett. 108, 092405 (2016)

J. Wieczorek, A. Eschenlohr, B. Weidtmann, M. Roesner, N. Bergeard, A. Tarasevitch, T. O. Wehling, U. Bovensiepen, « Separation of ultrafast spin currents and spin-flip scattering in Co/Cu(001) driven by femtosecond laser excitation employing the complex magneto-optical Kerr effect ». Phys. Rev. B, 92, 174410 (2015)

N. Bergeard, S. Schaffert, V. Lopez-Flores, N. Jaouen, J. Geilhufe, C. M. Gunther, M. Schneider, C. Graves, T. Wang, B. Wu, A. Scherz, C. Baumier, R. Delaunay, F. Fortuna, M. Tortarolo, B. Tudu, O. Krupin, M. P. Minitti, J. Robinson, W. F. Schlotter, J. J. Turner, Jan Luning, S. Eisebitt, and C. Boeglin, « Irreversible transformation of ferromagnetic ordered stripe domains in single-shot infrared-pump/resonant-x-ray-scattering-probe experiments. » Phys. Rev. B 91, 054416 (2015)

W. Baaziz, B. Pichon, Y. Liu, J.-M. Grenèche, C. Ulhaq-Bouillet, E. Terrier, N. Bergeard, V. Halté, C. Boeglin, F. Choueikani, M. Toumi, T. Mhiri, and S. Begin-Colin, « Tuning of Synthesis Conditions by Thermal Decomposition toward Core-Shell CoxFe1-xO@CoyFe3-yO4 and CoFe2O4 Nanoparticles with Spherical and Cubic Shapes« . Chemistry of Materials, pp 5063–5073; 08/2014, DOI: 10.1021/cm502269s

A. Eschenlohr, M. Sultan, A. Melnikov, N. Bergeard, J. Wieczorek, T. Kachel, C. Stamm, and U. Bovensiepen, « Role of spin-lattice coupling in the ultrafast demagnetization of Gd1-xTbx alloys ». Phys. Rev. B 89, 214423 (2014).

N. Bergeard, V. López-Flores, V. Halté, M. Hehn, C. Stamm, N. Pontius, E. Beaurepaire, and C. Boeglin, « Ultrafast angular momentum transfer in multisublattice ferrimagnets« . Nature Communications 5, 3466 (2014). (link to pub.).

INP : http://www.cnrs.fr/inp/spip.php?article2685

V. López-Flores, N. Bergeard, V. Halté, C. Stamm, N. Pontius, M. Hehn, E. Otero, E. Beaurepaire, and C. Boeglin, « Role of critical spin fluctuations in ultrafast demagnetization of transition-metal rare-earth alloys ». Phys. Rev. B 87, 214412 (2013)

N. Bergeard, J.-P. Jamet, A. Mougin, J. Ferré, J. Gierak, E. Bourhis et R.L. Stamps, « Dynamic fluctuations and 2D-melting at the spin reorientation transition » Phys. Rev. B 86, 094431 (2012)

J.-Y. Chauleau, B.J. McMorran, R. Belkhou, N. Bergeard, T.O. Mente¸ M.A Nino, A. Locatelli, J. Unguris, S. Rohart, J. Miltat, and A. Thiaville, « On the magnetization textures in NiPd nanostructures« . Phys. Rev. B 84, 094416 (2011)

N. Bergeard, M. Silly, D.Krizmancic, C. Chauvet, M. Guzzi, M. Izquierdo ,L. Stebel, P. Pittana, R.Sergo,G.Cautero, G. Dufour, F. Rochet and F. Sirotti, « Time resolved Photoelectron spectroscopy using synchrotron radiation time structure« . Journal of Synchrotron Radiation, vol 18, 245 (2011)

C. Chauvet, F. Polack, M. Silly, B. Lagarde, M. Thomasset, S. Kubsky, J–P.Duval, B. Pilette, I. Yao, N. Bergeard and F. Sirotti, « Carbon contamination of soft X-ray beamlines : dramatic antireflection coating effects observed in the 1keV photon energy region. » Journal of Synchrotron Radiation, 18, 761 (2011)

N. Bergeard, J-P. Jamet, J. Ferré, A. Mougin, B. Rodmacq, V. Baltz, J. Fassbender, « Spin reorientation transition and diagram in an He+ irradiated ultrathin Pt(3.5nm)/Co(0.5nm)/Pt(45nm) film« . J. Appl. Phys. 108, 103915 (2010)

Proceeding:

Eschenlohr, J. Wieczorek, J. Chen, B. Weidtmann, M. Rösner, N. Bergeard, A. Tarasevitch, T. O. Wehling, U. Bovensiepen, « Analyzing ultrafast laser-induced demagnetization in Co/Cu(001) via the depth sensitivity of the time-resolved transversal magneto-optical Kerr effect ». Ultrafast Phenomena and Nanophotonics XX, Proc. of SPIE Vol. 9746, 97461-E (2016)

Bergeard, V. López-Flores, V. Halté, E. Beaurepaire, C. Stamm, N. Pontius, M. Hehn, E. Otero, C. Boeglin, « Element- and Time-Resolved Dynamics in Rare-earth/Transition Metals Alloys » Springer Proceedings in Physics, Ultrafast Magnetism I, 159, 310 (2015)

F. Polack, M. Silly, C. Chauvet, B. Lagarde, N. Bergeard, M. Izquierdo, O. Chubar, D. Krizmancic, M. Ribbens, J-P. Duval, C. Basset, S. Kubsky, F. Sirotti, « TEMPO : A new insertion device beamline at SOLEIL for time resolved photoelectron spectroscopy experiments on solids and interfaces » AIP Conference Proceedings, 1234, 185 (2010)

Feautrier, P. and Le Coarer, E. and Espiau De Lamaestre, R. and Cavalier, P. and Maingault, L. and J-C Villégier and Frey, L. and Claudon, J. and Bergeard, N. and Tarkhov, M. and Poizat, J.-P. « High-speed superconducting single photon detectors for innovative astronomical applications » Journal of Physics : Conference Series, 97, 012087 (2008)

Book Chapter:

U. Bovensiepen, N. Bergeard Ultrafast Magnetization Dynamics Investigated With Femtosecond Time-Resolved X-ray Magnetic Circular Dichroism
In Magnetism and Synchrotron Radiation : Towards the Fourth Generation Light : Proceedings of the 6th International School “Synchrotron Radiation and Magnetism”, Mittelwihr (France), 2012
Series : Springer Proceedings in Physics, Vol. 151 (2013)

Invited speaker:

• N. Bergeard, V. López-Flores, V. Halté, E. Beaurepaire, C. Stamm, N. Pontius, M. Hehn, E. Otero, C. Boeglin
Element- and Time-Resolved Dynamics in Rare-earth/Transition Metals Alloys
Science at Femtoslicing facilities workshop, May 2013, (Synchrotron SOLEIL – St. Aubin, France)

Oral presentations:

N. Bergeard, G. Malinowski, M. Hehn, F. Montaigne, S. Mangin, « Hot-electrons transport as a driving force for sub-picosecond manipulation of magnetization ». 23ème congrès général de la société française de physique, Strasbourg (2015)

N. Bergeard, S. Schaffert, V. López-Flores, N. Jaouen, J. Geilhufe, C. M. Günther, M. Schneider, C. Graves, T. Wang, B. Wu, A. Scherz, C. Baumier, V. Cros, R. Delaunay, F. Fortuna, R. Mattana, M. Tortarolo, B. Tudu, G. Dakovski, O. Krupin, M. Patrick, W. F. Schlotter, J. J. Turner, J. Lüning, S. Eisebitt and C. Boeglin, « Ultrafast magnetic domain dynamics studied by magnetic resonant scattering at X-FEL sources ». 23ème congrès général de la société française de physique, Strasbourg (2015)

• N. Bergeard, V. López-Flores, V. Halté, E. Beaurepaire, C. Stamm, N. Pontius, M. Hehn, E. Otero, C. Boeglin
Element- and Time-Resolved Dynamics in Rare-earth/Transition Metals Alloys
Ultrafast Magnetism Conference, November 2013 – Strasbourg (France)

• N. Bergeard, V. López-Flores, V. Halté, E. Beaurepaire, C. Stamm, N. Pontius, M. Hehn, E. Otero, C. Boeglin
Element- and Time-Resolved Dynamics in Rare-earth/Transition Metals Alloys
8th International Conference on Fine Particle Magnetism, June 2013 – Perpignan (France)