Maria Iavarone

Physicist

Materials Science Division; Bldg. 223 Argonne National Laboratory 9700 South Cass Avenue Argonne, Illinois 60439 phone: 630-252-9012 fax: 630-252-7777 email: maria@anl.gov

Visit my SPM research lab

Education:

• Ph.D., Solid State Physics, University of Napoli "Federico II", Napoli, Italy, 1995
• M.S., B.S., Physics, University of Napoli "Federico II", Napoli, Italy, 1992

• Physicist, Argonne National Laboratory, 2005
• Assistant Scientist, Argonne National Laboratory, 2001
• INFM Researcher, Department of Engineering, University of Napoli, 2000
• Maria Goeppert-Mayer Distinguished Scholar, Argonne National Lab, 2000
• INFM Researcher, Department of Engineering, University of Napoli, 1998
• INFM Post-doctoral Fellow (Napoli) & Visiting Scholar (Argonne), 1997
• Visiting Scolar, Materials Science Division, Argonne National Lab, 1996

• ISI recognition as lead author of most cited publication in the field of Superconductivity, 2001
• Maria Goeppert-Mayer Distinguished Scholar Award, 1999
• INFM (National Institute for Physics of Matter - Italy) Fellowship Award, 1996 and 1998
• CNR Visiting Scholar Award, 1998

• Visiting Associate Professor at the International Frontier Center for Advanced Materials (IFCAM), Institute for Materials Research, Tohoku University, Japan, 2008
• Lecturer of "Scanning Probe Microscopy" for the Ph.D. in "Advanced Technologies", University of Napoli "Federico II", 2004-present
• Professor of Physics for Computer Engineering at University of Napoli "Federico II", Faculty of Engineering, 2000-2001
• Professor (under contract Art. 25 of the University of Napoli "Federico II", Faculty of Engineering) for "Structure of the Matter", 1998-1999

• Member of the American Physical Society
• Member of the Italian National Institute for Physics of Matter (INFM)
• DOE - SBIR Program Review Panelist
• Member of Argonne's Young Scientist Carreer Committee

• Scanning Tunneling Microscopy and Spectroscopy in MgB₂

The salient feature in MgB₂ is the existence of two distinct gaps on two different portions of the Fermi surface. The two sets of electrons are only weakly interacting and the high-T_c of 40K is due to a strong coupling between a small fraction of phonons and a fraction of the Fermi surface. The directional nature of tunneling has been used to selectively probe the two different type of bands in this material and to measure the two superconducting gaps in thin films, in single crystals, and in samples with various amount of disorder.
Using a combination of scanning tunneling microscopy and spectroscopy we have shown two distinct energy gaps at 2.3 meV and 7.1 meV. Our experimental observations are consistent with the existence of two-band superconductivity in the presence of interband superconducting pair interaction and quasiparticle scattering. Temperature evolution of the tunneling spectra follows the BCS scenario with both gaps vanishing at the bulk T_c. This has been first direct confirmation of the importance of Fermi-surface sheet dependent superconductivity in MgB₂.

• Molecular Electronics

Molecular electronics involves the single or small set of molecules that can perform fundamental electronic functions such as wires, diodes, switches, gain elements, etc. It is a rapidly growing area of materials science involving highly interdisciplinary research teams. Since basic electronic functions in these future devices are performed on a molecular level, scanning tunneling spectroscopy is an ideal tool for characterizing the electronic properties of these molecules. We focus our studies on systems showing rectifying behavior as well as photosynthetic systems.

• Mesoscopic Superconductors

In mesoscopic materials the free energy of the surface is comparable to or dominates the energy of the bulk, producing a rich variety of new equilibrium states which vary continuously with the surface to volume ratio. Abrikosov vortices in bulk superconductors form a hexagonal lattice, while in mesoscopic structures they form various finite patterns that minimize the surface energy as well as their mutual repulsion. Recent theoretical calculations predict an orderly shell structure for the vortices, similar to the shell structure of electrons in atoms. Scanning tunneling microscopy (STM) is an ideal tool for imaging of superconducting order parameter in submicron samples. Spectroscopic STM scans provide unprecedented resolution in imaging of the Abrikosov vortices. Novel vortex structures such as vortex shells, giant vortex state, and multiquanta vortices should exist only due to mesoscopic size of the sample. Focus of our study is to examine these vortex phases using STM. The work could have significant impact on both basic science and applicability problems of tiny superconductors.

• Effect of Magnetic Impurities on the Vortex Lattice Properties in NbSe₂ Single Crystals, M. Iavarone, R. Di Capua, G. Karapetrov, A.E. Koshelev, D. Rosenmann, H. Claus, C.D. Malliakas, M.G. Kanatzidis, T. Nishizaki, N. Kobayashi, accepted in Physical Review B (2008)
• Tunable Transport in Magnetically Coupled MoGe/Permalloy Hybrids, A. Belkin, V. Novosad, M. Iavarone, J. Fedor, J. Pearson, A. Petrean-Troncalli, G. Karapetrov, Applied Physics Letters 93, 072510 (2008)
• Superconductor - Ferromagnet Bilayers: Influence of Magnetic Domain Structure on Vortex Dynamics, A. Belkin, V. Novosad, M. Iavarone, J. Pearson, G. Karapetrov, Physical Review B - Rapids 77, 180506 (2008)
• Guiding superconducting vortices with magnetic domain walls, V. Vlasko-Vlasov, U. Welp, G. Karapetrov, V. Novosad, D. Rosenmann, M. Iavarone, A. Belkin, and W.-K. Kwok, Physical Review B - Rapids 77, 134518 (2008)
• Coexistence and Coupling of Two Distinct Charge Density Waves in Sm₂Te₅", C. Malliakas, M. Iavarone, J. Fedor, M. Kanatzidis, J. of Am. Chem. Soc. 130, 3310 (2008)
• Vortex Lattice Transitions in Artificially-Engineered NbSe₂ Single Crystals Observed by STM M. Iavarone, G. Karapetrov, J. Fedor, D. Rosenman, W. K. Kwok, Physica C, 460-462 , 952 (2007)
• Switching of Magnetic Domains in Permalloy Microstructures Using Two-Dimensional Electron Gas, A. Belkin, J. Fedor, P. Pankowski, M. Iavarone, V. Novosad, G. Karapetrov, V. Cambel, D. Gregusova, R. Kudela, Appl. Phys. Lett. 89, 182513 (2006)
• Characterization of off-axis MgB₂ Epitaxial Thin Films for Planar Junctions, M. Iavarone, G. Karapetrov, A. Menzel, V. Komanicky, H. You, W.K. Kwok,P. Orgiani, V. Ferrando, X.X. Xi, Appl. Phys. Lett. 87 , p. 242506 (2005)
  
• Effect of Disorder in MgB₂ Thin Films, M. Iavarone, A. Koshelev, W.K. Kwok, R. DiCapua, R. Vaglio, A. Pogrebnyakov, X.X. Xi, S.I. Lee,  Phys. Rev. B 71, p.214502 (2005)
• Direct Observation of Geometrical Phase Transitions in Mesoscopic Superconductors by STM, G. Karapetrov, J. Fedor, M. Iavarone, D. Rosenmann, and W.K. Kwok, Phys. Rev. Lett. 95, p.167002 (2005)
• Imaging of Vortex States in Mesoscopic Superconductors, G. Karapetrov, J. Fedor, M. Iavarone, M.T. Marshall, R. Divan, Appl. Phys. Lett. 87, p.162515 (2005)
• MgB₂: Directional Tunneling and Two-Band Superconductivity, M. Iavarone, G. Karapetrov, A. Koshelev, W. K. Kwok, D. Hinks, G. W. Crabtree, W. N. Kang, E.-M. Choi, H. J. Kim, S.-I. Lee, Supercond. Sci. and Tech. 16 p.156 (2003)
• Phase Diagram of Single Crystal MgB₂ G. Karapetrov, U. Welp, A. Rydh, M. Iavarone, W. K. Kwok, G. W. Crabtree, Ch. Marcenat, L. Paulius, T. Klein, J. Marcus, K. H. P. Kim, C. U. Jung, H.-S. Lee, B. Kang, S.-I. Lee, J. Low Temp. Phys. 131 p.1237-1244 (2003)
• Scanning Tunneling Spectroscopy in MgB₂, G. Karapetrov, M. Iavarone, W. K. Kwok, G. W. Crabtree and D. Hinks chapter in the "Studies of High-Tc Superconductors" edited by Narlikar Nova Science Publishers Inc. Chapter 11 in book series: Superconducting Magnesium Diboride, p. 221-228 (2002)
• Two-band Superconductivity in MgB₂, M. Iavarone, G. Karapetrov, W.K.Kwok, G.W. Crabtree, D.G. Hinks, W. N. Kang, Eun-Mi Choi, Hyun Jung Kim, Hyeong-Jin Kim and S. I. Lee, Phys. Rev. Lett. 89, p.187002 (2002)
• Scanning Tunneling Spectroscopy in MgB2, G. Karapetrov, M. Iavarone, W.K.Kwok, G.W. Crabtree, and D.G. Hinks, "", Phys. Rev. Lett. 86, p.4374-4377 (2001)

• Scanning Tunneling Spectroscopy in MgB₂, G. Karapetrov, M. Iavarone, W. K. Kwok, G. W. Crabtree and D. Hinks chapter in the "Studies of High Tc Superconductors" edited by Narlikar Nova Science Publishers Inc. Chapter 11 in book series: Superconducting Magnesium Diboride p. 221-228 (2002)
• Borocarbide Thin Films and tunneling Measurements, M. Iavarone, A.Andreone, A.Cassinese, R.Di Capua, L.Gianni, R.Vaglio, Y.DE Wilde and G.W. Crabtree, NATO Science Series of the Workshop "Rare-Earth Transition-Metal Borocarbides (Nitrides): Superconducting, Magnetic, and Normal State Properties" in Dresden June 14-17, 2000 edited by Karl-Hartmut Muller and Vladimir Narozhnyi
• Superconducting properties of borocarbides and in-situ growth of thin films, A.Andreone, M.Iavarone, R.Vaglio, P.Manini, E.Cogliati, in "Highlights In Stampa.INFM 1996/1997" p. 42 , Microart, Lecco 1999
• Properties of R-Ni₂B₂C (R=Y,Er) Superconducting Thin Films, A. Andreone, C. Aruta, F. Fontana, M. Iavarone, M.L. Russo, R. Vaglio, G.W. Crabtree and Y. De Wilde chapter in the "Studies of High T_c Superconductors" edited by Narlikar, Nova Science Publishers, Inc Vol. 26, p.79-95 (1998)
• Vortex Lattice Structure in LuNi₂B₂C chapter in the book "The Superconducting State in Magnetic Fields : Special Topics and New Trends"(World Scientific), Series on Directions in Condensed Matter Physics, Vol. 14, p. 107-129 (1998)
• R.F. field response of metallic superconductors by microstrip resonators A. Andreone, A. Cassinese, A. Di Chiara, M. Iavarone, A. Ruosi, R. Vaglio, Proceeding of the VIIth Workshop on R.F. Superconductivity, Ed. B. Bonin Vol 2 p. 535-539, Institut National de Physique Nucleaire, Gif sur Yvette, France 1995

• 6,638,895 - Method for Fabrication of high aspect ratio structure of perovskite material, G. Karapetrov, W.K. Kwok, G.W. Crabtree, M. Iavarone, October 28, 2003