Laboratory of Nanoscale Condensed Matter
Group of Surfaces and Interfaces

Main research subjects


  • Ferroelelectric surfaces: interplay structure – composition – polarization, chemistry and photochemistry at these surfaces, heterostructures
  • Magnetism: surface magnetism, diluted magnetic semiconductors, multiferroics
  • Catalysis and photocatalysis
  • Semiconductor surfaces, heterostructures, molecular assemblies and chemical reactions
  • 2D materials and phenomena associated with ferroelectrics or semiconductors
  • Nanoparticles and clusters, other low-dimensional systems
  • Molecular electronics and spintronics

Techniques


  1. Photoelectron spectroscopy based: X-ray photoelectron spectroscopy (XPS), high resolution synchrotron radiation based photoelectron spectroscopy (PES), angle resolved photoelectron spectroscopy (ARPES), photoelectron diffraction (PED), ultraviolet photoelectron spectroscopy (UPS), angle-resolved UPS (ARUPS), spin-resolved UPS, photoemission electron microscopy (PEEM).
  2. X-ray absorption based: Extended X-ray absorption fine structure (EXAFS), X-ray absorption near edge structure (XANES), near-edge X-ray absorption spectroscopy (NEXAFS) including dichroic effects, X-ray magnetic circular dichroism (XMCD).
  3. Electron diffraction based: low energy electron diffraction (LEED), reflection high energy electron diffraction (RHEED), low energy electron microscopy (LEEM).
  4. Auger electron spectroscopy (AES), Auger electron diffraction (AED).
  5. Variable temperature scanning tunneling microscopy (STM), scanning tunneling spectroscopy (STS).
  6. Mass spectroscopy: residual gas analysis (RGA) using quadrupole mass spectrometers (QMA), thermal desorption analysis, Wien filters, gas chromatography – mass spectroscopy (GC-MS), secondary ion mass spectroscopy (SIMS).
  7. Positron annihilation-induced Auger electron spectroscopy.
  8. Sample preparation: molecular beam epitaxy, chemical syntheses.
  9. Ultrahigh vacuum devices: design, realization, operation.

Group members


Names Degree Position Hirsch Index
Cristian Mihail Teodorescu PhD, Habil. Senior Scientist I, Group leader h = 24
Nicoleta Georgiana Apostol PhD Senior Scientist II h = 13
Marius Adrian Hușanu PhD Senior Scientist II h = 10
Rodica Ghiță PhD Senior Scientist II h = 8
Constantin Cătălin Negrilă PhD Senior Scientist III h = 14
Bogdana Lenuța Borca PhD Senior Scientist III h = 11
Constantin Logofătu PhD Senior Scientist III h = 10
George Adrian Lungu PhD Senior Scientist III h = 10
Florentina Neațu PhD Senior Scientist III h = 10
Ștefan Neațu PhD Senior Scientist III h = 10
Ruxandra Maria Costescu PhD Senior Scientist III h = 8
Dana Georgeta Popescu PhD Senior Scientist III h = 6
Laura Elena Abramiuc PhD student Researcher h = 7
Liviu Cristian Tănase PhD student Researcher h = 3
Costel Cotîrlan-Simioniuc PhD Research Assistant h = 4
Amelia Elena Bocîrnea PhD student Research Assistant h = 1
Cristian Alexandru Tache PhD Engineer -
Ioana Cristina Bucur PhD student Engineer -
Eugen Petru Tudor - Technician I -
Cornelia Stoicu - Technician II -
Marius Stoicu - Worker -

On leave:

Names Degree Position Hirsch Index
Ana Maria Trandafir PhD student Research Assistant h = 1

Former members of the team:

Names Degree Position
Dan Macovei PhD Senior Scientist I
Adrian Ștefan Manea PhD Senior Scientist I
Mihail Florin Lăzărescu PhD Senior Scientist I

Representative publications during the last decade

(corresponding author belonging to the group)

  1. Low temperature two-dimensional behaviour of spin and orbital moments in Ni monolayers grown on Cu(100)
    C.M. Teodorescu
    Surf. Sci. 601, 4292-4296 (2007).
  2. Spectral response of Au-Ti Schottky barrier on semi-insulating GaAs
    R.V. Ghita, C. Logofatu, C. Negrila, C. Cotirlan, P. Ghita, A.S. Manea, M.F. Lazarescu
    Phys. Stat. Solidi A 204, 1025-1029 (2007).
  3. Angle-resolved XPS structural investigation of GaAs surfaces
    C.C. Negrila, C. Logofatu, R.V. Ghita, C. Cotirlan, F. Ungureanu, A.S. Manea, M.F. Lazarescu
    J. Cryst. Growth 310, 1576-1582 (2008).
  4. Nanostructured thin layers of vanadium oxides doped with cobalt, prepared by pulsed laser ablation: chemistry, local atomic structure, morphology, and magnetism
    C.M. Teodorescu , G. Socol, C. Negrila, D. Luca, D. Macovei
    J. Exper. Nanosci. 5, 509-526 (2010).
  5. Significantly different contamination of atomically clean Si(001) when investigated by XPS and AES
    N.G. Gheorghe, G.A. Lungu, R.M. Costescu, C.M. Teodorescu
    Phys. Stat. Solidi B 248, 1919-1924 (2011)
  6. Atomic structure and reactivity of ferromagnetic Fe deposited on Si(001)
    N.G. Gheorghe, M.A. Husanu, G.A. Lungu, R.M. Costescu, D. Macovei, C.M. Teodorescu
    J. Mater. Sci. 47, 1614-1620 (2012).
  7. X-ray photoelectron spectroscopy of pulsed laser deposited Pb(Zr,Ti)O3-δ
    C. Dragoi, N.G. Gheorghe, G.A. Lungu, L. Trupina, A.G. Ibanescu, C.M. Teodorescu
    Phys. Stat. Solidi A 209, 1049-1052 (2012).
  8. Epitaxial ferromagnetic samarium and samarium silicide synthesized on Si(001)
    N.G. Gheorghe, M.A. Husanu, G.A. Lungu, D. Macovei, I. Pintilie, D.G. Popescu, C.M. Teodorescu
    J. Mater. Sci. 47, 7225-7234 (2012).
  9. Structure, reactivity, electronic configuration and magnetism of samarium atomic layers deposited on Si(001) by molecular beam epitaxy
    N.G. Gheorghe, G.A. Lungu, M.A. Husanu, R.M. Costescu, D. Macovei, C.M. Teodorescu
    Appl. Surf. Sci. 267, 106-111 (2013).
  10. Room temperature ferromagnetic, anisotropic, germanium rich FeGe(001) alloys
    G.A. Lungu, N.G. Apostol, L.E. Stoflea, R.M. Costescu, D.G. Popescu, C.M. Teodorescu
    Materials 6, 612-625 (2013).
  11. Charge transfer and band bending at Au/Pb(Zr,Ti)O3 interfaces investigated by photoelectron spectroscopy
    N.G. Apostol, L.E. Stoflea, G.A. Lungu, C. Chirila, L. Trupina, R.F. Negrea, C. Ghica, L. Pintilie, C.M. Teodorescu
    Appl. Surf. Sci. 273, 415-425 (2013).
  12. Band bending in Au/Pb(Zr,Ti)O3 investigated by X-ray photoelectron spectroscopy: dependence on the initial state of the film
    N.G. Apostol, L.E. Stoflea, G.A. Lungu, L.C. Tanase, C. Chirila, L. Frunza, L. Pintilie, C.M. Teodorescu
    Thin Solid Films 545, 13-21 (2013).
  13. Band bending at free Pb(Zr,Ti)O3 surfaces analyzed by X-ray photoelectron spectroscopy
    N.G. Apostol, L.E. Stoflea, G.A. Lungu, C.A. Tache, D.G. Popescu, L. Pintilie, C.M. Teodorescu
    Mater. Sci. Eng. B 178, 1317-1322 (2013).
  14. Epitaxial growth of Au on Ge(001) surface: photoelectron spectroscopy measurements and first-principles calculations
    D.G. Popescu, M.A. Husanu
    Thin Solid Films 552, 241–249 (2014).
  15. Au-Ge bonding on uniformly Au-covered Ge(001) surface
    D.G. Popescu, M.A. Husanu
    Physica Status Solidi – Rapid Research Letters 7, 274-277 (2013).
  16. Room temperature ferromagnetic Mn:Ge(001)
    G.A. Lungu, L.E. Stoflea, L.C. Tănase, I.C. Bucur, N. Răduţoiu, F. Vasiliu, I. Mercioniu, V. Kuncser, C.M. Teodorescu
    Materials 7, 106-129 (2014).
  17. Schottky barrier versus surface ferroelectric depolarization at Cu/Pb(Zr,Ti)O3 interfaces
    L.E. Stoflea, N.G. Apostol, C. Chirila, L. Trupina, R. Negrea, L. Pintilie, C.M. Teodorescu
    J. Mater. Sci. 49, 3337-3351 (2014).
  18. Selective adsorption of contaminants on Pb(Zr,Ti)O3 surfaces shown by X-ray photoelectron spectroscopy
    L.E. Ştoflea, N.G. Apostol, L. Trupină, C.M. Teodorescu
    J. Mater. Chem. A 2, 14386-14392 (2014).
  19. The evanescent-wave cavity ring-down spectroscopy technique applied to the investigation of thermally grown oxides on Si(100)
    C. Cotirlan-Simioniuc, R.V. Ghita, C.C. Negrila, C. Logofatu
    Appl. Phys. A 117, 1359-1365 (2014).
  20. Spectro-microscopic photoemission evidence of charge uncompensated areas in Pb(Zr,Ti)O3 (001) layers
    D.G. Popescu, M.A. Huşanu, L. Trupină, L. Hrib, L. Pintilie, A. Barinov, S. Lizzit, P. Lacovig, C.M. Teodorescu
    Phys. Chem. Chem. Phys. 17, 509 - 520 (2015).
  21. Image molecular dipoles in Surface Enhanced Raman Scattering
    C.M. Teodorescu
    Phys. Chem. Chem. Phys. 17, 21302-21314 (2015).
  22. Photoelectron spectroscopy and spectro-microscopy of Pb(Zr,Ti)O3 (111) thin layers: imaging ferroelectric domains with binding energy contrast
    M.A. Huşanu, D.G. Popescu, C.A. Tache, N.G. Apostol, A. Barinov, S. Lizzit, P. Lacovig, C.M. Teodorescu
    Appl. Surf. Sci. 352, 73-81 (2015).
  23. Band bending at copper and gold interfaces with ferroelectric Pb(Zr,Ti)O3 investigated by photoelectron spectroscopy
    N.G. Apostol, L.E. Ştoflea, L.C. Tănase, I.C. Bucur, C. Chirilă, R.F. Negrea, C.M. Teodorescu
    Appl. Surf. Sci. 354, 459-468 (2015).
  24. Surface topography to reflectivity mapping in two-dimensional photonic crystals designed in germanium
    M.A. Husanu, C.P. Ganea, I. Anghel, C. Florica, O. Rasoga, D.G. Popescu
    Appl. Surf. Sci. 355, 1186-1191 (2015).
  25. Influence of hole depletion and depolarizing field on the BaTiO3/La0.6Sr0.4MnO3 interface electronic structure revealed by photoelectron spectroscopy and first-principles calculations
    D.G. Popescu, N. Barrett, C. Chirila, I. Pasuk, M.A. Husanu
    Phys. Rev. B 92, 235442 (2015).
  26. Correlation of optical reflectivity with numerical calculations for a two-dimensional photonic crystal designed in Ge
    M.A. Husanu, D.G. Popescu, C.P. Ganea, I. Anghel, C. Florica
    Eur. Phys. J. D 69, 273 (2015).
  27. Growth mechanisms and band bending studies in Cu and Pt on Ge(001) investigated by LEED and photoelectron spectroscopy
    L.C. Tănase, A.E. Bocîrnea, A.B. Șerban, L.E. Abramiuc, I.C. Bucur, G.A. Lungu, R.M. Costescu, C.M. Teodorescu
    Surf. Sci. 653, 97-106 (2016).
  28. Non-interacting, sp2 hybridized carbon layers on ferroelectric lead zirco-titanate
    N.G. Apostol, G.A. Lungu, I.C. Bucur, C.A. Tache, L. Hrib, L. Pintilie, D. Macovei, C.M. Teodorescu
    RSC Adv. 6, 67883-67887 (2016).
  29. Ferroelectric triggering of carbon monoxide adsorption on lead zirco-titanate (001) surfaces
    L.C. Tănase, N.G. Apostol, L.E. Abramiuc, C.A. Tache, L. Hrib, L. Trupină, L. Pintilie, C.M. Teodorescu
    Sci. Rep. 6, 35301 (2016).
  30. The methanolysis and heterogeneous photocatalysis combined action in the decomposition of chemical warfare agents
    N. Petrea, R. Petre, G. Epure, V. Șomoghi, L.C. Tănase, C.M. Teodorescu, Ș. Neațu
    Chem. Commun. 52, 12956-12959 (2016).
  31. Aspects of native oxides etching on n-GaSb(100) surface
    C. Cotirlan, R.V. Ghita, C.C. Negrila, C. Logofatu, F. Frumosu, G.A. Lungu
    Appl. Surf. Sci. 363, 83-90 (2016).
  32. XPS analysis of AuGeNi/cleaved GaAs(110) interface
    C.C. Negrila, M.F. Lazarescu, C. Logofatu, C. Cotirlan, R.V. Ghita, F. Frumosu, L. Trupina
    J. Nanomater. 7574526 (2016).
  33. Long range magnetic interaction in MnxGe1-x: structural, spectro-microscopic and magnetic investigations
    L.C. Tănase, G.A. Lungu, L.E. Abramiuc, I.C. Bucur, N.G. Apostol, R.M. Costescu, C.A. Tache, D. Macovei, A. Barinov, C.M. Teodorescu
    J. Mater. Sci. 52, 3309-3320 (2017).
  34. Polarization landscape effects in soft X-ray-induced surface chemical decomposition of lead zirco-titanate, evidenced by photoelectron spectromicroscopy
    L.E. Abramiuc, L.C. Tănase, A. Barinov, N.G. Apostol, C. Chirilă, L. Trupină, L. Pintilie, C.M. Teodorescu
    Nanoscale 9, 11055-11067 (2017).
  35. Structural and magnetic properties of Ni nanofilms on Ge(001) by molecular beam epitaxy
    A.E. Bocîrnea, R.M. Costescu, I. Pasuk, G.A. Lungu, C.M. Teodorescu
    Appl. Surf. Sci. 424, 337-344 (2017).
  36. Band bending and magnetism at Ni/Ge(001) interface investigated by X-ray photoelectron spectroscopy
    A.E. Bocîrnea, L.C. Tănase, R.M. Costescu, N.G. Apostol, C.M. Teodorescu
    Appl. Surf. Sci. 424, 269-274 (2017).
  37. Low energy electron diffraction from ferroelectric surfaces. Dead layers and surface dipoles in ultraclean Pb(Zr,Ti)O3(001)
    C.M. Teodorescu, L. Pintilie, N.G. Apostol, R.M. Costescu, G.A. Lungu, L. Hrib, L. Trupină, L.C. Tănase, I.C. Bucur, A.E. Bocîrnea
    Phys. Rev. B 96, 115438 (2017).
  38. Triggering surface ferroelectric order in Pb(Zr,Ti)O3(001) by deposition of platinum
    I.C. Bucur, L.C. Tănase, L.E. Abramiuc, G.A. Lungu, C. Chirilă, L. Trupină, N.G. Apostol, R.M. Costescu, L. Pintilie, C.M. Teodorescu
    Appl. Surf. Sci., accepted (2017). DOI: 10.​1016/​j.​apsusc.​2017.​04.​238.

Experimental setups


  1. Cluster comprising (i) a molecular beam epitaxy (with in situ LEED, RHEED and AES), sample preparation facilities (sputtering, annealing, plasma source, Knudsen cells, electron bombardment), residual gas analysis; (ii) a variable temperature scanning tunneling microscopy (STM – STS) – Aarhus 150; and (iii) a photoemission chamber with spin resolution (XPS, ARPES, PED, UPS, ARUPS, SR-UPS). Actually, this cluster is delocalized on the SuperESCA beamline at the Elettra synchrotron radiation facility and is available to external users. Romanian teams have reserved 6 days of beamtime per semester, and the Institute has granted 5 days of in-house research per semester. Outside synchrotron radiation runs, the cluster is available at any momen to work using conventional techniques. Excitation sources for photoelectron spectroscopy: monochromated Al Kα (1486.7 eV)/ Ag Lα (2984.3 eV) radiation, high power (300 W) UV lamp with He I (21.2 eV) and He II (40.8 eV) radiation, synchrotron radiation (120 – 1200 eV). Manufacturer: Specs GmbH, Germany.






  2. STM on graphene grown on Ir(111). From left to right image ranges 10 x 10, 20 x 20, 30 x 30 Å2. Moiré fringes are quite visible.


    (a – e) Cleaning to the atomic level of Pb(Zr,Ti)O3(001) surfaces concomitant with setting of the inwards polarization state, followed by photoelectron spectroscopy. (f) LEED patterns are readily observable; reproduced from Sci. Rep. 6, 35301 (2016).

  3. Cluster comprising (i) a molecular beam epitaxy (with in situ LEED, RHEED and AES), sample preparation facilities (sputtering, annealing, Knudsen cells, electron bombardment), residual gas analysis, gas line; (ii) a scanning tunneling microscopy (STM – STS); and (iii) a photoemission chamber (XPS, UPS). Excitation sources for photoelectron spectroscopy: monochromated Al Kα (1486.7 eV) radiation, dual anode Al Kα (1486.7 eV) / Mg Kα (1253.6 eV), UV lamp with He I (21.2 eV) radiation. Manufacturer: Specs GmbH, Germany.


  4. Proof of self-doping (oxygen vacancy creation) in ultrathin Pb(Zr,Ti)O3-δ layers by analyzing separately the stoichiometry of components ascribed to different polarization states; reproduced from Sci. Rep. 5, 14974 (2015).

  5. Full automated installation for X-ray photoelectron spectroscopy with spatial resolution (2 μm) coupled to a cell for online driven chemical reactions on surfaces at high temperatures (1000 °C) and pressures (4 bar), with 4-ways gas line and exhaust. Excitation source for photoelectron spectroscopy: monochromated Al Kα (1486.7 eV) radiation, dual anode Al Kα (1486.7 eV) / Mg Kα (1253.6 eV). Manufacturer: Kratos Analytical Inc., U.K.







  6. Spatially resolved characterization of electrode diffusion and iodine migration from (CH3 NH3 )PbI3 solar cells; reproduced from J. Phys. Chem. Lett. 7, 5168, (2017).

  7. Setup for low energy electron microscopy and photoemission electron microscopy (LEEM – PEEM). Available methods: (i) LEEM in bright and dark field with a lateral resolution of 4 nm; (ii) Photoemission electron microscopy (PEEM) with several UV excitation sources (Hg lamp and He I - He II lamp), lateral resolution about 15 nm; (iii) Mirror electron microscopy (MEM); (iv) Micro-low energy electron diffraction (Micro-LEED); (v) k-space mapping with sub-micron lateral resolution (individual grains); (vi) recording LEEM, PEEM, MEM, LEED movies in real time during thermal treatments, ion sputtering or thin layer growth. Manufacturer: Specs GmbH, Germany.




  8. LEEM dark field images on one of the diffraction spots (1/2, 0) of the Si(001) surface reconstruction. The field of view is 3 μm.

  9. Setup for laboratory extended X-ray absorption fine structure (EXAFS). Excitation: Mo Ka1 (17479.34 eV), W La1 (8397.6 eV) lines, power 3 kW (40 kV, 75 mA); monochromators Ge(220), Ge(111), Ge(311), Ge(400), Ge(840), Si(400); detectors: selected proportional counters, scintillation counters; measurement in transmission or fluorescence; analysis software. Manufacturer Rigaku Corp., Japan.






  10. Ultrathin films of Mn diffused into Ge: local atomic order probed by EXAFS. Magneto-optical Kerr effect revealed Mn ferromagnetism when the substrate temperature exceeds 250 °C.

  11. Chemistry laboratory: contains basic apparatus (glass flasks, balance, ultrasonic baths, vortex, bi-distillated water equipment, pressure reactors, heating and stirring systems, photocatalytic reactors, safety equipment, etc.) to support preparation of catalysts and performance of heterogeneous catalytic reactions (oxidation, hydrogenation, coupling reactions, photocatalytic reactions, etc.) and energy-efficient reactions (methane steam reforming, water splitting, etc.).
    The laboratory is design also to assist analytical methods for identification of chemical products resulted from reactions (GC-MS QP2010 Ultra from Shimadzu). The GC-MS solution equipment disposed of two injectors, two detectors (MS and BID), pressure valve for real time analysis, auto-sampler and is able to deliver information about gaseous and volatile liquids compounds.



  12. Separation of p-cymene oxidation products (p-cymene, methyl-acetophenone, terephthaldehyde, isopropyl benzoic acid and p-toluic acid) by GC-MS QP2010 equipped with an Elite-5MS capillary column 30m x 0.25 mm, 0.25 μm from PerkinElmer.

Contact





Contact Person: Cristian Mihail Teodorescu

National Institute of Materials Physics

Atomistilor Str., No. 405A PO Box MG 7, 077125, Magurele, Romania

Telephone: +40-(0)21-3690185, +40-(0)21-2418100

Fax: +40-(0)21-3690177