College of Science / Department of Physics

Mahmoud Khaled Abusamak


Professor
Mahmoud Khaled Abusamak

Curriculum Vitae
  • Major: Solid state physics
  • College: College of Science
  • Department(s): Physics Department
  • E-mail: mabusamak@ahu.edu.jo
  • Phone No.: 0096232179000ُExt6332

PRESENT POSITION

 Associate Professor

Experiences

A) Doctoral Work: High Temperature Superconductors (HTC). Inda

B) Post-doctoral Work: Surface Science (Low dimensional physics). Italy

C) Visiting Scientist: Nanophysics and Material Science. Canada and USA

 

The doctoral work , Post-doctoral , Visiting Scientist, present and future  work are/ were carried out using the synchrotron radiation facilities as well as lab facilities using XAS, and XPS and UV spectroscopy facility at ELETTRA (ITALY), LURE (FRANCE), Grenoble (FRANCE), and CLRC Daresbury  (ENGLAND). CLS Canadian Light source CANADA and ALS Advanced Light Source Berkeley and SLAC Stanford accelerator (USA)

 


We are studying the electronic structures of new and advanced materials. We are using synchrotron radiation to perform soft x-ray emission and absorption spectroscopy of systems like biomaterials, superconductors and transition metal compounds. The AREAS OF INTEREST are:
1) Surface Science/ Low- dimensional and nano physics 2) Semiconductors and Superconductors. 3) Synchrotron Radiation Facilities. 4) UV Photoemission Spectroscopy. 5) X-ray Photoemission Spectroscopy. 6) X-ray Absorption Spectroscopy. 7) X-ray emission Spectroscopy. 8) High Temperature Superconductors

Study of Band Structure Properties of Pnictide LaO1−xFxFeAs (x = 0, 0.2) Superconducting
  • Research Summary
    • This paper reports on the band structure properties and changes in band structure of fluorine-doped LaO1−xFxFeAs (x = 0, 0.2) compound, measured using X-ray photoemission spectroscopy (XPS). The band structure of the superconducting compound is compared with nonsuperconducting parent compound LaOFeAs. With fluorine doping, a shift of the shallow core level is observed in XPS spectra, which may be a response of the band structure due to fluorine doping in the system. The balance of the chemical potential shift with the screening effect of conduction electrons near the Fe and As ions is discussed using nearly unchanged Fe 2p and As 3d core-level spectra. The La 3d core-level spectra shift towards the high energy, ∼0.36eV, may bedue tothe chemical potential shift caused by fluorine doping. In our valence band spectra, a small peak at around 0.2 eV is observed, which disappeared with the fluorine doping in the system, indicating a change of Fe 3d state from low spin to high spin states and also confirming the nature of Fe 3d electrons as itinerant, which is responsible for superconductivity in these compounds.
  • Research link
  • key words
    XPS·Valence band·LaO1−xFxFeAs
Effect of thermal annealing on some electrical properties and optical band gap of vacuum evaporated Se65Ga30In5 thin films
  • Research Summary
    • Electrical properties and optical band gap of amorphous Se65Ga30In5 thin films, which were thermally evaporated onto chemically cleaned glass substrates, have been studied before and after thermal annealing at temperatures above the glass transition temperature and below the crystallization temperature. The IeV characteristics, which were recorded in the temperature range (200e300 K), were obtained at different voltages and exhibit an ohmic and non-ohmic behavior at low (0e5 V) and high (5 e18 V) voltages, respectively, for annealed and as-prepared films. Analysis of the experimental data in the high voltage range confirms the presence of space charge limited conduction (SCLC) for annealed and as-prepared films. The dependence of DC conductivity on temperature in the low voltage region shows two types of conduction channels: The first is in the range 270e300 K and the other at the lower temperature range (200e270 K). The conduction in the first region is due to thermally activated process, while in the other is due variable range hopping (VRH) of charge carriers in the band tails of the localized states. After annealing, the conductivity has been found to increase but the activation energy decreases. This is attributed to rupturing of SeeIn weak bonds and formation of SeeGa strong bonds. This process changes the concentration of defects in the films which in turn decreases the density of states N(EF) as predicted by Mott’s VRH model. Analysis of the absorption coefficient of annealed and as-prepared films, in thewavelength range 300e700 nm, reveals the presence of parabolic densities of states atthe edges of both valence and conduction bands in the studied films. The optical band gap (Eg) was obtained through the use of Tauc’s relation and is found to decrease with annealing temperature
  • Research link
  • key words
    Thermal annealing Electrical properties Optical band gap Thin films Chalcogenide glasses
Valence Structure of Alkaline and Post-Transition Metal Oxides
  • Research Summary
    • As a stepping point to predicting band gaps and electronic structure of more complicated materials based on alkaline and post-transition metal oxides, we examine the valence structure of these simple binary oxides using both high resolution X-ray emission spectroscopy and a variety of density functional theory calculations. We confirm that the new modified Becke-Johnson (mBJ) extension of the Perdew-Burke-Ernzerhoff (PBE96) functional provides a good estimate of the band gaps of these materials, but we demonstrate that it does not provide an accurate depiction of the valence structure in post-transition metal oxides. A calculation with an exact Hartree-Fock exchange energy does a better job of calculating the valence structure, but no longer accurately reproduces the band gap. Since we expect that d-p repulsion may play an important role in shaping the band gap, we suggest that combining the valence structure from the latter calculation with the band gap of the former calculation may be the best approach for predicting the electronic structure of more advanced materials based on these post-transition metal oxides precurso
  • Research link
  • key words
    band gaps, ZnO, electronic structure, density functional theory, X-ray emission spectroscopy
Valence Structure of Alkaline and Post-Transition Metal Oxides
  • Research Summary
    • As a stepping point to predicting band gaps and electronic structure of more complicated materials based on alkaline and post-transition metal oxides, we examine the valence structure of these simple binary oxides using both high resolution X-ray emission spectroscopy and a variety of density functional theory calculations. We confirm that the new modified Becke-Johnson (mBJ) extension of the Perdew-Burke-Ernzerhoff (PBE96) functional provides a good estimate of the band gaps of these materials, but we demonstrate that it does not provide an accurate depiction of the valence structure in post-transition metal oxides. A calculation with an exact Hartree-Fock exchange energy does a better job of calculating the valence structure, but no longer accurately reproduces the band gap. Since we expect that d-p repulsion may play an important role in shaping the band gap, we suggest that combining the valence structure from the latter calculation with the band gap of the former calculation may be the best approach for predicting the electronic structure of more advanced materials based on these post-transition metal oxides precursors
  • Research link
  • key words
    band gaps, ZnO, electronic structure, density functional theory, X-ray emission spectroscopy
Correlation effects in Ni 3d states of LaNiPO
  • Research Summary
    • The electronic structure of the new superconducting material LaNiPO experimentally probed by soft X-ray spectroscopy and theoretically calculated by the combination of local density approximation with Dynamical Mean-Field Theory (LDA+DMFT) are compared herein. We have measured the Ni L2,3 X-ray emission (XES) and absorption (XAS) spectra which probe the occupied and unoccupied the Ni 3d states, respectively. In LaNiPO, the Ni 3d states are strongly renormalized by dynamical correlations and shifted about 1.5 eV lower in the valence band than the corresponding Fe 3d states in LaFeAsO. We further obtain a lower Hubbard band at –9 eV below the Fermi level in LaNiPO which bears striking resemblance to the lower Hubbard band in the correlated oxide NiO, while no such band is observed in LaFeAsO. These results are also supported by the intensity ratio between the transition metal L2 and L3 bands measured experimentally to be higher in LaNiPO than in LaFeAsO, indicating the presence of the stronger electron correlations in the Ni 3d states in LaNiPO in comparison with the Fe 3d states in LaFeAsO. These findings are in accordance with resonantly excited transition metal L3 X-ray emission spectra which probe occupied metal 3d-states and show the appearance of the lower Hubbard band in LaNiPO and NiO and its absence in LaFeAsO.
  • Research link
  • key words
    PACS numbers: 71.27.+a, 74.25.Jb, 78.70.En
Effect of thermal annealing on some electrical properties and optical band gap of vacuum evaporated Se65Ga30In5 thin films
  • Research Summary
    • Electrical properties and optical band gap of amorphous Se65Ga30In5 thin films, which were thermally evaporated onto chemically cleaned glass substrates, have been studied before and after thermal annealing at temperatures above the glass transition temperature and below the crystallization temperature. The IeV characteristics, which were recorded in the temperature range (200e300 K), were obtained at different voltages and exhibit an ohmic and non-ohmic behavior at low (0e5 V) and high (5 e18 V) voltages, respectively, for annealed and as-prepared films. Analysis of the experimental data in the high voltage range confirms the presence of space charge limited conduction (SCLC) for annealed and as-prepared films. The dependence of DC conductivity on temperature in the low voltage region shows two types of conduction channels: The first is in the range 270e300 K and the other at the lower temperature range (200e270 K). The conduction in the first region is due to thermally activated process, while in the other is due variable range hopping (VRH) of charge carriers in the band tails of the localized states. After annealing, the conductivity has been found to increase but the activation energy decreases. This is attributed to rupturing of SeeIn weak bonds and formation of SeeGa strong bonds. This process changes the concentration of defects in the films which in turn decreases the density of states N(EF) as predicted by Mott’s VRH model. Analysis of the absorption coefficient of annealed and as-prepared films, in thewavelength range 300e700 nm, reveals the presence of parabolic densities of states atthe edges of both valence and conduction bands in the studied films. The optical band gap (Eg) was obtained through the use of Tauc’s relation and is found to decrease with annealing temperature
  • Research link
  • key words
    Thermal annealing Electrical properties Optical band gap Thin films Chalcogenide glasses
Study of Band Structure Properties of Pnictide LaO1−xFxFeAs (x = 0, 0.2) Superconducting
  • Research Summary
    • This paper reports on the band structure properties and changes in band structure of fluorine-doped LaO1−xFxFeAs (x = 0, 0.2) compound, measured using X-ray photoemission spectroscopy (XPS). The band structure of the superconducting compound is compared with nonsuperconducting parent compound LaOFeAs. With fluorine doping, a shift of the shallow core level is observed in XPS spectra, which may be a response of the band structure due to fluorine doping in the system. The balance of the chemical potential shift with the screening effect of conduction electrons near the Fe and As ions is discussed using nearly unchanged Fe 2p and As 3d core-level spectra. The La 3d core-level spectra shift towards the high energy, ∼0.36eV, may bedue tothe chemical potential shift caused by fluorine doping. In our valence band spectra, a small peak at around 0.2 eV is observed, which disappeared with the fluorine doping in the system, indicating a change of Fe 3d state from low spin to high spin states and also confirming the nature of Fe 3d electrons as itinerant, which is responsible for superconductivity in these compounds.
  • Research link
  • key words
    XPS·Valence band·LaO1−xFxFeAs
Valence Structure of Alkaline and Post-Transition Metal Oxides
  • Research Summary
    • As a stepping point to predicting band gaps and electronic structure of more complicated materials based on alkaline and post-transition metal oxides, we examine the valence structure of these simple binary oxides using both high resolution X-ray emission spectroscopy and a variety of density functional theory calculations. We confirm that the new modified Becke-Johnson (mBJ) extension of the Perdew-Burke-Ernzerhoff (PBE96) functional provides a good estimate of the band gaps of these materials, but we demonstrate that it does not provide an accurate depiction of the valence structure in post-transition metal oxides. A calculation with an exact Hartree-Fock exchange energy does a better job of calculating the valence structure, but no longer accurately reproduces the band gap. Since we expect that d-p repulsion may play an important role in shaping the band gap, we suggest that combining the valence structure from the latter calculation with the band gap of the former calculation may be the best approach for predicting the electronic structure of more advanced materials based on these post-transition metal oxides precurso
  • Research link
  • key words
    band gaps, ZnO, electronic structure, density functional theory, X-ray emission spectroscopy
Valence Structure of Alkaline and Post-Transition Metal Oxides
  • Research Summary
    • As a stepping point to predicting band gaps and electronic structure of more complicated materials based on alkaline and post-transition metal oxides, we examine the valence structure of these simple binary oxides using both high resolution X-ray emission spectroscopy and a variety of density functional theory calculations. We confirm that the new modified Becke-Johnson (mBJ) extension of the Perdew-Burke-Ernzerhoff (PBE96) functional provides a good estimate of the band gaps of these materials, but we demonstrate that it does not provide an accurate depiction of the valence structure in post-transition metal oxides. A calculation with an exact Hartree-Fock exchange energy does a better job of calculating the valence structure, but no longer accurately reproduces the band gap. Since we expect that d-p repulsion may play an important role in shaping the band gap, we suggest that combining the valence structure from the latter calculation with the band gap of the former calculation may be the best approach for predicting the electronic structure of more advanced materials based on these post-transition metal oxides precursors
  • Research link
  • key words
    band gaps, ZnO, electronic structure, density functional theory, X-ray emission spectroscopy
Correlation effects in Ni 3d states of LaNiPO
  • Research Summary
    • The electronic structure of the new superconducting material LaNiPO experimentally probed by soft X-ray spectroscopy and theoretically calculated by the combination of local density approximation with Dynamical Mean-Field Theory (LDA+DMFT) are compared herein. We have measured the Ni L2,3 X-ray emission (XES) and absorption (XAS) spectra which probe the occupied and unoccupied the Ni 3d states, respectively. In LaNiPO, the Ni 3d states are strongly renormalized by dynamical correlations and shifted about 1.5 eV lower in the valence band than the corresponding Fe 3d states in LaFeAsO. We further obtain a lower Hubbard band at –9 eV below the Fermi level in LaNiPO which bears striking resemblance to the lower Hubbard band in the correlated oxide NiO, while no such band is observed in LaFeAsO. These results are also supported by the intensity ratio between the transition metal L2 and L3 bands measured experimentally to be higher in LaNiPO than in LaFeAsO, indicating the presence of the stronger electron correlations in the Ni 3d states in LaNiPO in comparison with the Fe 3d states in LaFeAsO. These findings are in accordance with resonantly excited transition metal L3 X-ray emission spectra which probe occupied metal 3d-states and show the appearance of the lower Hubbard band in LaNiPO and NiO and its absence in LaFeAsO.
  • Research link
  • key words
    PACS numbers: 71.27.+a, 74.25.Jb, 78.70.En

1.      A Comparative Study on Optical Characteristics of InGaAsP QW Heterostructures of Type-I and Type-II Band Alignments, G Bhardwaj, K Sandhya, R Dolia, M Abu-Samak, S Kumar, PA Alvi

       Bulletin of Electrical Engineering and Informatics 7 (1), 25-41

 

2.      Optimization of AlGaN QW Heterostructure for UV Applications, R Dolia, M Abu-Samak, PA Alvi, Engineering Vibration, Communication and Information Processing, 9-14

 

3. Simulating 1.55 µm Optical Gain in Type-II InAlAs/InGaAs/GaAsSb Nanoscale Heterostructure

    AM Khan, G Bhardwaj, M Abu-Samak, SH Saeed, PA Alvi, IOP Conference Series: Materials             Science and Engineering 594 (1), 012003


4. SSRL School on Synchrotron X-Ray Absorption Spectroscopy Techniques,    

   Stanford synchrotron radiation Laboratory, California CA, May 20-22, 2008.

5.       The second National workshop on synchrotron users (SESAME) held at Jordan   

    University, Jordan, May 10/5/2007.

6.      The first National workshop on synchrotron users (SESAME) held at Jordan

   University, Jordan, May 10/5/2006.

7.      "LEED, HREELS and photoemission studies of Pseudomorphic growth of alpha-Sn on InSb surfaces", workshop on physics of semiconductor science (WPSS’04) Lattakia- Syria, May 9-11-2004.

8.      "Screw dislocation mediated growth and surface composition of c-axis oriented High Tc superconducting thin film: Scanning Tunneling Microscopy and X-ray Photoemission Spectroscopy" (published in ICITNS October 2003).

 

9.      "Pseudomorphic growth of alpha-Sn on low-index InSb surfaces", (publishesd in ICITNS October 2003, conference at Al-Zaytoonah University,Amman, Jordan).

 

10.  "Density of states of two-dimensional electron gas at semiconductor surfaces", 24th Annual meeting Advances in Surface and Interface Physics and Special Session of INFM Section F with the Synchrotron Light Committee, Dipartimento di Fisica, Modena (Italy), December 20-21.

 

11.  "Investigation of Silver-YBCO interface by XPS and Electrical Measurements", MRS 1995 Spring Meeting held in San Franisco from 18-20 April, 1995.

 

12.  "Seudomorphic growth of alpha-Sn on low-index InSb surfaces. Sandra Gardonio, Paolo Fantini, 24th Annual meeting Advances In Surface and Inerface Physics and Special Session of INFM Section F with the Synchrotron Light Committee, Dipartimento di Fisica, Modena (Italy), December 20-21, 1999.

 

13.  "Characterization of Air formed Oxide Films on Amorphous Ti60Ni40 by EPS", Procd, 37 DAE-SSP Symp. 1994, p. 457.

14.  "AFM & STS Studies of Bi-2212 Single Crystals", Procd. 37   DAE-SSP Symp.1994, p.383

 

 

 

 


1993
1994-1996
JRF (junior research fellowship) from UGC -India
SRF (Senior Research Fellowship) from UGC-India
1996-1997
Research Associate Fellowship from European countries union (ECU).
1999-2000
2007
TRIL (Training and Research in Italian Laboratory) ICTP-Italy
IAEA/SESAME (International Atomic Energy Agency) fellowship (CLS Canadian Light source CANADA and ALS Advance Light Source Berkley, and Stanford light source SLAC ( USA)

      (1)    2004-now

       Associate Professor

       Physics Department,

      Al-Hussein Bin Talal University,

               Ma'an-Jordan

    (2)  2010-2015

    Associate Professor

     Physics Department,

   Al -Baha University

   Al Baha-   Saudi Arabia

 

   (3) 1997-2004

          Assistant Professor

Faculty of Science

         Al-Zaytoonah Jordanian Private University

                    Amman-Jordan

 

            (4) 1999-2000

  Visiting Scientist

           Istituto Nazionale per la Fisica della Materia

     INFM National Center on nanoStructures and bioSystems at Surfaces (S^3),

     via G. Campi 213/A, I-41100 Modena, Italy

          Dept. of Physics, University of Modena e Reggio Emilia

                Modena, Italy

 

      (5)   2008

  Visiting Professor/Scientist

 Department of Physics and Engineering Physics,

       University Of Saskatchewan,

                   SK, CANADA

 

   (6) 1993 - 1996

  Teaching and Research Assistant

  Department of Physics

  Rajasthan University

           Jaipur-India


Courses Taught:

     Solid state physics I,II,  Electronic, Digital Electronics , Electrical and Electronic circuit's analysis , Mathematical Physics I &II, Electromagnetic I & II, Classical Mechanics I & II, Electrodaynamic, Modern physics, Quantum physics I & II, General Physics 101, General Physics 102, , Thermodynamics, , Heat and Waves.  Low temperature physics, Superconductivity,       

 


Academic qualifications and certificates

(1) Diploma (of science) 1985

North Al-Hashmi Secondary School

Amman – Jordan

  (2) B.Sc. in Physics 1985-1989

Ahmedabad  Science College

Gujarat University

Gujarat-India

  (3) M.Sc. in Physics 1989-1992

Department of Physics

Kashmir University

J & K- India

  (4) Ph.D. in Physics 1992-1996

Department of Physics, Rajasthan University, Jaipur-India

 


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