Vibrational properties of transition metal surfaces

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Education and Research in Jordan,Challenges
Outlook
Bothina Hamad , Ph.D. Physics Department Univers
ity of Jordan
MCC, August, 3rd, , 2006
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Jordan A Quick Introduction

• Population About 5.25 Millions
• Famous sites
• Petra 3 hours south Amman
• Wadi Rum 4 hours south Amman
• Aqaba 4 hours south Amman
• Jerash 1 hour north Amman
• Climate Special climate, cool for most summer
  days and rainy in the winter time with many
  spectacular sunny days.
• Language Arabic is the official language.
  English is the second language and is spoken
  throughout the country.

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Education In Jordan

• Education is one of the most important things
  that the Jordanian government and people care
  about.
• Jordanian people believe strongly in Education
  and they think that is the key for the future.
• Most of the Jordanians would do anything to send
  their kids to school and then off to the
  universities.
• The Education system in Jordan is one of the best
  systems in the Middle East region. It
  concentrates a lot on the person and it tries to
  take care of the children to put them on the
  right start.

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Higher Education

• Eight public universities with 80,000 students.
• Twelve private universities with 30,000 students.
• Twenty one community colleges with 29,000
  students.
• 25 of total recurrent costs are recovered in the
  public sector.
• Spending on education relative to GNP is greatest
  in the Arab world.
• 1/3 of educational expenditure is given to higher
  education.

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• Jordan University
• Yarmouk University
• Science technology
• University
• Al Al-Bayt University
• Heshemea University
• Al Balqa University
• Muuta University
• Maan University

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The University of Jordan
Competence Excellence
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UJ in Brief

• Established in 1962, UJ is the leading and the
  oldest institution of higher education in Jordan.
  It is often referred to as the mother
  university.
• UJ started with the Faculty of Arts with 167
  students enrolled 5 faculty members.
• Today, it has 18 academic faculties, two
  deanships (research and student affairs), 11
  centers, and many other facilities, including an
  excellent library. The number of faculty members
  stands at about 1200 at present.
• It has a student population, at both the graduate
  and undergraduate levels, of about 38,000.
  Undergraduate students 34,000 Graduate
  students 4,000.
• UJ began with the year system. In 1972-73 it
  switched to the credit-hour system. It was the
  first in the Arab-World to do so. The faculties
  of Medicine, and Dentistry are the only
  exceptions.

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Location

• It is located in Amman (the white city), the
  capital of Jordan, a city of about 2 million
  people. Like Rome, originally established on 7
  hills.

Amman
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One-Campus University

• UJ prides itself on the beauty of its
  one-campus university. Nestled on a spacious area
  of 120 Ha (1,200 dunums) , the landscape is
  composed of flat ground and mild slopes covered
  with evergreen pines, elms and olive trees.

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Status

• UJ is a public university it is
  semi-independent, neither totally state-run or
  supported, nor privately endowed or invested.
• UJ is, at once, national, regional, and
  international.

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Undergraduate Programs

• Regular Program the Unified Coordination
  Admission Bureau coordinates general admission
  for all public universities in the Kingdom
  according to the regulations of the Higher
  Education Council.
• 2. Parallel Program for students with
  non-Jordanian nationalities/certificates, or for
  the students who were not accepted through the
  Regular Program.

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Graduate Programs

• Masters Program
• There are two tracks for the Master's degree (36
  credit hours)
• Non-thesis track, in which students must pass a
  comprehensive exam after successfully finishing
  the courses required by the program's Study Plan.
•  
• Master's thesis track requires the student, in
  addition to successfully finishing the courses
  required by the Study Plan, to conduct research,
  and subsequently submit and defend a Master's
  thesis.
• The maximum period is 6 semesters in both tracks.
• TOEFL is required.

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Graduate Programs

• Ph.D. Program
• Maximum of 10 semesters.
• 54 credit hours (36 hours courses, 18 hours
  thesis)
• Qualifying Exam
• TOEFL Required
•  

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Faculty members

• The majority of the faculty members are USA and
• Europe graduates. Some are UJ graduates .
• They are chosen in standards of high merits.

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Teaching duties
Rank Hours per week
Assistant Professor Associate Professor Full Professor 12 hours 12 hours 9 hours
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Distribution of Faculty Members at UJ
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Humanities Social Sciences Scientific
Faculties
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A) Overall Gender Distribution of Faculty Members
at UJ
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82
Male Female
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Students Body

• UJ is proud of choosing the top students in
  Jordan with high academic achievement and
  excellence.
• Strong international presence more than 77
  countries represented on campus, and over 12 are
  international students.
• Diverse students varieties from the country, the
  region, and the globe. Gender, ethnic, race
  diversity.

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A) Overall Gender Distribution of Students at UJ
40
60

Male Female
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B) Gender Distribution of Students
Scientific Faculties
Humanities and Social Sciences
52
48
67
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Male Female
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Gender Distribution of Graduate Students at UJ
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56
Male Female
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Faculty of Science

• Established in 1965 by departments of
  Mathematics, Physics, Chemistry and Biological
  Sciences with 112 students and 5 faculty members.
  
• present student enrollment reached more than
  2000 undergraduate as well as about 321 graduate
  students, and 121 faculty members.
• In 1973, the Department of Geology was added .
• Department of Computer Science in 1982 that
  becomes King Abdullah II School for Information
  Technology in 2000.
• In 2002, the Mathematics department added an
  Actuarial science program.
• In 2004, the Biology department added a Medical
  analysis program.

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Physics Department

• The Department has 26 Faculty members engaged in
  teaching of about 350 students.
• Research in the Physics Department
• Experimental Physics
•   Nanoscience and nanotechnology
•   Material Science
•   Solid State
•   Research in Medical Imaging
•   Laser Spectroscopy
• Theoretical Physics
•   Theory of Condensed Matter Physics
  (Bose-Einsten condensation, Quantum field
  theory).
•   Computational Physics (Magnetism, catalysis)

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Members of the Physics Department
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Resources of Funds

• Deanship of scientific research.
• The higher council of science technology.
• Mango center.
• HOWEVER
• These resources are very SMALL as compared to the
  real need!
• Most of the Jordanian scientists are depending on
  external funds external donations.

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Research Challenges at UJ

• Acute shortage of funds ( minor contribution from
  UJ).
• Non-relevance of programs ( No funds from
  industry to create motivated research projects ).
• No grants resources to create Postdoc
  opportunities.
• No resources for Ph.D. scholarships to have full
  time Ph.D. students.
• No budget to invite scientists.
• Negligible resources for organizing conferences
  at UJ.
• A very small support for scientists
  contributions in international conferences.

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My Group Members

• Bothina Hamad (Assistant Prof.)
• Hanan Saadi (M.Sc. Student)
• Bilal Al-Qasem (Ph.D. Student)
• Ihsan Ereekat (Ph.D. Student)
• Joining Soon
• Ashraf Fadous (M.Sc. Student)
• Ziad Quda (M.Sc. Student)
• Condition
• If I can find some external resources for
  computational power !!!!!

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Resources

• 4 P4 computers.
• 5 (64 AMD dual opterons) machines.
• A Donation from Alexander von Humboldt
  Foundation.
• Problems
• Difficulties in setting up the linux cluster.
• No cooling system.
• No UPS .

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Fields of Interests
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Fields of Interests

• (2) Structures and dynamics
• of transition metal surfaces

• Surface Relaxation

Phonons
DFT Interpolations
DFT calculations
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(3) Catalysis

• Oxide formation and oxidation catalysis at
  transition metal surfaces (CO oxidation on
  transition-metal surfaces).
• We have just started
•  

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(1) MAGNETISM(A) Magnetic structure of
transition-metal surfaces and interfaces
Fe, Co Ni are the only bulk ferromagnetic
materials in nature. Transition metals are good
candidates for fabricating artificial magnetic
structures of materials that are paramagnetic in
their bulk. i.e. (surfaces, overlayers
ultrathin films)
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Magnetic structure of artificial structures is
attributed to the following

1. The decrease in the coordination number

2. The increase of the interatomic spacing .
3. The induction of magnetized neighboring atoms .
Density of states near Fermi level increases
satisfying Stoner criterion (Jn(Ef)gt1) that
gives rise to the appearance of magnetism.
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Semi-empirical Calculation
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Results

• Iron-Vanadium Systems
• Bulk vanadium is paramagnetic.
• V interfaces exhibit induced magnetism when they
  are brought in contact with magnetic materials.
• Low dimensional V monolayers exhibit appreciable
  local magnetic moments.

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(ii)
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V overlayer in V/Fe(001) Bulk V
Ef
Stoner Criterion J n(Ef )gt 1
J v0.5 eV
Local Density of States (States/atom. eV)
Energy (eV)
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The magnetic moment (in Bohr Magnetons) for
surface V atoms and atoms of Mo sublayer in
V/Mo(103) system.
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The average magnetization ( in Bohr magnetons)
for the V/Mo(10 k) stepped structures
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(B) Interlayer Exchange Coupling
Still Magnetism

• The interlayer exchange coupling (IEC) between
  magnetic layers separated by a non-magnetic
  spacer has attracted considerable interest due to
  their interesting properties such as the
  oscillation between ferromagnetic (FM) and
  antiferomagnetic (AF) coupling, and giant
  magnetoresistance (GMR).

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What s GMR?
GMR is the change in electrical resistance in
response to an applied magnetic field .It was
discovered that the application of a magnetic
field to Fe/Cr multilayer resulted in a
significant reduction of the electrical
resistance of the multilayer.
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GMR Applications
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A study of IEC of CoIrn Superlattices

• In order to use such superlattices in GMR
  applications and spin injection, the
  magnetic-nonmagnetic materials should have band
  structure matching. Cobalt-iridium (Co-Ir) system
  is an interesting system for studying the IEC due
  to the band matching between the two elements.
  Investigations are done using FP-LAPW (WIEN2k).

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Ir
Co-spin up
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2nd volume optimization (constant c/a) c/a Ratio (constant volune) 1st volume optimization (constant c/a) Structure
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Interlayer Exchange coupling (IEC)
d is the thickness of the spacer layer
total energies of
FM
AF
arrangements
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IEC using LSDA
IEC Using LSDA
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IEC using GGA
IEC Using GGA
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Results
--The IEC flips from ferromagnetic to
antiferromagnetic at 4.94 Å and 10.25 Å.
--The period of oscillation is found to be 5.31
Å for the LSDA as well as the GGA
approximation in agreement with experiment.
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Magnetic moments (in Bohr magnetons) for each
layer in the Co/Ir unit cell using GGA
approximation. Results are shown for one Co
layer on top of up to 7 Ir layers.
Co Ir1 Ir2 Ir3 Ir4 Ir5 Ir6 Ir7
0.97993 0.134
1.42499 0.026 0.026
1.65864 0.129 -0.079 0.129
1.67722 0.169 -0.046 -0.046 0.169
1.65462 0.127 -0.043 -0.020 -0.043 0.127
1.70254 0.135 -0.055 -0.001 -0.001 -0.055 0.135
1.69909 0.145 -0.045 -0.008 0.028 -0.008 -0.045 0.145
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Magnetic moments (in Bohr magnetons) for each
layer in the Co/Ir unit cell using LSDA
approximation. Results are shown for one Co
layer on top of up to 7 Ir layers.
Co Ir1 Ir2 Ir3 Ir4 Ir5 Ir6 Ir7
0.8888 0.110
1.26837 0.021 0.021
1.53664 0.114 -0.063 0.114
1.53591 0.136 -0.036 -0.036 0.136
1.51666 0.105 -0.035 -0.016 -0.035 0.105
1.57306 0.113 -0.041 0.000 0.000 -0.041 0.113
1.56612 0.117 -0.038 -0.006 0.021 -0.006 -0.038 0.117
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Magnetic moments on Co atoms in CoIrn multilayers
as a function of Ir spacer layer using GGA
calculations
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CONCLUSIONS of the IEC

• We obtained an oscillatory behavior for the
  interlayer exchange coupling with a period of 5.3
  Å for both LSDA as well as GGA.
• The induced magnetism exhibit an AF interlayer
  coupling in Ir spacer.
• The local magnetic moment on Co layers increases
  as a function of spacer thickness until it
  saturate.

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Challenges

• 1. IEC energies are of the order of (0.1 to 1
  meV) per unit cell, i.e., considerably smaller
  than the total energy of the system, this makes
  numerical convergence of the calculations a
  tedious problem.
• 2. Computational time increases rapidly with the
  size of the unit cell, which makes the
  investigation of long-period oscillations
  problematic.

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(2) Structural and Dynamical Properties of
Ru(0001) surface
Motivation The debate between theory and
experiment about the first layer
relaxation. Experiment d12-2 Theory d12-4
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• Is this discrepancy due to
• a temperature effect?
• surface vibrations that are approximated by bulk
  values in LEED calculations?
• a defect in the DFT calculations?

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The recipe to resolve this dispute?
1. Molecular Dynamics Simulations to test the
effect of temperature (T gt 0).
2. Test of the effect of vibrations on LEED
Calculations.
2. Thorough DFT calculations of clean Ru(0001)
surface with well-converged basis set different
XC functionals.
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1. Molecular Dynamics Simulations
DFT calculations T 0K LEED measurements
T100K
Is it a temperature effect?
A scheme using DFT combined with classical MD
simulations is performed.
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DFT Calculations
114 DFT energy points for Ru(0001) using -
WIEN2K (APWlo) - GGA for functional -
Surface described by a supercell of 6 atomic
layers 13Å vacuum.
Interpolation Using 2D Thin-Plate Splines
Classical MD Simulations Using Velocity-Verlet
method Time step dt 0.1f s Total time
50 ps
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RecipeChoose an initial point (structural
configuration) defined by(x, y) coordinates
corresponding to the relaxation(d12 and d23 of
the 1st and 2nd layers.
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MD Simulations
U (Potential Energy)
Time step dt 0.1f s Total time 50 ps
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Ru(0001), MD simulation
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2. Test of the effect of vibrations on LEED
Calculations
A test of the effect of vibrations on the IV LEED
curves for surfaces compare with the effect of
structure.
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No effect of vibration
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3. Is it an XC Problem?
BUT, are these XC functional reliable for Ru
surface??
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L. Wang D. Johnson, J. Phys. Chem.109, 23113
(2005)
Most probably our problem is related to the XC
functional?!
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Outlook

• We are looking forward to achieve the following
  goals
• Establishing long-term collaborations with
  colleagues all over the world.
• Looking for grants and Joint projects that help
  Jordanian scientists to cover Ph.D. scholarships,
  inviting scientists etc.
• Creating a program of exchange visits for the
  graduate students from USA and Jordan.
• Searching for resources to organize conferences,
  workshops and summer schools at UJ.
• Searching for possible CPU time slots in
  supercomputers centers to help Jordanian
  scientists to peruse the state of the art
  research.

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Website www.ju.edu.jo
Thank you for your attention