Education:

Feb 20013: Assistant Prof. degree in Theoretical and Experimental Solid State Physics.

Al-Askaria Secondary School, Sohag (Egypt).

Experience:

2017/….. :        Teaching lectures in Physics for 3^rd and 4^th levels: Statistical Physics,        

                              Electrodynamics, Theory of Electromagnetism, Physical Electronics, Physical         

                              optics and Electricity and Magnetism in Sohag University.

2009/2017: Teaching Lectures in General Physics (Phys 1) and (Phys 2), Quantum Mechanics,   

                              Modern Physics, Classical mechanics, Theory of Electromagnetism, Applied 

                              Electronics, Solid state Physics, for the university College student, Aljamoum-

                              University College, Umm-Elqura  University Makkah, KSA.

Optics, Electricity, Oscillators, Semiconductors (1^th, 2^nd, 3^rd and 4^th year Educational faculty.

Occupation:

versity, Egypt.

statement of research interests :

• Study the magneto caloric effect in the magnetic material experimentally and theoretically to enhance the magnetic properties in order to get new magnetic refrigerators materials.

• Obtaining the critical exponents for the thermal physical quantities using the Monte Carlo simulation for the Ising model.

Theory of magnetism with temporal disorder applied to magnetically doped ZnO: Insulating ZnO is magnetic when doped with transition metals but this magnetization decreases rapidly as the carriers become mobile1. The magnetic interaction is mediated by occupied polaron orbits because the electron orbits associated with defects are exchange coupled to several magnetic ions. In the variable hopping regime the conductivity varies is controlled by the parameter T0 that characterizes the probability of the carriers can hop between localized states. When a carrier moves out of a localised orbit the exchange interactions between the transition metal ions are changed suddenly. This time dependence of the exchange interactions destroys the ferromagnetism.

We simulate an Ising model with ferromagnetic bonds J and antiferromagnetic bonds - J with probability 1-q and q respectively. This is ferromagnetic for qqc. We change the arrangement of the AF bonds after n Monte Carlo steps but keeping the same value of q. This random flipping of the exchange interactions differs from the Glauber model in which the Ising model is subjected to a random external field. The spin glass phase is characterised by long relaxation times however the relaxation become slow even in the ferromagnetic phase as q increases. The ferromagnetism is destabilised by the time dependent exchange even though the average exchange =J(1-2q) is still positive. The phase diagram is calculated as a function of q and n.

The Theory of the Relaxation Phenomena in Manganites as a PhD degree with Prof.

Gillian.

1. A study is made of an anisotropic Potts model in three dimensions where the coupling depends on both the Potts state on each site but also the direction of the bond between them using both analytical and numerical methods. The phase diagram is mapped out for all values of the exchange interactions. Six distinct phases are identified. Monte Carlo simulations have been used to obtain the order parameter and the values for the energy and entropy in the ground state and also the transition temperatures. Our Monte Carlo calculations have been carried out on 3d finite cubic lattices (with linear size L = 8) with periodic boundary conditions. All our simulations have made use of the Metropolis algorithm with the spin being chosen at random, and with averaging performed over 10⁵ Monte Carlo steps per site. In most of the phase diagram this gave clear results. Where convergence was slow we checked that we had found the true ground state by both increasing the number of Monte Carlo steps and also by looking at a L = 10 lattice as explained below. Results at low temperatures were obtained by cooling down from a hightemperature random configuration. Excellent agreement is found between the simulated and analytic results. We find one region where there are two phase transitions with the lines meeting in a triple point. The orbital ordering that occurs in LaMnO₃ occurs as one of the ordered phases.
2. A modified Potts model based on the physics of the manganese-oxygen bonds and two different exchange interaction types, J₁ and J₂ , were proposed. The orbital ordering in LaMnO₃ is obtained when J₁ is AF and J₂ is FM. Local short range order is obtained above Jahn-Teller temperature, T_JT , and it reduced the entropy from kBloge3 to s_sro ∼ (0.50.02) and this value is well comparable to the experimental value obtained by Sanchez. When J₁ is AF and J₂ is zero a line phase which represents orbital ordering disorder in LaMnO₃ above T_JT is obtained . This line phase has no transition and its entropy is higher than s_sro.

Transport properties of the Ga_0.45In_0.55Sb Alloy, as a Master degree with prof. M. Ibrahim, prof. Mostafa M. Abd El-Rahim and prof. A. M. Aly . We have studied the transport properties of the composition Ga_0.45In_0.55Sb in terms of studying the conduction behaviour, the thermoelectric power (S), the Hall coefficient (R_H), the charge carrier mobility (µ), the charge carrier concentration (n) and the magneto-resistance coefficient (R_M). On the other hand, the structural properties are characterised by means of the XRD analysis, DTA and scanning electron microscopy.It is propositioning that most of the transport properties are investigated in a wide range of temperature 173 ≤ T ≤ 400K, applied magnetic field 0.0607 ≤ B ≤ 0.765 Tesla and annealing was carried out isochronically in the range 50 ≤ T_an ≤ 400^oC.

Research skills:

I have good knowledge of writing Fortran programs, simulating realistic systems using Monte Carlo and statistical models such as Ising models and Potts models, fitting experimental data, solving some quantum problems.

Computer skills:

I have a good knowledge of UNIX/LINUX, WINDOWS and MS-DOS operating systems. I have been programming using FORTRAN language. I use LaTeX as well as Word in writing my manuscripts.

Languages:

English, Arabic (mother tongue).

Publications:

• The phase Diagram for an anisotropic Potts model, R. Ahmed and G. A. Gehring, J. Phys. A: Math. Gen. 38, 4047 (2005).
• Potts model for distortion transition in LaMnO₃, Mahrous R. Ahmed and G. A. Gehring, Phys. Rev. B 74, 014420 (2006).
• Magneto-optical study of the Verwey transition in magnetite, J. R. Neal, A. J. Behan, A. Mokhtari, R. Ahmed, H. J. Blythe, A. M. Fox, G. A. Gehring, J. Mag. Mag. Mater. 310, (2007) 246.
• The spin Frank-Condon Effect, Mahrous R. Ahmed and G. A. Gehring, J. Phys.: Condens.

Matter 19, 256208 (2007).

• Transport Properties of Ga_0.45In_0.55Sb, M. M. Abd El-Raheem, M. M. Ibrahiem, A. M. Ahmed and R. Ahmed, Egypt. J. Solids 30, 31-46 (2007).
• Investigation of zirconium oxynitride thin films deposited by reactive pulsed magnetron sputtering, S H Mohamed, A M Abd El-Rahman and Mahrous R. Ahmed, J. Phys. D: Appl. Phys. 40, 7057(2007).
• Theory of magnetism with temporal disorder applied to magnetically doped ZnO, G A Gehring, Mahrous R Ahmed, A J Crombie, J. App. Phys. 105, 1-3(2009).
• The volume collapse in LaMnO₃ modelled using an anisotropic Potts model, Mahrous R Ahmed and G A Gehring, Phys. Rev B. 79, 174106 (2009).
• Nitrocarburizing of AISI-304 stainless steel using high-voltage plasma immersion ion implantation, A.M. Abd El-Rahman, S.H. Mohamed, M R. Ahmed, E. Richter, F. Prokert, Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 267, 10, 1792-1796 (2009).
• Landau theory of compressible magnets near a quantum critical point, Gillian A. Gehring1, and Mahrous R. Ahmed, JOURNAL OF APPLIED PHYSICS 107, 09E125 2010
• Correlation of Magnetoresistance and Thermoelectric Power in La1-xLixMnOy Compounds, Ahmed Mohamed Ahmed, Mahrous R Ahmed, Abed El Rahman Ahmed Saad, Journal of Electromagnetic Analysis and Applications, 2011, 27-2.

[12] Electrical and magnetic transport in strontium doped europium Ferrimanganites, I.A. Abdel-Latif, Mahrous R. Ahmed, I.A. Al-Omari, A. Sellai,  Journal of Magnetism and Magnetic Materials Volume 420, 15 December 2016, Pages 363–370.

[13] Effect of charge ordering on the electrical properties and magnetoresistance of manganites, Mahrous R. Ahmed, https://arxiv.org/abs/1803.02283.

References:

1. G A Gehring

Department of Physics and Astronomy,

University of Sheffield

Sheffield, S3 7RH, UK.

Fax (44) 0114 22 23555

E-mail: g.gehring@shef.ac.uk

2. Peter Littlewood ,

Head of the Department of Physics,

The Cavendish Laboratory,

University of cambridge, 19, J J Thomson Avenue Cambridge, CB3 HE, UK.

Tel: +44 (0)1223 337254

Fax: +44 (0)1223 337356

E-mail:pbl21@cam.ac.uk

3. D M Whittaker

Department of Physics and Astronomy,

University of Sheffield

Sheffield, S3 7RH, UK.

Fax (44) 0114 22 23555

E-mail: d.m.whittaker@shef.ac.uk

4. Ahmed M. Aly Physics Department,

Faculty of sciences

Sohag University,

82524, Sohag, Egypt. Tel : + 20 93 4602 965 fax : + 20 93 4601 950

E-mail: fikry₋9970@yahoo.com