Spin-Current Oscillations in Diluted Magnetic Semiconductor Multibarrier GaMnAs/GaAs: Role of Temperature and Bias Voltage
Round 1
Reviewer 1 Report
Up to present, great attention has been paid on the study of diluted magnetic semiconductor (DMS), such as GaN-based and GaMnAs-based materials, which have good magnetic properties and favorable potentials in information storage and computing. The electronic properties, especially the effects of temperature and bias voltage on the transmission coefficient T(E), spin polarization P(E), and the current density, of multi-DMS layers Ga(1-x) MnxAs and nonmagnetic (GaAs) layers, have been theoretically studied by employing the Transfer Matrix Method in this investigation. And some beneficial outcomes are presented by the authors, which might be helpful to enhance practical application of GaMnAs-based DMS.
The manuscript is carefully prepared but still needs reversion for further improvement. Please refer to the following comments or suggestions in order to meet the publication requirement of the MDPI journals.
(1) What modification had been made to the one-dimensional Schrödinger equation applied in this study? It should be stated clearly in the manuscript.
(2) In Section 3, further discussion about the results obtained by the authors is limited. Moreover, nearly no comparison is presented with previous studies by other researchers.
(3) In Abstract and Conclusion sections, it is better to make detailed suggestion on how to apply the outcomes of this investigation to design or fabrication of the GaMnAs-based DMS spintronics and related devices.
(4) Carefully modification of English writing of the manuscript is necessary, which will be beneficial to the readers who are interested in this work. Please check the words or sentences such as “suitable values (line 23)”, “ameliorating (line 41)”, “Betwixt (line 44), shows an easy integration for quantum structures than others DMS materials (line 54)”, “and the current density for a large number of magnetic (GaMnAs) and (line 82)”, “Figure 1. potential profile of multibarrier structure (line 88)”, “For the scattering or tunneling problem (line 108)”, “We investigate in this simulation three values of temperatures (line 122)”, “the transmission coefficients start from different values when N (line 143)”, “This important behavior (line 178)”, “However, it is opaque for all incident energy in the gap region (213)”, “which was very close to the unity for (line 247)”, “Figure 12 (a-b) displayed (line 305)”, “the current density starts from high values and gradually diminishes (line 327)” etc.
Author Response
| We thank the reviewer for his valuable comments and we present in the following paragraph our answers to his questions: 1)The modification in the Schrödinger equation used in this paper was in the term of spin-dependent potential .In fact, when the holes with spin-up orientation are considered the magnetic layers sandwiched between GaAs layers act as quantum wells and act as barriers for holes with spin-down orientation. The spin-dependent potential was taken from reference [23]. In the revised version of our manuscript, we have added some sentences describing this potential.2) In revised version, we have added some sentences in the section 3 describing the main difference between the transmission coefficients in symmetric and asymmetric structures. In addition, we have added a comparison between our results and previous results presented in references [23]. the obtained results are in accordance with those in ref [23]. 3) yes, in the revised manuscript, we have added in the conclusion part a suggestion on how we can apply the outcomes of this investigation.4) we have deleted some inutile termsThe new words are written with blue colorIn the revised version.
‘’suitable values becomes ‘’values’’ “ameliorating’’ becomes ‘’Enhancing’’ Betwixt among shows provides large number great number Fig 1 b becomes : Potential profile of GaAs/Ga1-xMnxAs multibarrier structure For the scattering or tunneling problem becomes for the tunneling problem. We investigate in this simulation three values of temperatures becomes We consider in this case three values of temperatures “the transmission coefficients start from different values when N” becomes The transmission coefficients present different starting points for different values of N. This important behavior becomes This important result. However, it is opaque for all incident energy in the gap region However, it acts as a barrier for all energies inside the gap region. which was very close to the unity for becomes which equal to one for Figure 12 (a-b) displayed becomes Figure 12 (a-b) shows The current density starts from high values and gradually diminishes. the current density starts from its maximum and dimnishes slowly. |
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The manuscript describes the spin-dependent transmission of a multibarrier structure composed of GaAs/Ga(MnAs). The topic is fascinating, and the results are impressive. However, the theoretical model is too ideal without considering some factors. Without that, the calculation results will be far from experimental results. These factors are:
- The magnetization of Ga(MnAs) is sensitively dependent on the carrier density and the temperature. Thus, the applied voltage to the GaAs/Ga(MnAs) multi junctions will make the current injection to the structure and change the carrier density, leading to different magnetizations on various sections of Ga(MnAs).
- The chemical potential on individual GaAs and Ga(MnAs) is different when these sections are connected to form multi junctions. The chemical potential on both materials will modify as well as change the magnetization and set up the barriers on the interface of junctions, which will influence the transmission.
I think if these factors could not be considered in the theory, the authors should address how these factors will affect the results in the manuscript.
Author Response
| We thank the reviewer for these valuable remarks. In fact, in the present work, we have considered a coherent transport and we have
neglected the electrostatic interaction between holes. We only considered the scattering of the carriers by the electrostatic part of the Mn’s impurity potential. This potential is higher than the interaction between holes (see reference Phys. Rev. B 64 (2001) 140403. In our future work, we will solve the coupled equations Schrödinger and Poisson. This resolution self-consistently permits us the calculation of the chemical potential and provide us a general conclusion about the hole-hole and hole-magnetic ions interactions.
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Author Response File: Author Response.pdf
Reviewer 3 Report
Al-Samehri and Dakhlaoui applied the transfermatrix method
to study the coherrent spin dependent transport of holes
across multilayer structures of GaAs or Ga(x)Mn(1-x)As layers.
I do like that the results are presented in conrete units,
but they did not include at all the actually used potentials
they used for the different sections GaAs or Ga(x)Mn(1-x)As. I can only
assume that they always used the same V(x) in Eqn. (1) for the same
combination of spin and layer type and gate voltage. The different
potentials should be explicitely included in section 2. This oversight
renders their findings in fact un-reproducible. In particular it would
be completely impossible for experimentators to check if the potentials
could be tuned to match observations better.
The geometry (in plane or out of plane) of the ferromagnetic Ga(x)Mn(1-x)As
layers and its relation to spin up and spin down should be included
in the introduction.
The effects of incoherent scattering on the calculated transmissions should
at least be discussed with an estimate. If such devices should ever
be fabricated and spin transport is measured, incoherent scattering
will have to be considered.
The article is well written and should be easily accessible to a wider
audience, I just spotted a few minor spelling issues:
line 91 "we can be linked" -> "we can link"
line 107 please verify the order of the product
line 268 "is occured" -> "occurs"
line 275 "to close the" -> "to"
line 278&279 "the unity" -> "unity"
Author Response
| We thank the reviewer for these valuable remarks.The spin-dependent potential was taken from fig 4 in reference [23]. According to reference [23] this potential depends on the temperature of the system and the spin orientation of holes.In fact, when the holes considered have spin-up orientation, the magnetic layers sandwiched between GaAs layers act as quantum wells and when the holes considered have spin-down orientation, the magnetic layers act as barriers. For simplicity we have assumed that the spin dependent potential dose not make a large change when multiple layers are considered. Similarly, we only considered the scattering of the carriers by the electrostatic part of the Mn’s impurity potential. This potential is higher than the interaction between holes (see reference Phys. Rev. B 64 (2001) 140403. In our future work we plan to solve the Schrödinger equation with the Poisson equation self consistently to discuss the hole-hole interaction and to compare it to the hole-magnetic ions interaction. By a self-consistent resolution, we can conclude about the validity and limits of the present model.
According to the reviewer remarks, we have corrected in the revision version the minor spelling issues: 1) we can be linked" -> becomes "we can link’ 2) is occured" -> becomes "occurs. 3) to close the" -> becomes "to" |
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Thank you for the calrifications.
