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Talk:Giant magnetoresistance - Scholarpedia

# Talk:Giant magnetoresistance

Reviewer A

I find the overall structure of the article and its level of detail appropriate. I do not find significant inaccuracies, and my comments and suggestions are mostly for the sake of clarity in the presentation. I shall go section by section.

Section "Opening paragraph"

The last sentence is not clear. "The origin of the ... conductors". In particular, "the influence of the electron spin". I would rather say "The origin of the GMR is the dependence of the electrical conduction in ferromagnetic materials on the spin state of the carriers (electrons)"

Section "Discovery and first experiments"

1st paragraph:

1) both case -> both cases

2) multilayers going with the -> multilayers due to the

2nd paragraph:

1) but an applied field aligns the magnetizations. -> but can be aligned by and applied field.

3rd paragraph:

1) attracted rapidly -> rapidly attracted

2) the oscillations are superimposed to the -> the oscillations are modulated by the

Section " Spin dependent..."

1st paragraph:

1) Idem comment of opening paragraph above.

Fig.3: In panel (a) it is not clearly indicated that the parabolic carrier densities are for non polarized carriers (s electrons) and the colored DOS are for the polarized d electrons. Panel (b) is explained after panel (c).

I think that the notation of using small "n" for both the electron number (density) and the density of states at the Fermi energy may be confusing. Better choices could be capital "N" or "g" (as used in Ashcroft and Mermin) for the density of states.

paragraph after Eq.6:

1) Explicitly mention that the impurity is an extrinsic origin. Mention that the impurities are magnetic.

2) of several impurities -> of several magnetic types

3) larger then -> larger than

Section "Physics and theoretical..."

Title: I would rather put "... models of the GMR with Current In the layer Planes (CIP-GMR)". Which is more informative and also more consistent with the title of a later section.

1st paragraph:

1) the Fig.1c doesn't really show a perfectly aligned current in the plane, but rather an oblique current, which may confuse the readers. This feature should be explained. Perhaps a figure with a schematic drawing of a device with electrodes attached may help.

2) The last part of the paragraph is confusing. The formula for the resistance is general for two conducting spin channels (it is actually similar to Eq.1 and 2), so it should not have the subindex P. So to make this whole part more clear and precise:

I would first recall the formula of Eq.7 (without the P index), then go about doing the simple estimates of the ratio of GMR by considering the examples of the text. Namely, first the P case with $$r_+ >> r_-$$, which replacing in the general formula, gives $$r_P \approx r_+$$, then make the approximation of thickness << MFP leading to $$r_{AP} = (r_+ + r_-)/4$$. With this, replacing in Eq.7 we get Eq.9, and also the limit case of GMR $$\approx r_-/4 r_+$$, when $$r_+ >> r_-$$.

Paragraph (a):

1) reflections, that only if the -> reflections, that only applies if the

Section "GMR with the Current Perpendicular..."

This section really discusses only the spin accumulation effect, and misses to make explicit the connection between this effect and the GMR. Perhaps the author should describe the spin accumulation with two interfaces in the cases of P and AP configurations.

2nd paragraph:

1) the depolarizing (polarizing) -> the depolarizing (or polarizing, depending the direction of the current). In any case, I think this sentence could be improved for clarity.

3rd paragraph:

1) an example of fit is -> an example is shown

Fig.7: The second panel is not clear. What is plotted in the y-axis? It is said that is the GMR, however, from the units it looks as it is the difference of resistance (what is "A"?). In the caption it is said that when $$A \Delta R \to constant$$, for thickness larger than 20 nm, the MR ratio goes to 0. If there the change in resistance is maximal, why the GMR goes to zero? I guess it is because $$r_P$$ increases rapidly with thickness. This should be made clear in the caption.

Section "Concluding remarks"

1) Magnetic random Access Memory -> Magnetic Random Access Memory

2) transfusion" from a current -> transfusion" from a polarized current

### Reviewer B

Excellent satisfied all the criteria of scholarpedia. Excellent review by referee A