Comment on Weak localization in GaMnAs: evidence of impurity band transport by L. P. Rokhinson et. al. (Phys. Rev. B, 76, 161201 R; arXivCond-mat:0707.2416)
We suggest that negative magnetoresistance in small magnetic fields at temperatures lower than 3 K reported in the paper under discussion may be related to superconducting transition in In leads (with Tc = 3.4 K).
We report the observation of negative magnetoresistance in the ferromagnetic semiconductor GaMnAs at low temperatures ($T<3$ K) and low magnetic fields ($0< B <20$ mT). We attribute this effect to weak localization. Observation of weak localization provides a strong evidence of impurity band transport in these materials, since for valence band transport one expects either weak anti-localization due to strong spin-orbit interactions or total suppression of interference by intrinsic magnetization. In addition to the weak localization, we observe Altshuler-Aronov electron-electron interactions effect in this material.
In recent paper Cao et al. [Phys. Rev. B {bf 67}, 161101 (R) (2003)] reported an observation of what is the first genuine multi-mode behavior in random lasers. They observed a splitting of a single lasing line into two lines with close frequencies when pumping is increased beyond a certain threshold. Here we are pointing out that the qualitative interpretation of these experiments given in that paper is misleading.
The recent paper by V. G. Kogan and J. Schmalian Phys. Rev. B 83, 054515 (2011) argues that the widely used two-component Ginzburg-Landau (GL) models are not correct, and further concludes that in the regime which is described by a GL theory there could be no disparity in the coherence lengths of two superconducting components. This would in particular imply that (in contrast to $U(1)times U(1)$ superconductors), there could be no type-1.5 superconducting regime in U(1) multiband systems for any finite interband coupling strength. We point out that these claims are incorrect and based on an erroneous scheme of reduction of a two-component GL theory. We also attach a separate rejoinder on reply by Kogan and Schmalian. In their reply Phys. Rev. B 86, 016502 (2012) to our comment Phys. Rev. B 86, 016501 (2012) Kogan and Schmalian did not refute or, indeed, discuss the main points of criticism in the comment. Unfortunately they instead advance new incorrect claims regarding two-band and type-1.5 superconductivity. The main purpose of the attached rejoinder is to discuss these new incorrect claims.
N.V. Agrinskaya
,V.I. Kozub
.
(2009)
.
"Comment on Weak localization in GaMnAs: evidence of impurity band transport by L. P. Rokhinson et. al. (Phys. Rev. B, 76, 161201 R; arXivCond-mat:0707.2416)"
.
Agrinskaya
هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا