ترغب بنشر مسار تعليمي؟ اضغط هنا

Comment on Formation Mechanism and Low-Temperature Instability of Exciton Rings

95   0   0.0 ( 0 )
 نشر من قبل Alexander Paraskevov
 تاريخ النشر 2009
  مجال البحث فيزياء
والبحث باللغة English
 تأليف A. V. Paraskevov




اسأل ChatGPT حول البحث

This is an extended version of the Comment that contains the criticism against an applicability of the diffusive transport model for the explanation of the ring-shaped spatial pattern formation in the exciton photoluminescence for the GaAs/AlGaAs double quantum wells [Phys. Rev. Lett. 92, 117404 (2004)]. The model has been used in other similar papers published in the PRL and the PRB afterwards.

قيم البحث

اقرأ أيضاً

The sticking probability of cold atomic hydrogen on suspended graphene calculated by Lepetit and Jackson [Phys. Rev. Lett. {bf 107}, 236102 (2011)] does not include the effect of fluctuations from low-frequency vibrations of graphene. These fluctuati ons suppress the sticking probability for low incident energies ($lesssim 15$ meV).
87 - Taner Yildirim 2008
In a recent paper [arXiv:0804.3569], Takatoshi Nomura {it et al.} reported a structural phase transition near 150 K in LaOFeAs and used space group Cmma to describe their X-ray diffraction data. However, they did not discuss how their proposed struct ure compares with the early neutron study by Cruz {it et al.}[arXiv:0804.0795] where the low temperature structure of LaOFeAs was described by space group P112/n. This caused some confusion, suggesting that there may be some disagreement on the low temperature structure of LaOFeAs as evidenced by several inquiries that we received. Here we show that the proposed structures from x-ray and neutron diffraction are basically identical. The P2/c (i.e., P112/n) cell becomes the primitive cell of the Cmma cell when the z-coordinate of the oxygen and iron are assumed to be exactly 0 and 0.5 (these numbers were reported to be -0.0057 and 0.5006 in neutron study). Our first-principles total-energy calculations suggest that the oxygen and iron atoms prefer to lie on the z=0 and 1/2 plane, respectively, supporting Cmma symmetry. However it is more convenient to describe the structural distortion in the primitive P2/c cell which makes it easier to see the connection between the high (i.e., P4/nmm) and low temperature structures.
Comment on the paper: Magnetization Process of Single Molecule Magnets at Low Temperatures of J.F.Fernandez and J.J.Alonso (PRL 91, 047202 (2003)).
We study the formation of an exciton condensate in GaAs coupled quantum wells at low temperatures. We show that the condensate consists of dark excitons, and extends over hundreds of {mu}m, limited only by the boundaries of the mesa. We find that the condensate density is determined by spin flipping collisions among the condensate excitons and with the thermal bath. We show that these processes, which convert dark excitons to bright, evaporatively cool the system to temperatures that are much lower than the bath temperature. We present a rate equations model, which explains the temperature and power dependence of the exciton density, and in particular - the large density buildup at low temperatures. We confirm the validity of the model by reproducing the unique behavior observed when a magnetic field is applied in a direction parallel to the layers.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا