Modulation of the Curie Temperature in Ferromagnetic/Ferroelectric Hybrid Double Quantum Wells

We propose a ferromagnetic/ferroelectric hybrid double quantum well structure, and present an investigation of the Curie temperature (Tc) modulation in this quantum structure. The combined effects of applied electric fields and spontaneous electric polarization are considered for a system that consists of a Mn \delta-doped well, a barrier, and a p-type ferroelectric well. We calculate the change in the envelope functions of carriers at the lowest energy sub-band, resulting from applied electric fields and switching the dipole polarization. By reversing the depolarizing field, we can achieve two different ferromagnetic transition temperatures of the ferromagnetic quantum well in a fixed applied electric field. The Curie temperature strongly depends on the position of the Mn \delta-doped layer and the polarization strength of the ferroelectric well.Comment: 9 pages, 5 figures, to be published in Phys. Rev. B (2006) minor revision: One of the line types is changed in Fig.

New identities involving q-Euler polynomials of higher order

In this paper we give new identities involving q-Euler polynomials of higher order.Comment: 11 page

Pion form factors with improved infrared factorization

We calculate electromagnetic pion form factors with an analytic model for $\alpha_{\rm s}(Q^2)$ which is infrared (IR) finite without invoking a ``freezing'' hypothesis. We show that for the asymptotic pion distribution amplitude, $F_{\pi ^{0}\gamma ^{*}\gamma}$ agrees well with the data, whereas the IR-enhanced hard contribution to $F_{\pi}$ and the soft (nonfactorizing) part can jointly account for the data.Comment: 12 pages; 3 figures as PS files (1 figure added); modified text; added references. To appear in Phys. Lett.

Inclusive angular distribution of alpha and Li fragments produced in the Fe-C and Fe-Pb collisions at 1.88 GeV/u

The LS (laboratory system) emission angles theta for 2188 and 298 Li fragments, produced inclusively in relativistic Fe-C and Fe-Pb collisions, have been measured in reference to incident Fe-ion beam tracks nearby in nuclear emulsion. An empirical differential frequency formula, dN(cot theta) = exp (a + b cot theta)d(cot theta) is obtained with the constant b approx. = -0.026 at 1.88 GeV/u, which seems to be independent on the kinds of target nucleus as well as on the kinds of projectile fragments