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.

Korean Language and Korean Studies in Hong Kong (1998–2009)

Hong Kong has a relatively short history of Korean Studies, although Hong Kong has had strong economic relations with Korea for more than 50 years. The main purpose of this study is to examine the development of Korean language learning and Korean Studies in Hong Kong. For this, a series of surveys were conducted among Korean language learners in Hong Kong. From the surveys, it was found that most Korean language learners have a strong interest in Korean popular culture. It was also found that due to the Korean wave (Hallyu), the image of Korea and its people has improved significantly over the last decade. However, the strong interest in Korean popular culture and Hallyu is not sufficient for Korean Studies or Korean major programs to grow further. In order to attract more students into these programs, it may be necessary to cooperate with Korean firms in Hong Kong to provide students with more employment opportunities.published_or_final_versio

Spacetime structure of 5D hypercylindrical vacuum solutions with tension

We investigate geometrical properties of 5D cylindrical vacuum solutions with a transverse spherical symmetry. The metric is uniform along the fifth direction and characterized by tension and mass densities. The solutions are classified by the tension-to-mass ratio. One particular example is the well-known Schwarzschild black string which has a curvature singularity enclosed by a horizon. We focus mainly on geometry of other solutions which possess a naked singularity. The light signal emitted by an object approaching the singularity reaches a distant observer with finite time, but is infinitely red-shifted.Comment: revtex4, 5 pages, 2 figures. To appear in the proceedings of the 10th Asia Pacific Physics Conference (APPC10), Pohang, Korea, 21-24 Aug. 2007. Submitted to J. Korean Phys. Soc. Penrose diagram has been adde