Magnetism in nanoscale systems and intriguing dual nature of ion irradiation
A brief introduction will be given on magnetism in nanoscale systems and how size and shape affect magnetic behaviour. The importance of ion beams in the area of nanoscale magnetism will be illustrated with demonstration of dual roles of ion irradiation, namely, transformation of nonmagnetic materials into magnetic materials and vice versa. In the light of the observed phenomena, future developments in the area of nanotechnology, such as ultrahigh density magnetic storage devices, single-electron spin-valve transistors etc. will be discussed. Some nanoscale structures that can be fabricated using ion beams will offer the possibility of exploring new scientific aspects in these structures
Dark Matter, Dark Energy, Neutrino Mass and Leptogenesis at the TeV Scale
In recent years the most fascinating experimental result in particle physics came out in neutrino physics. The atmospheric and solar neutrino oscillation experiments give a convincing evidence that at least two of the neutrinos are massive, and are of the order of sub-eV. The smallness of neutrino masses depend on a large suppression by the lepton number violating scales. The lepton number violation in the early universe could produce a net lepton asymmetry which was then transferred to a baryon asymmetry,that is observed today, in the presence of electroweak anomalous processes. The present neutrino oscillation data imply that if neutrino masses and leptogenesis are originated from the same source of lepton number violation, then the scale of leptogenesis should be $\geq O(10^9)$ GeV which is far away from the next generation accelerators to be verified.In this talk we will discuss a particle physics model for neutrino masses and leptogenesis at the TeV scale. We ensure that the lepton number violation required for neutrino masses does not conflict with the lepton number violation required for leptogenesis. As a result the model could be extended to explain the dark matter (DM), whichis 23% of the critical energy density, and dark energy (DE), which is 73% of the critical energy density, of the present universe. The most attractive feature of this model is that itpredicts a few hundred GeV triplet Higgs scalar that can be tested at LHC or ILC.
