No abstract

No abstract

No abstract

Spintronics is a new and emerging field in nanotechnology, which has been evolving rapidly. It aims to exploit the spin degree of freedom in order to realise advanced electronic devices. With the recent improvement in the storage media devices following to the discovery of giant magnetoresistance effect, it is envisioned that the electronic devices have several advantages over the conventional electronics in respect to the storage capacity, speed and power consumption. One avenue towards next generation spintronic devices is to develop half-metallic ferromagnets (HMFs) with 100% spin polarisation (P) and Curie temperature (T C ) above room temperature (RT). HMFs have unique properties, in which the majority spins have a metallic band structure, whereas the minority spins have a semiconducting band with the Fermi level (E F ) lying within an energy gap. P of HMFs has been predominantly estimated using Julliere's formula in a magnetic tunnel junction (MTJ) or measured by the Andreev reflection (AR) at low temperature. Both methods are very sensitive to the surface/interface spin polarisation.Alternative optical methods such as photoemission have also been employed. However, these methods require a complicated and expensive set-up. Therefore, it is of paramount importance to directly and easily measure the band-gap of HMFs.The main aim of this study is to develop a new technique to directly measure the band-gap (E g ) of HMFs at RT. For that, a simple experimental set-up has been designed This technique allows measuring E g of HMFs at RT for the first time. It can therefore be used to provide simple optimisation of growth conditions.iii