Maeda Laboratory research

Abstract

For the development of materials, Maeda and Dr Fuyuki Nabeshima – an Assistant Professor in Maeda Laboratory – have been working on thin-film synthesis, including an artificial ‘super lattice’, using pulsedlaser deposition for the past six years. The film superconductors have demonstrated extraordinary promise for high critical current density samples, and ultra-thin films composed of the same materials have been reported to be superconducting at extremely higher critical temperatures bulk samples of the same material. The second direction involves the behaviour of quantised magnetic vortices in the aforementioned materials. In high temperature superconductors, the equilibrium phase diagram has been viewed as largely different from that known in conventional superconductors. Of particular interest to Maeda and his team has been the so-called flux flow phenomenon, where vortices suffer from the force of the supercurrent and start to move. For the past 15 years the group has investigated a means to precisely estimate the flux flow if these vortices using microwave surface impedance measurements. Importantly, they have discovered that the vortices suffer from large dissipation which is something that has never previously been considered in any theories of superconductivity. The third direction has resulted in a variety of measurement techniques of high frequency complex conductivity in cryogenic circumstances. Of particular importance to this strand of enquiry is the team’s development of the microwave microscope which has enabled them to observing AC conductivity distribution in iron-based superconductors. In combination, the three directions represent genuine potential for the realisation of something that will have direct positive impact on humanity.