Magneic-field-enhanced superconductivity

“磁场增强超导”=MFES，即临界磁场随温度升高而增大的超导状态分为这两类。在平行磁场作用下，Al和TiN薄膜的上、下弹簧的无间隙能谱的自旋顺磁分裂诱导了高熵超导态，并在高温下驱动了超导态。另一种是在Au和Ge薄膜叠合界面形成的二维薄膜超导体。在这种情况下，超导态出现在磁场作用下的零场临界温度以上。根据热力学原理，前者为熵驱动超导态（EDS），后者为顺磁驱动超导态（PDS）。对于后者，这种PDS的机制目前尚未确定。边界散射不会引起薄膜的PDS。从临界场的温度依赖性分析来看，认为PDS最合理的机制是由于金属-绝缘体跃迁附近的电子局域化和超导性之间的竞争，即超薄膜中的强局域化是PDS出现的原因。为了理解PDS的机理，需要建立包括电子-电子相互作用在内的金属-绝缘体跃迁附近的超导理论。

"Magnetic-Field-Enhanced Superconducutivity" =MFES,namely, the superconducting state whose critical magnetic field is increased with increasing temperature is classified in the two categories. One is found for thin films of Al and TiN under parallel magnetic fields that the spin paramagnetic splitting of the gapless energy spectra for up and down spings indued high entropy superconducting state and has driven a supercondcuting state at higher temperatures. The other was found for the two dimensional thin film superconductors which was formed at the interface of stacked thin films of Au and Ge. In this case, superconducting state appears above the zero field critical temperature under magnetic fields.According to themodynamics, the former is the entropy driven superconducting stage (EDS) and the latter is a paramagnetically driven superconducting state (PDS). For the latter, the the mechanism of this PDS is not settled so far.The boundary scattering does not cause the PDS for thin films. The most plausible mechanism for PDS is considered to be due to the competition between the electron localization and superconductivity near the metal-insulator transition, that is, the strong localization in ultra thin films is considered to be responsible for the appearance of the PDS from the analysis of the temperature dependence of critical field. Theory of superconductivity near the metal-insulator transition including electron-electron interaction is desired to be established for understanding the mcchanism of PDS.