In order to search for promising candidates for spintronic applications, this paper systematically studies three ternary compounds based on Mn5Ce3 by using a full-potential linearized augmented plane wave method within the density functional theory. Through structure optimization and electronic structure calculations, it finds that Mn4FeCe3 and MnaCoCe3 have much higher spin-polarization than original intermetallic compound Mn5Ce3, although the spin polarization of MnaNiCe3 is lower than that of Mn5Ce3. The calculated result is in agreement with experiment in the case of Mn4FeCe3. Both of them can be taken as promising candidates for spintronics applications because of their high spin-polarization and compatibility with semiconductors.
A single crystalline Mg2Si film was formed by solid phase reaction （SPR） of a Si（111） substrate with an Mg overlayer capped with an oxide layer（s）,which was enhanced by post annealing from room temperature to 100℃ in a molecular beam epitaxy （MBE） system.The thermal stability of the Mg2Si film was then systematically investigated by post annealing in an oxygen-radical ambient at 300℃,450℃ and 650℃,respectively.The Mg2Si film stayed stable until the annealing temperature reached 450℃ then it transformed into amorphous MgOx attributed to the decomposition of Mg2Si and the oxidization of dissociated Mg.
We have investigated the exchange bias and training effect in the ferromagnetic/antiferromagnetic （FM/AF） heterostructures using a unified Monte Carlo dynamical approach. The magnetization of the uncompensated AF layer is still open after the first field cycling is finished. Our simulated results show obvious shift of hysteresis loops （exchange bias） and cycling dependence of exchange bias （training effect） when the temperature is below 45 K. The exchange bias field decreases with decreasing cooling rate or increasing temperature and the number of the field cycling. Essentially, these two effects can be explained on the basis of the microscopical coexistence of both reversible and irreversible moment reversals of the AF domains. Our simulations are useful to understand the real magnetization dynamics of such magnetic heterostructures.
Carbon nanomaterials,including the one-dimensional(1-D) carbon nanotube(CNT) and two-dimensional(2-D) graphene,are heralded as ideal candidates for next generation nanoelectronics.An essential component for the development of advanced nanoelectronics devices is processing-compatible oxide.Here,in analogy to the widespread use of silicon dioxide(SiO2) in silicon microelectronic industry,we report the proof-of-principle use of graphite oxide(GO) as a gate dielectrics for CNT field-effect transistor(FET) via a fast and simple solution-based processing in the ambient condition.The exceptional transistor characteristics,including low operation voltage(2 V),high carrier mobility(950 cm2/V-1 s-1),and the negligible gate hysteresis,suggest a potential route to the future all-carbon nanoelectronics.
FU WangYang,LIU Lei,WANG WenLong,WU MuHong,XU Zhi,BAI XueDong & WANG EnGe Beijing National Laboratory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China
