HYbrid MAgnetic Carriers

Boissiere, M., Allouche, J., Brayner, R., Chaneac, C., Livage, J. and Coradin, T. Design of iron oxide/silica/alginate HYbrid MAgnetic Carriers (HYMAC). Journal of Nanoscience and Nanotechnology, in press. 

Surface-modified negatively charged magnetic NPs with grafted PAA layer were adsorbed on the surface of PNIPAM miaogels modified by adsorption of polycations (PDADMAC). New hybrid core-shell microgel possesses a unique combination of thermoresponsivity and magnetism that could open up novel prospeas for remotely controlled dmg carriers. 

The room temperature electrical resistivities of the undoped Eu chalcogenides are above 10 ohm-cm, so that at the temperature of magnetic order the resistivity for all practical reasons is infinite and no effect of residual free carriers can be expected. In spite of this it must be made clear that this does not mean that the compounds are perfect and stoichiometric. There is always a possibility that Eu " ions are present which then act as acceptors. If these acceptor states are within kT above the 4f states or even below the 4f levels we are always left with a hole in the 4f states which remains localized, unless the 4f states are hybridized with other (p) bands and a transfer of holes into these bands is possible. 

The simplest hybrid stracture is a photodetector with an exclusion contact of n, p Jt, Nv, or Pjt type placed in a crossed electric and magnetic held. Figure 3.74 shows as an example an n v type device. The sample is a thin plate of a narrow-bandgap semiconductor, its thickness comparable to the carrier diffusion length. 

The TM-d bands of the transition metal hybridize with the host valence bands (N-p bands in GaN) to form the tetrahedral bonding. This hybridization gives rise to the exchange interaction between the localized 3d spins and the carriers in the host valence band. In the simplest of pictures, the s band of the conduction band does not mix with the TM-d bands, but it is still influenced by the magnetic ion. 

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