23 research outputs found
The synthesis and characterization of 1111-type diluted magnetic semiconductors (La1-xSrx)(Zn1-xTMx)AsO (TM = Mn, Fe, Co)
The doping effect of Sr and transition metals Mn, Fe, Co into the direct-gap
semiconductor LaZnAsO has been investigated. Our results indicate that the
single phase ZrCuSiAs-type tetragonal crystal structure is preserved in
(La1-xSrx)(Zn1-xTMx)AsO (TM = Mn, Fe, Co) with the doping level up to x = 0.1.
While the system remains semiconducting, doping with Sr and Mn results in
ferromagnetic order with TC ~ 30K, and doping with Sr and Fe results in a spin
glass like state below ~6K with a saturation moment of ~0.02 muB/Fe, an order
of magnitude smaller than the ~0.4 muB/Mn of Sr and Mn doped samples. The same
type of magnetic state is observed neither for (Zn,Fe) substitution without
carrier doping, nor for Sr and Co doped specimens.Comment: Accepted for publication in EP
Lattice gas model for fragmentation: From Argon on Scandium to Gold on Gold
The recent fragmentation data for central collisions of Gold on Gold are even
qualitatively different from those for central collisions of Argon on Scandium.
The latter can be fitted with a lattice gas model calculation. Effort is made
to understand why the model fails for Gold on Gold. The calculation suggests
that the large Coulomb interaction which is operative for the larger system is
responsible for this discrepancy. This is demonstrated by mapping the lattice
gas model to a molecular dynamics calculation for disassembly. This mapping is
quite faithful for Argon on Scandium but deviates strongly for Gold on Gold.
The molecular dynamics calculation for disassembly reproduces the
characteristics of the fragmentation data for both Gold on Gold and Argon on
Scandium.Comment: 13 pages, Revtex, 8 figures in ps files, submitted to Phys. Rev.