230 research outputs found
Unusual signatures of the ferromagnetic transition in the heavy Fermion compound UMnAl
Magnetic susceptibility results for single crystals of the new cubic
compounds UTAl (T=Mn, V, and Mo) are reported. Magnetization,
specific heat, resistivity, and neutron diffraction results for a single
crystal and neutron diffraction and inelastic spectra for a powder sample are
reported for UMnAl. For T = V and Mo, temperature independent Pauli
paramagnetism is observed. For UMnAl, a ferromagnetic transition is
observed in the magnetic susceptibility at = 20 K. The specific heat
anomaly at is very weak while no anomaly in the resistivity is seen at
. We discuss two possible origins for this behavior of UMnAl:
moderately small moment itinerant ferromagnetism, or induced local moment
ferromagnetism.Comment: 5 pages, 5 figures, to be published in Phys. rev.
Magnetic study of M type doped barium hexaferrite nanocrystalline particles
Co Ti and Ru Ti substituted barium ferrite nanocrystalline particles BaFe12 2xCoxTixO19 with 0 lt;x lt;1 and BaFe12 2xRuxTixO19 with 0 lt;x lt;0.6 were prepared by ball milling method, and their magnetic properties and their temperature dependencies were studied. The zero field cooled ZFC and field cooled FC processes were recorded at low magnetic fields and the ZFC curves displayed a broad peak at a temperature TM. In all samples under investigation, a clear irreversibility between the ZFC and FC curves was observed below room temperature, and this irreversibility disappeared above room temperature. These results were discussed within the framework of random particle assembly model and associated with the magnetic domain wall motion. The resistivity data show some kind of a transition from insulator to perfect insulator around . At 2 K, the saturation magnetization slightly decreased and the coercivity dropped dramatically with increasing the Co Ti concentration x. With Ru Ti substitution, the saturation magnetization showed small variations, while the coercivity decreased monotonically, recording a reduction of about 73 at x 0.6. These results were discussed in light of the single ion anisotropy model and the cationic distributions based on previously reported neutron diffraction data for the CoTi substituted system, and the results of our Mössbauer spectroscopy data for the RuTi substituted system
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