Search

We investigate the structural, magnetic, and electrical properties of charge-spin co-doped Ba1-x-yLax+yTi1-xMxO3 (M = Cr, Fe, and Co). For Ba1-x-yLax+yTi1-xCrxO3, carrier doping induces short-range ferromagnetism, and we find a large negative magnetoresistance in these compounds. However, for Ba1-x-yLax+yTi1-xMxO3 (M = Fe and Co), the magnetism does not seem to couple with the charge carriers. The transport properties of Ba1-x-yLax+yTi1-xCrxO3 can be described by a three-dimensional variable-range-hopping model that implies itinerant charge carriers, whereas almost all the samples of Ba1-x-yLax+yTi1-xMxO3 (M = Fe and Co) exhibit high resistivity. It is known that only the itinerant charge carriers can enhance the coupling of two isolated magnetic ions. Therefore, there is almost no long-range ferromagnetism in the studied system. [ABSTRACT FROM AUTHOR]

We report the detailed investigations of the magnetic properties, electronic transport, and specific heat in Zn-doped antiperovskite compounds Ga1-xZnxCMn3. Magnetic measurements indicate the metastability of the antiferromagnetic (AFM)-ferromagnetic intermediate (FI) phase transition and the coexistence of different magnetic phases at lower temperature. The enhanced giant magnetoresistance (GMR) is observed with a maximum value of 70% spanning a temperature range of 100 K at 50 kOe. The analysis of heat capacity reveals that the metastability of the AFM-FI transition and the enhanced GMR observed in Ga1-xZnxCMn3 may originate from the reconstruction of Fermi surface accompanying AFM-FI transition. [ABSTRACT FROM AUTHOR]

We report an enhanced negative giant magnetoresistance (GMR) with larger temperature span in Ni-doped antipervoskite compounds GaCMn3-xNix. The observed GMR can peak at ∼75% (at 85 kOe) and exceed 60% (at 50 kOe) over a temperature span of approximate 110 and 50K for x=0.05 and 0.10, respectively. Compared with the parent GaCMn3, the well-enhanced GMR in Ni-doped samples is suggested to be associated with the partially suppressed antiferromagnetic (AFM) ground state, which favors the transition from the high-resistivity AFM state to the low-resistivity canted ferromagnetic state under an external magnetic field. [ABSTRACT FROM AUTHOR]