Effects of Fe doping in the colossal magnetoresistive La12xCaxMnO3
نویسندگان
چکیده
The effect of Fe doping ~,20%! on the Mn site in the ferromagnetic (x50.37) and the antiferromagnetic (x50.53) phases of La12xCaxMnO3 has been studied. Upon doping, no appreciable structure changes have been found in either series. However, conduction and ferromagnetism have been consistently suppressed by Fe doping. Colossal magnetoresistance has been shifted to lower temperatures, and in some cases enhanced by Fe doping. These results are not due to the strong lattice effects commonly seen in doping of the La sites. Rather, replacement of Mn by Fe depopulates the hopping electrons, and weakens the double exchange. The effect of Fe doping can be explained in terms of the band structure. © 1997 American Institute of Physics. @S0021-8979~97!73008-1#
منابع مشابه
Magnetic properties and colossal magnetoresistance of La(Ca)MnO3 materials doped with Fe.
The effect of Fe doping ~,20%! on the Mn site in the ferromagnetic ~x50.37! and the antiferromagnetic ~x50.53! phases of La12xCaxMnO3 has been studied. The same ionic radii of Fe 31 and Mn cause no structure change in either series, yet conduction and ferromagnetism have been consistently suppressed by Fe doping. Colossal magnetoresistance has been shifted to lower temperatures, and in some cas...
متن کاملMössbauer Effect Probe of Local Jahn-Teller distortion in Fe-doped Colossal Magnetoresistive Manganites
Local structure of the Fe-doped La1−xCaxMnO3 (x=0.00-1.00) compounds has been investigated by means of Mössbauer spectroscopy. 57Fe Mössbauer spectra provide a direct evidence of Jahn-Teller distortion in these manganites. On the basis of Mössbauer results, the Jahn-Teller coupling was estimated. It is noteworthy that Ca-concentration dependence of Jahn-Teller coupling strength is very consiste...
متن کاملDirect Relationship between Magnetism and MnO6 Distortions in La12xCaxMnO3
Measured distortions of the Mn-O bond length distribution from x-ray-absorption fine-structure measurements are found to relate linearly to the doped hole concentration x at room temperature in La12xCaxMnO3. Comparison of the distortions above and below Tc for colossal magnetoresistor (CMR) samples gives an estimate of the number of delocalized holes ndh, and we find that lnsndhd ~ M (magnetiza...
متن کاملEvidence for two disparate spin dynamic regimes within Fe-substituted La0.7Pb0.3„Mn1−xFex...O3 (0ÏxÏ0.2) colossal magnetoresistive manganites: Neutron spin-echo measurements
The spin dynamics of substituted colossal magnetoresistive CMR manganites of general formula La0.7Pb0.3 Mn1−xFex O3, 0 x 0.2 is investigated by means of neutron spin-echo measurements. Substitution of Mn by Fe leads to a strong decrease of the temperature of macroscopic magnetic long-range ordering with a concomitant enhancement of the CMR effect. For x=0.2, a long-range-ordered state is not ac...
متن کاملMesoscopic thermodynamics of an inhomogeneous colossal-magnetoresistive phase
Equilibrium conductivity fluctuations of mesoscopic domains are found in film and bulk single-crystal manganite colossal magnetoresistive material. Temperature and field dependences of the Boltzmann factors for a collection of two-state fluctuators give measures of the magnetic moment and entropy differences between the states, and of the fluctuator volumes. The large resistance step size impli...
متن کامل