Effects of iron doping on the transport and magnetic behaviour in La_0.65Ca_0.35Mn_1-yFe_yO₃

Abstract

We report on the magnetic and transport measurements in an Fe-doped colossal magnetoresistance compound (La 0.65 Ca 0.35 MnO 3 ). Increased spin disorder and a decrease of T c with increasing Fe content are evident. We find that the resistivity data above T p fits better to a variable range hopping model and the localization length decreases with Fe content. The variations in the critical temperature T c , confinement length, magnetic moment and magnetoresistance show a rapid change at about 4-5% Fe. The maximum magnetoresistance is seen to increase consistently with the addition of Fe and increases up to 400% for 8% Fe. The effect of Fe is seen to be consistent with the disruption of the Mn-Mn exchange, possibly due to the formation of magnetic clusters.

Re-entrant spin freezing behavior in La0.85Ca0.15Mn0.95Fe0.05O3 manganite

“…relatively stronger antiferromagnetic superexchange effects. It is noticeable for this particular host composition that the addition of 5% Fe results in a decrease of the critical temperature by only 40 K. For the same Fe ion concentration the T c decreases by over 90 K for the La 0.65 Ca 0.35 MnO 3 composition [18]. However no spin glass state is observed in the latter down to 77 K. This difference in behavior is most probably due to the optimum Mn 3+ -Mn 4+ composition in the La 0.65 Ca 0.35 MnO 3 composition, which is very sensitive to the depletion of the Mn 4+ -Mn 3+ bonds as caused by the Fe.…”

“…We have previously observed [18] that in the strongly ferromagnetic La 0.70 Ca 0.30 MnO 3 (70-30) composition the ferromagnetic T c is suppressed at about 19 K/Fe% in the range 1-10% of Fe. This is well understood [17] in terms of the increased antiferromagnetism due to the Fe 3+ ions and the reduction in the number of Mn 4+ ions, as a consequence of the Fe addition.…”

“…The role of Fe in the manganites is ideal since it is known to substitute primarily in the Fe 3+ state and to interact anti-ferromagnetically with the Mn [17]. Our previous studies [18] on Fe doping have been in the optimally doped (xB0:33) compositions that are strongly ferromagnetic and showed a decrease of T c but no development of the spin glass state down to T ¼ 77 K for doping levels up to 10% Fe. We have studied the development of magnetic order in the composition La 0.85-Ca 0.15 Mn 0.95 Fe 0.05 O 3 that lies close to the AFM-FM phase boundary and to the A-type antiferromagnetic ordering.…”

Magnetic properties and colossal magnetoresistance of La5/6Na1/6Mn1−yFeyO3 with 0≤y≤0.10

“…With the density of states N (E) = 9 × 10 26 m 3 ev −1 (Ref. 25) and T 0 , it is found that the localization length decreases from ξ ≈ 0.066 nm for y = 0, ξ ≈ 0.021 nm for y = 0.05 and ξ ≈ 0.005 nm for y = 0.10, which indicates the increase of the charge-carrier localization intensity. It also indicates that double exchange interaction decreases with the increase of the Fedoping level, possibly due to the formation of magnetic cluster.…”

Growth and properties of pulsed laser deposited Fe3O4/La0.7Ca0.3MnO3 bilayers

“…It is interesting to observe the effect of Fe 3 O 4 layer on the LCMO system at the junction. As temperature is lowered from room temperature, electron finds the LCMO as a low resistance path therefore, LCMO behavior dominates and shows transition-like feature near 150 K. It is to be recalled that Fe doped LCMO system also shifts transition to the lower temperature side [13]. Nevertheless, the oxygen loss from LCMO also cannot be ruled out as the growth of Fe 3 O 4 is taking place at relatively lower oxygen partial pressure than the LCMO film.…”