Large magnetoresistance in polycrystalline La–Y–Ca–Mn–O

Abstract

A large magnetoresistance ratio in excess of 10 000% (at 140 K, H=6 T) has been obtained in a sintered perovskitelike material with a composition of La0.60Y0.07Ca0.33MnOx. The doping of La–Ca–Mn–O with Y resulted in a decrease in the lattice parameter by ∼0.2%, and improved the magnetoresistance by an order of magnitude. The fact that such a large magnetoresistance can be obtained in a polycrystalline material implies that an epitaxial film growth may not be necessary for device applications, with fewer restrictions in substrate selection and processing parameters. Low field measurements at 77 K gave a magnetoresistance ratio of ∼6.5% at H=500 Oe in the La–Y–Ca–Mn–O sample.

Local Structure of Mn in (La1-xHox)2/3Ca1/3MnO3Studied by X-ray Absorption Fine Structure

“…Also, the Mn-O-Mn bond angles decrease, which leads to weakening of the double exchange interaction and corresponds to decrease of the Curie temperature with increasing Ho content. The same conclusions were obtained in the cases, where the effect of substituting La for rare earth elements causes an increase of the orthorhombic distortion of the lattice, which leads to the decrease of the metal-insulator transition temperature [4,[8][9][10][11][12].…”

“…Mixed-valence manganites (La 1−x RE x ) 2/3 Ca 1/3 MnO 3 , where RE = Gd [8,9], Dy [10,11], Tb [4], * corresponding author; e-mail: pietnoczka@if.pw.edu.pl Y [9,12] were studied. The heavy rare earth elements substitution of La in (La 1−x RE x ) 2/3 Ca 1/3 MnO 3 causes a lattice distortion and introduces an disorder, which reduces the magnetic interaction.…”

Synthesis and characterization of Mn-, La-Mn- and La-Ca-Mn-citrates as precursors for LaMnO3 and La1−xCaxMnO3

“…These are based on the heating of mixtures of the oxides or the carbonates of the metals. As starting materials La 2 O 3 , MnO 2 [1], Mn 2 O 3 [2], Mn 3 O 4 [3], La 2 (CO 3 ) 3 , MnCO 3 , CaCO 3 [4] are used, heated for 5 -20 h at 1250 -1400…”

Magnetic correlations in a classic Mott system

“…For example, superconductivity occurs at a temperature as high as 133 K at ambient pressure in HgBa2CazCu3Os+a [l]. Colossal magnetoresistance, where the resistivity is reduced by 2 orders of magnitude in a magnetic field of 6 Tesla, is realized in (La,Y)MnOs [2]. In V203, the resistivity increases by 8 orders of magnitude at a metal-insulator transition [3].…”