The effect of TiO2 doping on the structure and magnetic and magnetotransport properties of La0.75Sr0.25MnO3 composite

Abstract

The effect of TiO2 doping on the structure and magnetic and magnetotransport properties of La0.75Sr0.25MnO3 (LSMO)∕xTiO2 has been investigated. These studies show that at low doping level (x⩽2) TiO2 mainly goes into the grain-boundary region, but at high doping level (x⩾3), some part of the TiO2 goes into the perovskite lattice substituting Mn in LSMO and the remainder segregates as a separate phase at the grain boundaries. Results also show that the TiO2 doping has an important effect on a low-field magnetoresistance. In the magnetic field of 8000Oe and at 77K a magnetoresistance value of ∼20% was observed for the composite with a TiO2 doping level of x=2.

The effect of NiO doping on the structure, magnetic and magnetotransport properties of La0.8Sr0.2MnO3 composite

“…Several attempts have been made to enhance the LFMR effect of perovskite manganites by mixture of these CMR materials with secondary phases. They include LSMO/CeO 2 [15], LCMO/ZnO [16], LSMO/Al 2 O 3 [17] and LSMO/TiO 2 [18]. Also Coey et al [19] showed that by doping of half metallic ferromagnet CrO 2 with insulating antiferromagnetic Cr 2 O 3 enhances the LFMR.…”

Influence of grain size on magnetic and transport properties of polycrystalline La0.8Sr0.2MnO3 manganites

“…The application of moderate magnetic field can align the originally disordered Mn spins, thus reducing the scattering and leading to a LFMR. Several attempts have been made to enhance the LFMR effect of perovskite manganites: (1) making composites of these CMR materials with secondary phases [11][12][13][14][15] and (2) making powder compacts of materials with spin polarized charge carriers [16][17][18][19]. In the latter, the MR can be optimized by the adjustment of the microstructural characteristics, such as grain size.…”

Structural, magnetic and magnetotransport properties of La0.8Sr0.2MnO3/xLaMnO3 composites

“…Guinea [10] discussed the role of tunneling via paramagnetic impurity states in the grain boundary barrier. Several attempts have been made to enhance the LFMR effect of perovskite manganites by mixing these CMR materials with insulating second oxide and polymer phases [15][16][17][18][19][20]. Although the doping effects of nonmagnetic impurities on electrical transport of manganites have been investigated by several groups, the magnetic and magnetotransport behaviors of composites of magnetic insulator and CMR materials have rarely been investigated.…”