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The magnetization behaviors of two manganite oxide systems, La_0.7-xLn_xPb_0.3MnO₃ (Ln=PrandSm), have been synthesized. The replacement of La ions by Pr or Sm results in a considerable decrease in the ferromagnetic ordering temperature T_C and clearly irreversible behavior in the zero-field-cooling-field-cooling curve at a low applied field, showing a short-range spin order phase. These facts are in agreement with the smaller ionic radii of Pr (0.130 nm) and Sm (0.124 nm) ions in contrast to La ion (0.136 nm), and the corresponding larger distortion of perovskite structures. The saturation magnetization M_S decreases as Sm content increases relative to the increase of M_S as Pr content increases. This can be interpreted in terms of the competition between suppression of ferromagnetism due to structure tuning induced by the small ionic radius of the interpolated cations into the La-site and the increase of ferromagnetically interacting spins due to the introduction of magnetic Pr or Sm ions with f-shell electrons.

La_0.5Sr_0.5MnO₃ films on (001) LaAlO₃ were prepared by RF magnetron sputtering using powder target and were studied by SQUID and XPS. The XPS results show the formation of Mn³⁺ and Mn⁴⁺, indicating the coexistence of ferromagnetic (FM) and antiferromagnetic (AFM) clusters. SQUID measurement of LSMO on LAO and Si also support an interaction between them at low temperatures, resulting in the shift of hysteresis loops. Large coercivities at low temperature can be attributed to the pinning of both FM and AFM clusters and small coercivities at high temperature to the depinning of both FM and AFM phases, resulting from the thermal motion at higher temperatures which help to overcome the energy barrier and change the magnetic alignments.

We have investigated magnetization, magneto-transport, and complex impedance spectroscopy of structurally characterized multiferroic composites xLa_0.7Sr_0.3MnO₃ (LSMO)–(1-x)ErMnO₃ (EMO) (0≤x≤1). Para- to ferromagnetic Curie temperatures for this series of composites indicate almost complete immiscibility within the mixture of those two compounds of LSMO and EMO having nearly identical chemical formula. Magnetization as a function of magnetic field curves at T=300 K exhibit an appreciable enhancement of coercive field of LSMO in the composites with increase in EMO content. This feature has been attributed to the increasing grain boundary pinning center of LSMO grains at their interfaces in the composites. Magneto-transport measurements reveal a considerable decrease in spin polarized tunneling transport with increase in EMO content in the composites. This feature is understood as a consequence of increasing grain boundary pinning centers of magnetic domains of LSMO grains in the composites. Room temperature complex impedance spectroscopy studies, i.e., -Z^′′ versus Z′ curves (Nyquist plots) for EMO, x=0.1, x=0.2, and LSMO samples reveal that relaxation time of both bulk and grain boundary increases with increase in EMO content in the composites. Slow relaxation processes of conduction electrons at both bulk and grain boundary occurs due to the proximity of highly resistive insulating EMO in the composites.

Thin films and heterojunctions of Hf${}^{4+}$-doped LaMnO₃ manganite have been studied. The sole tetravalent state of Hf${}^{4+}$ ensures formation of $n$-type La${}_{1-x}$Hf${}_x$MnO₃ (LHMO) manganite. Photoinduced resistance was also observed as illuminated by visible light. The induced photoresistance (PR) could be greatly enhanced by the compressive strain. The LHMO/Nb-STO heterojunctions showed excellent rectifying characteristics, which are comparable with those $pn$-junctions of conventional semiconductors. Their transport properties are tunable electrically and magnetically. Such LHMO/Nb-STO heterojunctions have the potential to develop novel functional field-effect transistors based on manganite perovskites.

La${}_{0.9}$Hf${}_{0.1}$MnO₃ films were grown on 0.05 wt.% Nb-doped SrTiO₃ substrates by pulsed laser deposition. X-ray diffraction measurements demonstrated that our samples were of good epitaxy and single-crystal. The temperature-dependent resistance has been investigated. It was observed that the as-grown film of La${}_{0.9}$Hf${}_{0.1}$MnO₃ exhibited a typical paramagnetic-ferromagnetic transition. Heterojunctions of La${}_{0.9}$Hf${}_{0.1}$MnO₃/0.05 wt.% Nb-doped SrTiO₃ exhibited-asymmetric current–voltage characteristics and a remarkable temperature-dependent rectifying behavior in a wide temperature range (from 40 K to 300 K). And the most remarkable observation of this work is the existence of a crossover from positive to negative magnetoresistance in the La${}_{0.9}$Hf${}_{0.1}$MnO₃/0.05 wt.% Nb-doped SrTiO₃ heterojunction as the temperature decreases. A temperature-dependent magnetoresistance was studied as well. The rectifying characteristics and tunable magnetoresistance of these heterojunctions may be attributed to band structure of La${}_{0.9}$Hf${}_{0.1}$MnO₃/0.05 wt.% Nb-doped SrTiO₃ heterojunction.

Pr${}_{0.7}$Sr${}_{0.3}$MnO₃ thin films were grown epitaxially on SrTiO₃ and LaAlO₃ substrates by pulse laser deposition. X-ray diffraction spectra obtained on these films revealed good crystallinity and epitaxy. It was found that the oxygen deficiency and in-plane strain may affect the transport behavior and phase transition near Curie temperature in these Pr${}_{0.7}$Sr${}_{0.3}$MnO₃ films. Also, the resistance and metal-insulator phase transition could be modulated significantly by the applied electric currents. The reduction ratio of the peak resistance reached −38% for a bias current $I=500\mu$A, demonstrating a remarkable electroresistance effect. The results are interpreted based on the spatial inhomogeneity related to the coexisted multi-phases with different electronic and magnetic properties.

We synthesized the polycrystalline manganite of La_5/8Ca_3/8MnO₃ with three different manganese routes prepared through a solid state reaction method. The effects of the manganese route selection on the structure, electrical transport and magneto-transport properties were examined in this study. The samples were characterized using X-ray diffraction (XRD) and SEM to identify their structure and morphology. XRD analysis confirmed that all samples were in single phase with orthorhombic structure and belonged to the Pnma space group. The average grain sized samples with manganese route of Mn₂O₃ and MnCO₃ had a grain size of 1.2–8.7 μm and 2–7.5 μm, respectively. For the MnO₂ route, the sample had a small melt-like shape with higher porosity. The metal–insulator transition temperature, T_MI, for LCMO (Mn₂O₃), LCMO (MnO₂) and LCMO (MnCO₃) samples were 270 K, 266 K and 258 K, respectively. All the samples showed negative magneto-resistance with significant increase in value near the T_MI temperature. The highest CMR (colossal magneto-resistance) ratio was found in LCMO (Mn₂O₃), -22.06% at 270 K, followed by -16.69% for LCMO (MnO₂) at 80 K, and 15.2% for LCMO (MnCO₃) at 100 K in a 1 T magnetic field.

Strontium doped polycrystalline YMnO₃ multiferroic ceramics prepared by using conventional solid state reaction method are examined for their structural, thermodynamic and magnetic properties. The observed pointed kinks in the specific heat study are indicative of the probable coupling between the electric and magnetic orders in this class of materials. The reported systematic specific heat studies show that the antiferromagnetic (AFM) transition temperature (T_N) shifts to higher value with increasing concentration of Sr²⁺ ion in the YMnO₃. The reported compounds show the independence of specific heat behavior and magnetic transition temperature with applied magnetic field of 8 T and 12 T. Our systemic magnetization studies of "Sr" doped YMnO₃ compounds indicated a weak ferromagnetic characteristic in the temperature lower than the AFM transition temperature.

In this paper, we report the electron paramagnetic resonance (EPR) study of perovskite manganite Nd_0.55Sr_0.45MnO₃. Experimental data reveal that the EPR linewidth broadens with a quasilinear manner up to 480 K. The broadening of the EPR linewidth can be understood in terms of the shortening of carrier–lattice relaxation time due to the occurrence of strong carrier–phonon interactions. Two same activation energies obtained respectively from the temperature dependence of EPR intensity and resistivity indicate that the linewidth variation is correlated to the small polaron hopping. Therefore, the carrier–lattice coupling play a major role for deciding its magnetism in the present system.

In the scaling down of electronic devices, functional oxides with strongly correlated electron system provide advantages to conventional semiconductors. We report the fabrication of the electric double layer transistor (EDLT) with the (La,Pr,Ca)MnO₃ (LPCMO) epitaxial nanowall wire (NW) channel whose width was less than 100 nm. The width controlled LPCMO NWs were fabricated using an original nanofabrication technique: 3D nanotemplate pulsed laser deposition. The LPCMO NW EDLT was produced by employing 80 nm width NWs as channel. The produced LPCMO NW EDLT showed low leakage current. The metal-insulator transition property was successfully modulated by gating effect on the LPCMO NW EDLT.

The generation of spin current in materials with high spin–orbit coupling is one of the primary topics for future spintronic applications. In this context, the high conversion efficiency of spin current to charge current is desired. Ferromagnetic resonance (FMR)-based inverse spin Hall effect (ISHE) is a quite popular method to study such spin-to-charge conversion. Here microwave frequency plays a crucial role in generating spin current which further gets converted to charge current due to spin–orbit interaction of the given material. In this work, we show the effect of microwave frequency on spin-to-charge current conversion efficiency in La${}_{0.67}$Sr${}_{0.33}$MnO₃/Pt heterostructure prepared by oxygen-assisted molecular beam epitaxy (OMBE). From the ISHE analysis the maximum spin pumping voltage of ∼98 μV has been observed. Further spin Hall angle has been calculated for different frequencies and the maximum calculated value (∼0.06) for this system has been obtained at 14GHz.