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Magnetic characteristics, magnetocaloric effect, and critical behavior of Nd1−xSrxMnO3 compounds by Sr doping (x = 0.2, 0.3, 0.4, 0.5) were studied. All samples maintained orthorhombic structures, but the space group changed from Pnma (No. 62) for x = 0.2, 0.3 to Imma (No. 74) for x = 0.4, 0.5. As Sr doping increased, the Curie temperature (TC), Curie–Weiss temperature (TCW), and magnetization increased, attributed to the double exchange (DE) interaction. A discrepancy between TCW and TC was observed due to the competition between polarons and DE interaction. The critical behavior was investigated systematically using the self-consistent (modified Arrott plots, MAP) method and the Kouvel–Fisher (KF) relation. The KF relation was suitable for the samples with x = 0.2 and 0.5, while the MAP method was suitable for the samples with x = 0.3 and 0.4. Among the Ising, XY, Heisenberg, and mean-field models, the samples with x = 0.2, 0.3, and 0.4 aligned more closely with the mean-field model, except for the x = 0.5 sample. Entropy change (−ΔSM) of Nd1−xSrxMnO3 (0.2 ≤ x ≤ 0.5) increased with the applied field, with the maximum value observed around TC. For the sample with x = 0.3, (−ΔSM) reached 4.315 J/kg K at μ0ΔH = 50 kOe, corresponding to a relative cooling power (RCP) of 280.48 J/kg. Remarkably, the x = 0.4 sample displayed (−ΔSM) of 3.298 J/kg K at μ0ΔH = 50 kOe near room temperature, with the RCP of 283.64 J/kg. These findings underscore the role of Sr doping in tuning the magnetic properties, critical behavior, and magnetocaloric effect of NdMnO3. [ABSTRACT FROM AUTHOR]

The microstructure and magnetotransport of LaMnO3 manganite have been studied. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) at room temperature show that the LaMnO3 sample has a single-phase orthorhombic structure, and the sample particles and elements are densely and evenly distributed. By studying the temperature dependence of resistivity and magnetoresistance (MR), and the magnetic filed dependence of resistivity, it is found that the resistivity versus temperature curves of LaMnO3 show three extreme values in the temperature range of 10–390 K. Firstly, the minimum resistivity at about 70 K comes from the spin polarization tunneling effect. Secondly, there is a maximum resistivity near 189 K due to the inhomogeneity of the polycrystalline sample. Finally, the traditional metal to insulator (MI) transition leads to another maximum resistivity near 241 K, where the corresponding temperature is MI transition temperature (TMI). Moreover, the resistivity of LaMnO3 exhibits a decline as the external magnetic field being increased, implying the presence of MR. In the region of low temperature (close to the TMI), the negative MR reaches 14.68 and 45.28% under 1 T and 4 T applied fields, respectively. The coexistence of two kinds of MR mechanisms in LaMnO3 induced by spin polarization tunneling and Jahn–Teller distortion leads to the enhanced MR within the wide temperature range (10–265 K). [ABSTRACT FROM AUTHOR]

The magnetic properties, critical behavior, and magnetocaloric effect of perovskite NdMnO3 are studied. The Nd ordering is induced by the Mn ferromagnetic component with antiferromagnetic coupling with each other and then magnetization reversal occurs due to Mn moments reorientation induced by the ordering Nd moments, which explains the phenomenon of negative magnetization at low temperatures. The critical behavior of NdMnO3 is studied using Kouvel–Fisher and self-consistent methods. The results show that the Kouvel–Fisher method is reliable and critical exponents are coming out as β = 0.462 for TC = 11.15 K, γ = 1.041 for TC = 11.42 K, δ = 3.252 by critical isotherm analysis. Magnetic exchange distance may decay as J (r) ≈ r − 4.563 , that is, somewhere between the three-dimensional Heisenberg model and the mean field model. Remarkably, three temperature transitions and the corresponding three extremum values including positive and negative entropy change are observed in NdMnO3, which is different from previous reports on NdMnO3. A positive entropy change as 3.82 J/kg K at 10–15 K for μ0ΔH = 50 kOe and a negative entropy change as −0.557 J/kg K at around 8 K for μ0ΔH = 5 kOe are found, which can be put down to a fast magnetization change of NdMnO3 because of the Nd moments ordering and Mn moments reorientation. Besides, an entropy change of 1.22 J/kg K is found for μ0ΔH = 50 kOe at 80–85 K, which is corresponding to the Mn ferromagnetic ordering temperature. The relative cooling power of NdMnO3 reaches 105.9 J/kg, making it a promising candidate in the field of magnetic refrigeration. [ABSTRACT FROM AUTHOR]

Magnetoresistance and temperature coefficient of resistance (TCR) of manganites with ferromagnetism have been reported extensively, but the magnetoresistance and TCR of antiferromagnetic manganites are scarce. The transport properties, TCR, and magnetoresistance effect of antiferromagnetic NdMnO3 have been studied in this work. NdMnO3 samples exhibit semiconductor conductivity, and with the different applied magnetic fields, they still maintain semiconductor characteristics and have considerable stability. Under an applied magnetic field of 6 T, a small negative magnetoresistance of 8% appears near 150 K. Moreover, the conduction mechanism and TCR of NdMnO3 are studied. Three models, thermal activation (TA) model, small polaron (SP) model, and variable range jump (VRH) model, are used to analyze the electrical transport of NdMnO3 samples. The results show that the transport behavior of NdMnO3 samples is more consistent with the TA model. The maximum TCR is 9.4% K−1 within the low temperature region (above liquid nitrogen temperature). The TCR decreases with increasing temperature and it remains 2.5% K−1 near room temperature. Antiferromagnetic NdMnO3 has good TCR performance, which can be applied to temperature sensing field and has good application prospect in antiferromagnetic insulating electronic devices. [ABSTRACT FROM AUTHOR]

The evolution of the Griffiths phase (GP) with a ferromagnetic metal (FMM) cluster above the Curie temperature (TC) and its effect on the magnetic properties, electrical transport, magnetoresistance (MR), and magnetocaloric effect (MCE) is studied comprehensively, using bulk compounds of La1−xBaxMnO3 (0.15 ≤ x ≤ 0.25) with different lattice distortions but with the same structural symmetry and space group. These La1−xBaxMnO3 samples show ferromagnetic transition at TC increasing from 229 K for x = 0.15–300 K for x = 0.25, in addition to the presence of GP with FMM clusters in the paramagnetic (PM) region, which have been confirmed by the combination of magnetization (susceptibility) measurements, the GP theory, and electron paramagnetic resonance technology. With increasing the Ba2+ ion doping, GP temperature (TG) and TC of La1−xBaxMnO3 are increased, and the GP regime is strengthened. The GP ratio in the PM region reached 27.7% for the sample with x = 0.20. The resistivity decreases and the FMM phase increases with increasing x from 0.15 to 0.25, which can be explained by the decrease in the bandgap (Eg) and the enhancement of the double-exchange effect. Remarkably, large room-temperature MR (∼44.7%) can be observed in the sample with x = 0.25 under 60 kOe, which is related to the presence of the GP regime. Furthermore, the MCE is also affected by the GP regime, and it is deduced that the magnetic transition is of second order. The value of magnetic entropy change (| Δ S M |) reaches 3.04 J/kg K near room temperature for the sample with x = 0.25 under 50 kOe. This value is associated with a relative cooling power (RCP) of 248.1 J/kg. For the sample with x = 0.15, the value of RCP reaches 307.6 J/kg under 50 kOe. The discovery of the MR and MCE near room temperature is of great significance from the practical application of perovskite manganites in magnetic sensors and magnetic refrigerants. [ABSTRACT FROM AUTHOR]

The structure, magnetic, transport and magnetoresistance properties of SrMnO3 sample have been investigated. The SrMnO3 sample has single-phase structure with hexagonal symmetry, which is obtained by the X-ray diffraction. The scanning electron microscope reveals the particles of the sample are evenly distributed. The composition of the SrMnO3 sample is detected using the energy dispersive spectrometer, indicating the element ratio of Sr:Mn:O = 19.25:20.35:60.40. The magnetic, electrical transport and the magnetoresistance effect are studied via the temperature dependences of the magnetization, the resistivity and the magnetoresistance. An antiferromagnetic phase transition near 300 K appears in the SrMnO3 sample, and no significant entropy change can be found in the antiferromagnetic sample. The sample shows the insulator state since the resistance increases gradually with the decrease of temperature. Therefore, SrMnO3 is an antiferromagnetic insulator material. Moreover, the resistivity reduces significantly with the applied magnetic field, indicating an existence of magnetoresistance. Remarkably, the room-temperature magnetoresistance of the antiferromagnetic insulator SrMnO3 reaches 16.68% under 60 kOe field. This work opens our understanding of magneto-transport and magnetic properties of the antiferromagnetic SrMnO3. The discovery of magnetoresistance near room temperature in the antiferromagnetic insulator (SrMnO3) is of great significance for the development of antiferromagnetic spintronics. [ABSTRACT FROM AUTHOR]

The magnetocaloric and ferromagnetic properties of Pr0.7Sr0.3MnO3 film grown on (001) Pb(Mg1/3Nb2/3)0.7Ti0.3O3 (PMN-PT) using pulsed laser deposition technology have been investigated in this work. The X-ray diffraction measurement shows that the (001)-oriented film has been successfully deposited on PMN-PT substrate. The ferromagnetic properties and magnetocaloric effect resulted from ferromagnetic transition are explored via using the magnetic moment versus temperature plots, hysteresis loops, and the magnetic moment versus magnetic field curves. The magnetic moment versus temperature plots (M-T curves) show that with the decrease of temperature, the Pr0.7Sr0.3MnO3 film undergoes a transition from paramagnetic to ferromagnetic phase at temperature close to Curie–Weiss temperature (TCW). TCW (approximately 133 K) is determined by the Curie–Weiss law. The Pr0.7Sr0.3MnO3 film reveals the ferromagnetic feature below TCW, while the film exhibits the paramagnetic state at temperature higher than TCW. Hysteresis loops also confirm that the film reveals ferromagnetic feature at temperature lower than TCW (e.g. ferromagnetic behaviors at 10 and 100 K). The result of hysteresis loops is in accordance with the M-T curves. Besides, entropy change has been investigated in our work. The maximum entropy change of Pr0.7Sr0.3MnO3 film reaches about 2.4 J/kg·K at around TCW under 10 kOe field change, that is close to the entropy change of reference sample Gd (approximately 2.8 J/kg·K within the field change of 10 kOe), suggesting that the Pr0.7Sr0.3MnO3 film on PMN-PT has a great application prospect in magnetic refrigeration. [ABSTRACT FROM AUTHOR]

The magnetic properties were investigated for C- and P-implanted MgO single crystals, which were irradiated by 80 keV C and P ions with the dose of 3 × 1017 ions/cm2. The magnetic properties of pristine MgO were apparently changed by C and P ion implantation. Room temperature ferromagnetism was presented in the C-implanted sample, while the P-implanted sample only displayed paramagnetism at 20 K. For the purpose of clarifying the correlation between the magnetic properties and microstructure, a comparative study was carried out using experimental and theoretical methods in both C and P ion-implanted samples. The defect types were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, photoluminescence, and absorption spectrum. The existence of intrinsic (Mg vacancies, O vacancies) and extrinsic (C-related and P-related) defects were verified by the experimental results. The magnetic properties induced by various single and composite defects were studied by first-principle calculations. The calculation results indicated that the configuration of VMg (Mg vacancy) + CO (C substitute O defect) was a key factor for the inducing ferromagnetic properties in C-implanted MgO. For the case of the P-implanted MgO, the configuration of P-related defects and intrinsic vacancies can only contribute to the total moment value but cannot induce ferromagnetism. [ABSTRACT FROM AUTHOR]

The magnetic behaviors and magnetocaloric effect (MCE) of Pr0.7Sr0.3MnO3 (PSMO-7) film grown on a (001) SrTiO3 single-crystal substrate by a pulsed laser deposition (PLD) were studied in this paper. X-ray diffraction with a high resolution (HRXRD) measurement shows that PSMO-7 film is grown with a (001) single orientation. The magnetic properties and the MCE related to the ferromagnetic (FM) phase transition of the PSMO-7 film are investigated using the temperature dependence of magnetization M(T) and the magnetic field dependence of magnetization M(H). The M(T) data suggest that with decreasing temperatures, the PSMO-7 film goes through the transition from the paramagnetic (PM) state to the FM state at around the Curie temperature (TC). The TC (about 193 K) can be obtained by the linear fit of the Curie law. Magnetic hysteresis loop measurements show that the PSMO-7 film exhibits the FM feature at temperatures of 10, 100, and 150 K (low magnetic hysteresis can be found), while the film reveals the PM feature with the temperature increased up to 200 and/or 300 K. The research results of M(H) data are consistent with the M(T) data. Furthermore, the magnetic entropy change ( − Δ S M ) of the PSMO-7 film was studied. It was found that the maximum value of ( − Δ S M ) near TC reaches about 4.7 J/kg·K under the applied field change of 20 kOe, which is comparable to that of metal Gd ( − Δ S M of 2.8 J/kg K under 10 kOe), indicating the potential applications of PSMO-7 film in the field of magnetic refrigeration. [ABSTRACT FROM AUTHOR]

The transport properties and magnetoresistance (MR) effect of Pr0.7Sr0.3MnO3 (PSMO) film on SrTiO3 (STO) substrate are investigated in this work. The PSMO film is grown on (001) STO substrate by pulsed laser deposition (PLD). The high-resolution X-ray diffraction (XRD) pattern suggests that the Pr0.7Sr0.3MnO3 film shows the out-of-plane single orientation. Atomic force microscopy (AFM) image shows that the surface of the film is smooth. In addition, the significant interference peaks can be found in the XRD. All these confirm the high quality of the PSMO film grown on STO substrate to some extent. The magnetotransport properties and the MR associated to the double exchange (DE) interactions of the Pr0.7Sr0.3MnO3 film have been studied by the resistivity versus temperature and resistivity versus magnetic field data. The temperature dependence of resistivity shows that the film sample undergoes a metal-to-insulator (MI) transition at MI temperature TMI. The TMI gradually increases with the increase of applied magnetic field. Under different fields of 1 T, 2 T, 4 T and 6 T, the maximum values of negative MR (MR = [ρ-ρ0/ρ0] × 100%) reveal about 47.16%, 53.16%, 86.59% and 92.22%, respectively. Compared with other reports on bulk polycrystalline PSMO compounds and polycrystalline PSMO films, the PSMO film on STO in our work has relatively large MR, which is related to the single-oriented growth of PSMO/STO film. The large MR is conducive to the practical applications in magneto-electronic devices. The applied magnetic field dependence of resistivity shows that near TMI, the resistance changes significantly with the change of the applied field. This also implies that there is a large MR at around TMI, which can be explained by the traditional DE mechanism. [ABSTRACT FROM AUTHOR]

Samples of (110), (100), and (111) MgO single crystals were implanted with 70 keV N ions at room temperature. All as-implanted samples showed room temperature hysteresis in magnetization loops. The observed saturation magnetization (Ms) was 0.79 × 10−4 emu/g, 1.28 × 10−4 emu/g, and 1.5 × 10−4 emu/g for (110), (100) and (111) orientation implanted-MgO and follows the relation Ms(111) > Ms(100) > Ms(110), indicative of crystalline orientation-dependent ferromagnetism in N-implanted MgO. The samples were characterized by X-ray photoelectron spectroscopy (XPS), high resolution X-ray diffraction (HRXRD), reciprocal space mapping (RSM), and photoluminescence (PL). The results indicated that the amount of N-substitute-O and N-interstitial defects in these three N-implanted MgO samples showed the same changing tendency as compared with Ms data. Thus, we conclude that the N-substitute-O and N-interstitial defects may play a crucial role in controlling the N+-implanted-induced ferromagnetism. [ABSTRACT FROM AUTHOR]

The magnetic properties and exchange bias (EB) effect of perovskite NdMnO3 ceramic are studied in this work. In A-type antiferromagnetic (AFM) NdMnO3, the ordering of Nd3+ is caused by Mn3+ ferromagnetic component with antiferromagnetic coupling with each other. Interestingly, the Nd3+ ordering induces the Mn3+ spin reorientation, which explains the phenomenon of the negative magnetization at low temperature. The magnetic ordering of Nd3+ and Mn3+ ions is decisive to the EB effect. Remarkably, the positive EB effect is observed at 40 and 25 K, and both positive and negative EB effects are found at 5 K. These EB effects are relied on the cooling fields. The EB can be determined by the initial states and the coupling of Nd3+ ordering and Mn3+ ordering. The present work shows the role of magnetic ordering of Nd3+ and Mn3+ ions in regulating the EB and magnetic properties of perovskite NdMnO3. [ABSTRACT FROM AUTHOR]

The nanostructures usually possess plenty of surface traps owing to their large surface-ratio comparing with the corresponding bulk materials. Hence understanding the carrier transport related to the traps is critical to enhance the performance of the nanostructures. Here, based on the studies to Meyer–Neldel relationship, a phenomenon closely related to the traps and widely observed in various materials, we reveal the broad distribution nature of the trap in the nested nano-networks of Bi2S3, and accordingly design the improved strategy to enhance its switching performances based on trapping/detrapping of the charge carriers in Bi2S3 nested nano-networks. It achieves improved optical switching time from few hundred seconds to few seconds by using only the shallow traps. While thanks for their deep traps, it could produce multi-level resistive switching with optimal on/off ratio better than 50. [ABSTRACT FROM AUTHOR]

The influence of biaxial strain on both the electronic and magnetic properties in double perovskite La2FeMnO6 is investigated by using density-functional calculations. The results show that La2FeMnO6 exhibits ferromagnetic semiconductor at ambient condition and turns into ferromagnetic half-metal under the whole tensile strain applied in this work, while the compound transfers into ferromagnetic metal under the compressive strain within -8% and into ferrimagnetic semiconductor with the compressive strain beyond -9%. For both ferromagnetic half-metallic and metallic La2FeMnO6, they exhibit very slight change in the electronic states and magnetic moments of the ions, comparing with those of the compound at ambient condition. The electronic configurations of Fe and Mn originating from the high-spin state Fe3+ and intermediate-spin state Mn3+ in ferromagnetic La2FeMnO6 emerge in the low-spin state and high-spin state in ferrimagnetic La2FeMnO6, respectively, when the compressive strain is beyond -9%. [ABSTRACT FROM AUTHOR]

Magnetic anisotropy plays an important role in the development of manganite-based magnetic devices. Establishing a deeper understanding of the anisotropy in manganites is useful for controlling their magnetic properties. We have studied the structure, lattice strain, and magnetic properties of La0.5Ba0.5MnO3 (LBMO-5) films with the thickness of 12 nm–96 nm, grown on the (001) SrTiO3 (STO) substrate. The LBMO-5 films are grown with high crystalline quality. The orientation relationship between the LBMO-5 film and the STO substrate [(001)f//(001)s, (010)f//(010)s, and (100)f//(100)s] exists at the film/substrate interface. With increasing the thickness of the film to 48 nm, the LBMO-5 film is fully strain relaxed. The LBMO-5 film shows the out-of-plane magnetic anisotropy (OMA) along the three mutually perpendicular crystalline axis directions. Usually, the manganite films with tetragonal distortion show both the OMA and the in-plane magnetic isotropy. However, the in-plane magnetic anisotropy (IMA) along the two mutually perpendicular in-plane directions ([010]f and [100]f) is clearly observed in LBMO-5 films. We attribute this new observation of the IMA to the in-plane structural anisotropy along the two distinct crystalline axes. Our studies provide helpful guidance for the understanding and the tuning of the IMA. [ABSTRACT FROM AUTHOR]

Half-doped perovskite Manganese oxide has been widely studied because of its excellent properties such as colossal magnetoresistance (CMR) effect and charge-ordered (CO) phase separation. In this work, four Sm0.5Ca0.5MnO3 samples with different particle sizes are prepared by high-temperature solid-state reaction and ball milling. The crystal structure of the samples is studied by X-ray diffraction (XRD). The Sm0.5Ca0.5MnO3 sample is single phase, which belongs to orthorhombic structure. The surface morphology and particle size of the samples are examined by scanning electron microscope (SEM). The average particle size of the sample without ball milling is about 4 μm. With ball milling time for 12 h, 24 h, and 36 h, the particle size decreases, and finally it reaches hundreds to tens of nanometers. This shows that ball milling is an effective way to control the particle size. The M–T curves and M–H hysteresis loops of the samples are measured by physical properties measurements systems (PPMS). The two M–T curves measured in the warming and cooling processes do not overlap for Sm0.5Ca0.5MnO3 without ball milling, and the phenomenon of thermal hysteresis appears. Meanwhile, the M–T curve has a significant protuberance peak near 270 K. All of these indicate the CO behavior, whereas the particle size of Sm0.5Ca0.5MnO3 decreases with different milling times (12–36 h) and the CO phase is suppressed gradually, which leads to the decrease of CO temperature, magnetization, remanence, and coercivity. [ABSTRACT FROM AUTHOR]

Sm3+-Modified (1 − x)Na0.5Bi0.5TiO3-xCaTiO3 (NBT-xCT:Sm3+) piezo-luminescent ceramic materials were synthesized to investigate the influence of CaTiO3 (CT) concentration on their photoluminescence and electrical performance. Under 480 nm irradiation, the NBT-xCT:Sm3+ samples exhibit prominent orange-red emission, with a prime emission peak centered at 597 nm. A moderate amount of CT doping in the Sm3+-modified NBT ceramics boosts both their photoluminescence and piezoelectric properties significantly, with NBT-0.04CT:Sm3+ showing the optimal performance. Furthermore, outstanding luminescence thermal stability over a temperature range of 293–473 K and superior water resistance behavior are achieved in the NBT-0.04CT:Sm3+ ceramic. These results indicate that NBT-xCT:Sm3+ piezo-luminescent ceramics show great potential applications in white LEDs, as well as novel optical-electronic multifunctional devices. [ABSTRACT FROM AUTHOR]

The high-pressure effect on the physical properties in double perovskite Sr2FeMoO6 is explored theoretically. The structure of Sr2FeMoO6 exhibits I4/mmm symmetry in the whole external hydrostatic pressure applied. A spin crossover of Fe ion from high-spin to low-spin state is found at the pressure of about 33-36 GPa, accompanied by a transition from ferrimagnetic half-metallic to nonmagnetic semiconductor state. When the pressure is above 45 GPa, the nonmagnetic compound behaves as full metal. By the mean-field theory, the estimated Curie temperature of the ferrimagnetic Sr2FeMoO6 increases from 472 to 639 K when the pressure increases from 0 to 30 GPa. [ABSTRACT FROM AUTHOR]

Using density-functional calculations within the generalized gradient approximation plus U framework, the electronic and magnetic properties of the ordered and the disordered Sr2FeCoO6 are investigated systematically. The results show that all disordered Sr2FeCoO6 have ferromagnetic ground state, as that of the ordered one. The magnetic coupling of both Fe and Co sublattices remains ferromagnetic, and the two sublattices are coupled ferromagnetically as well. Most interestingly, the disorder leads to the substantial increase of the magnetic moments on both Fe and Co sites comparing with those of the ordered Sr2FeCoO6. It is also significantly found that the disorder can control the transport property, decreasing the half-metallic band gap of the ordered Sr2FeCoO6 and even giving rise to a half-metal to metal transition at a critical level of disorder. [ABSTRACT FROM AUTHOR]

In this work, we report the attractive magnetic properties of La1-xCaxMnO3 manganites with x = 0.2 (LCMO-2) and x = 0.5 (LCMO-5). X-ray diffraction (XRD) measurements show that the prepared samples are single phase and they crystallize in the orthorhombic structure with Pnma space group. Scanning electron microscope (SEM) measurements reveal that the particles of samples are homogeneous and possess the diameter of several microns. Magnetization versus temperature measurements show paramagnetic (PM) to ferromagnetic (FM) transition at TC ≈ 200 K for LCMO-2 and at TC ≈ 250 K for LCMO-5. Below TC, FM nature is observed in LCMO-2. However, LCMO-5 displays the complex magnetic phase transition. Below TC, LCMO-5 shows a FM to charge-ordered antiferromagnetic (COAFM) transition at CO temperature TCO and a novel, unexpected FM phase transition at characteristic temperature T* (near 35 K). The FM and COAFM phases coexist in LCMO-5, and the competition of FM and AFM phases lead to the unexpected FM transition at T*. Furthermore, the inverse of susceptibility versus temperature measurements confirm the similar results. Magnetic hysteresis loop measurements suggest the typical FM feature of LCMO-2. However, LCMO-5 exhibits the hysteresis loops with butterfly-type structure at 100 and 150 K, suggesting the presence of COAFM phase. These attractive magnetic properties are explained by the existence of COAFM phase and the competition between FM and COAFM phases. [ABSTRACT FROM AUTHOR]

The structural and magnetic properties of Y2−xSrxCoMnO6 (0 ≤ x ≤ 0.5) compounds are investigated in this report. X-ray photoelectron spectroscopy reveals that Co and Mn ions are presented in the form of Co2+/Co3+ and Mn3+/Mn4+, respectively. The broadening of Raman spectra suggests the existence of antisite disorders in these double perovskite oxides. The ferromagnetic transition temperature slightly increases with Sr doping, while the saturated magnetic moment shows a substantial decrease, further confirming the presence of Co/Mn antisite disorders. The signature of exchange bias effect in Y2−xSrxCoMnO6 (0 ≤ x ≤ 0.5) double perovskites has been observed, which is demonstrated by the displacement of field-cooled magnetic hysteresis loops. Moreover, the exchange bias field is strongly correlated with the degree of antisite disorders and reaches a maximum of 3.4 kOe for x = 0.25. The origin of exchange bias effect can be explained as the interfacial exchange coupling between ferromagnetic regions and antiferromagnetic antiphase boundaries created by antisite disorders in these specimens. [ABSTRACT FROM AUTHOR]

PrSrMnO (PSMO) films were fabricated on (0001) sapphire substrates by pulsed laser deposition. The structure and transport properties of the films have been investigated. Several textures and disorder coexist in the PSMO films and result in the colossal magnetoresistance (MR) effect at a wide temperature range of 5-210 K. Colossal MR at the wide temperature region provides opportunities for practical application in manganite film devices. Our research results demonstrate that the textures and the disorder state induced by multiple growth orientations can strongly influence the transport properties of film. [ABSTRACT FROM AUTHOR]

We have grown PrSrMnO/LaCaMnO bilayer on (001) single crystal SrTiO substrate by pulsed laser deposition technique. The bilayer film is well (001) orientation grown with high crystalline quality. When the applied magnetic field increases up to 9 T, only metal-like transport behavior can be observed below room temperature. The Low-field MR (LFMR) as large as ~−73% has been achieved at an applied field of 1 T and the magnetoresistance (MR) can reach a value of ~−641% at an applied field of 9 T. Ferromagnetic (FM) clusters percolation accompanied with the collapse (melting) of charge-ordered (CO) state in LaCaMnO may be responsible for the enhancement of MR. Moreover, the disappearance of exchange bias (EB) in the bilayer demonstrates the existence of FM clusters percolation at the PSMO/LCMO interface. Large LFMR provides possibilities in developing manganite-based FM/CO film devices. [ABSTRACT FROM AUTHOR]

The phase transitions of melt-spun Ni50Mn35In15 ribbons are modulated with post-annealing. Both the martensitic transformation temperatures and Curie temperature of the austenitic phase increase after post-annealings. However, the maxima of phase transition temperatures are obtained after 873 K annealing, instead of higher-temperature annealings. The nonmonotonic dependences exclude Mn volatilization and grain growth from the dominant reason. The superlattice reflections in Heusler structure indicate that the increases of phase transition temperatures should be related to the increment of L21 atomic order. [ABSTRACT FROM AUTHOR]

The effect of S-doping on the properties of double perovskite La2FeMoO6 (LFMO) is investigated by using density-functional calculations. The results reveal that the ground state of the series La2FeMoO6-xSx is ferrimagnetic, with I4/mmm symmetry for x = 0 and 6, and I4mm symmetry for the others. With increasing the amount of S ions, the volume increases nearly linearly. The estimated Néel temperature of the compounds decreases from 537 K for La2FeMoO6 to 454 K for La2FeMoS6 upon S doping. In addition, La2FeMoO6 and the end member La2FeMoS6 both exhibit half-metallic nature, while the others behave as full metal. [ABSTRACT FROM AUTHOR]

Abstract: Using density-functional calculations, we investigate the special properties of SrFe1−x Co x O3. The results show that the ground states have A-type antiferromagnetic order for and ferromagnetic order for with Co ions distributed averagely. SrFe1−x Co x O3 exhibits half-metallic nature for and full-metallic nature for other values of , and the half-metallic gap decreases with increasing . The tunneling between the half-metallic ferromagnetic phases drives the large magnetoresistance. In addition, the Co cations are in the intermediate-spin state, while the Fe cations are in the intermediate-spin state for and the high-spin state for . [Copyright &y& Elsevier]