Ferromagnetic Double-exchange Interaction Research Articles

Melting of the charge-ordered state in Y0.5Ca0.5MnO3 through Ru-substitution and consequent development of ferromagnetic and magnetocaloric behavior

The effect of Ru-substitution (5–15 %) on the charge ordering of Y0.5Ca0.5MnO3 has been investigated in this paper. Ru, existing in different oxidation states such as Ru4+ and Ru5+, plays an immense role in causing ferromagnetic (FM) superexchange interactions with Mn3+ ions. This, combined with the FM double-exchange interactions between Mn3+ and Mn4+ ions, destroys charge ordering. The development of ferromagnetism in Ru-substituted compounds is understood experimentally through the remarkable enhancement of dc magnetization with a simultaneous shift of TC from 57 K to 95 K with increasing Ru content from x = 0.05 to x = 0.15. The appearance of hysteresis for higher doping concentrations further confirms the FM nature. Concomitant with the favorable impact on the magnetic nature, there is also a development of magnetocaloric properties upon Ru-substitution. The maximum magnetic entropy change for x = 0.05 to 0.15 that was found to peak at TC ranges from 1.08 J/kg/K to 2.8 J/kg/K respectively for a field change of 9 T. The corresponding relative cooling power (RCP) increases from 76 J/kg to 324 J/kg indicating a significant growth of RCP with Ru substitution. These salient features of Ru-doped Y0.5Ca0.5MnO3 would make it a suitable candidate for magnetic refrigeration.

Colossal Magnetoresistive Switching Induced by d0 Ferromagnetism of MgO in a Semiconductor Nanochannel Device with Ferromagnetic Fe/MgO Electrodes.

Exploring potential spintronic functionalities in resistive switching (RS) devices is of great interest for creating new applications, such as multifunctional resistive random-access memory and novel neuromorphic computing devices. In particular, the importance of the spin-triplet state of cation vacancies in oxide materials, which is induced by localized and strong O-2p on-site Coulomb interactions, in RS devices has been overlooked. d0 ferromagnetism sometimes appears due to the spin-triplet state and ferromagnetic Zener's double exchange interactions between cation vacancies, which are occasionally strong enough to make nonmagnetic oxides ferromagnetic. Here, for the first time, anomalous and colossal magneto-RS (CMRS) with very high magnetic field dependence is demonstrated by utilizing an unconventional RS device composed of a Ge nanochannel with all-epitaxial single-crystalline Fe/MgO electrodes. The device shows colossal and unusual behavior as the threshold voltage and ON/OFF ratio strongly depend on a magnetic field, which is controllable with an applied voltage. This new phenomenon is attributed to the formation of d0 -ferromagnetic filaments by attractive Mg vacancies due to the spin-triplet states with ferromagnetic double exchange interactions and the ferromagnetic proximity effect of Fe on MgO. The findings will allow the development of energy-efficient CMRS devices with multifield susceptibility.

Cationic mismatch effect on structural and magnetic behavior of La0.5-xEuxCa0.5-yBayMnO3 charge-ordered manganites

In this research, we have tried to investigate the effect of the cationic disorder on charge ordering and magnetic phase separation in La0.5-xEuxCa0.5-yBayMnO3 (x = 0, 0.05, and 0.1) compounds synthesized by using the sol-gel method. All the samples possess the same average ionic radius at A site <rA> and the same Mn3+/Mn4+ ratio. Our analysis confirmed the chemical composition by energy dispersive X-ray spectroscopy and verified the structural integrity and purity of the phase by X-ray diffraction, revealing an orthorhombic structure with Pnma space group, which is in agreement with the tolerance factor. The important mismatch effect observed in the substituted specimens induces drastic effects on the structural and microstructural properties. Magnetic measurements indicate a great reduction of Curie temperature for substituted samples (from 250 K for x = 0 to 90 K for x = 0.05 and 85 K for x = 0.1), which indicates a weakening of ferromagnetic double exchange interactions induced by cationic disorder. The Arrott plots and the magnetocaloric study of the Eu−based samples indicate the persistence of the antiferromagnetic charge-ordered state characterizing the pristine compound (x = 0) as well as the presence of a first-ordered metamagnetic transition for all the studied samples, which is ascribed to the presence of antiferromagnetic domains. Such transition induced the appearance of a shoulder peak near 100 K in the magnetic entropy change curves for high magnetic field values, resulting in an extra cooling efficiency.

Effect of Cr substitution on structural, magnetic, magnetocaloric and critical behaviors of La0.7Y0.05Ba0.25MnO3 perovskite manganite

A thorough investigation was conducted into the structural, magnetic, and critical properties of La0.7Y0.05Ba0.25Mn1-xCrxO3 (x = 0 and 0.15) perovskite manganite synthesized using the sol-gel method. The samples possess an orthorhombic structure with the Pnma space group according to X-ray diffraction (XRD) patterns. The average ion radii of the B-site cation (<rB>), the unit cell volume (V), and <θMn,Cr–O–Mn,Cr > bond angle decreased with Cr substitution. While the average bond distance, <dMn,Cr–O>, and Goldschmidt tolerance factor (tG) increased. The samples present a magnetic transition from a paramagnetic (PM) phase to a ferromagnetic (FM) phase at Curie temperature (TC). Addition of Cr to La0.7Y0.05Ba0.25MnO3 decreased the TC value from 310 K (for x = 0 sample) to 258 K (for x = 0.15 sample). Using Banerjee's criteria, second-order phase transitions were determined for the samples. Both samples showed significant maximum entropy change |ΔSMmax| and relative cooling power (RCP) whose values decreased from (6.40 J Kg−1 K−1 and 231 J Kg−1 for x = 0) to (4.45 J Kg−1 K−1 and 185 J Kg−1 for x = 0.15), respectively. These values indicate that the La0.7Y0.05Ba0.25Mn1-xCrxO3 manganites exhibit favourable magnetocaloric effect (MCE) and demonstrate promising potential for application as materials in magnetic refrigeration technology. The estimated critical exponents (β, γ, and δ) for the x = 0 sample align with the 3D-Ising model, while for x = 0.15, they closely resemble the 3D-Heisenberg model. This shift in the universality class can be attributed to the interplay between competing ferromagnetic double-exchange and antiferromagnetic super-exchange interactions that exist within the prepared samples.

Effect of A-site ionic disorder on structure, magnetic and magnetocaloric properties of La0.85-xNdxAg0.15-yKyMnO3 manganites

In this paper, the effect of A-site ionic disorder (σ2) on the structure, magnetic and magnetocaloric properties in La0.85-xNdxAg0.15-yKyMnO3 have been investigated. X-ray diffraction analysis using Rietveld refinement shows that the crystal structure of the perovskite manganites changes from rhombohedral (space group R3 ͞C) to orthorhombic (space group Pnma) structure with the increasing in σ2. Magnetization measurements showed that, upon increasing σ2, ferromagnetic double exchange interaction of the perovskite manganites diminishes, and as a result, Curie temperature (TC) of the samples decrease linearly. The inverse of susceptibility shows a downturn with decreasing temperature before TC indicating the existence of the Griffiths phase for La0.62Nd0.23Ag0·099K0·051MnO3 (σ2 = 0.004). The magnetic phase transitions of all the samples are belongs to second order transition.

Effect of Chromium Substitution on Microstructure and Magnetic Properties of La&lt;sub&gt;0.7&lt;/sub&gt;Sr&lt;sub&gt;0.2&lt;/sub&gt;Ba&lt;sub&gt;0.1&lt;/sub&gt;Mn&lt;sub&gt;1-&lt;/sub&gt;&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt;Cr&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt;O&lt;sub&gt;3&lt;/sub&gt; (&lt;i&gt;x&lt;/i&gt; = 0, 0.03, 0.05, 0.07, 0.1)

Structure, morphology, and magnetic properties of perovskite La0.7Sr0.2Ba0.1Mn1-xCrxO3 (x = 0; 0.03; 0.05; 0.07 and 0.1) synthesized via sol-gel method have been studied. X-ray diffraction studies confirm the Rhombohedral structure with R-3c space groups for all samples. The magnetization measurements clearly show that magnetization decreases with increasing Cr substitution concentration. The partial substitution of Cr3+ in the Mn site weakens the ferromagnetic double exchange interaction of the Mn3+–O–Mn4+ bond. It is caused by the emergence of the Cr3+–O–Cr3+ antiferromagnetic interaction. As known, the structural parameters affect the magnetic properties of perovskite manganese materials in the double exchange interaction. As the Cr3+ concentration increases, the average Mn-O bond length also increases, and the average Mn-O-Mn bond angle decreases, which dramatically weakens the Mn3+–O–Mn4+ double exchange interaction.

Evolution of complex magnetic phases and metal-insulator transition through Nb substitution in La0.5Sr0.5Co1−xNbxO3

We report the evolution of structural, magnetic, transport, and electronic properties of bulk polycrystalline ${\mathrm{La}}_{0.5}{\mathrm{Sr}}_{0.5}{\mathrm{Co}}_{1\ensuremath{-}x}{\mathrm{Nb}}_{x}{\mathrm{O}}_{3}$ ($x=$ 0.025--0.25) samples. The Rietveld refinement of the x-ray diffraction patterns with $R\overline{3}c$ space group reveals that the lattice parameters and rhombohedral distortion monotonously increase with the ${\mathrm{Nb}}^{5+}(4{d}^{0}$) substitution ($x$). The magnetic susceptibility exhibits a decrease in the magnetic ordering temperature and net magnetization with $x$, which manifests that the Nb substitution dilutes the ferromagnetic (FM) double-exchange interaction and enhances the antiferromagnetic (AFM) superexchange interaction. Interestingly, for the $x&gt;$ 0.1 samples the FM order is completely suppressed and the emergence of a glassy state is clearly evident. Moreover, the decrease in the coercivity (${H}_{C}$) and remanence (${M}_{r}$) with $x$ in the magnetic isotherms measured at 5 K further confirms the dominance of AFM interactions and reduction of FM volume fraction for the $x&gt;$ 0.1 samples. More interestingly, we observe resistivity minima for the $x=$ 0.025 and 0.05 samples, which are analyzed using the quantum corrections in the conductivity, and found that the weak localization effect dominates over the renormalized electron-electron interactions in the three-dimensional (3D) limit. Further, a semiconducting resistivity behavior is obtained for $x&gt;$ 0.05, which follows the Arrhenius law at high temperatures ($\ensuremath{\sim}160$--320 K), and the 3D variable range hopping prevails in the low-temperature region ($&lt;160$ K). The core-level photoemission spectra confirm the valence state of constituent elements and the absence of ${\mathrm{Co}}^{2+}$ is discernible.

High entropy effect on double exchange interaction and charge ordering in half doped Nd0.5Sr0.5MnO3 manganite

The entropy stabilized oxides i.e., the so-called high-entropy oxides are of great interest in recent time due to their intriguing physical properties. This new category of advanced materials is stabilized by the high configurational entropy of randomly mixed elements, where a specific lattice site is populated by five or more elements. The present study is devoted to explore the high entropy effect in well-known charge ordered manganite Nd0.5Sr0.5MnO3 where a delicate balance exists between the ferromagnetic double exchange and the antiferromagnetic superexchange interactions. Powder X-ray diffraction analyses confirm phase purity of the samples. FE-SEM imaging revealed the microstructure and elemental mapping confirmed the chemical homogeneity of the samples as well as nominal cationic composition. Bond valence sum (BVS) calculation using refinement parameters supports the expected cationic valence in all the samples. Replacement of Nd3+ by five trivalent cations as in (La0.1Pr0.1Nd0.1Gd0.1Bi0.1)Sr0.5MnO3 with larger average A-site ionic radius,<rA>and smaller size variance, σ2 compared with Nd0.5Sr0.5MnO3 dramatically suppressed the ferromagnetic double exchange interaction. This observation is in contrast with the expected variation in<rA>and σ2. In (La0.1Nd0.1Gd0.1Bi0.1Y0.1)Sr0.5MnO3 with smaller<rA> and marginally higher σ2 the ferromagnetic state ceases to exist. In both the multicationic compositions, a long-range antiferromagnetic state is evolved around 200 K with the retention of charge ordering. In the high entropy (La1/6Nd1/6Dy1/6Ca1/6Ba1/6Sr1/6)MnO3 composition with nominal<rA> and larger σ2 values the high temperature long-range ordering is completely suppressed and a new antiferromagnetic state is evolved at 45 K without manifestation of any charge ordering. This composition also avoids magnetic frustration unlike the dopant variant with larger σ2. The present investigation thus highlights the role of local lattice distortion or high entropy effect apart from the<rA>and σ2 in manganites.

Superior oxygen evolution reaction performance of NiCoFe spinel oxide nanowires in situ grown on β-Ni(OH)2 nanosheet-decorated Ni foam: case studies on stoichiometric and off-stoichiometric oxides

This work proposes a new direction towards rational design of highly efficient NiCoFe oxide based OER electrocatalysts where induced oxygen vacancies and enhanced ferromagnetic double exchange interactions resulted in the favourable configuration.

Ferromagnetism of MnO anchored on graphene with N dopant

MnO is a well-known antiferromagnetic transition mental oxide with a wide band gap, the lack of intrinsic ferromagnetism limits its applications in spintronics. Hence, in order to expand the application field of MnO and especially explore the existence of ferromagnetism, we experimentally achieve the N-doped MnO anchored graphene. As is expected, the MnO-based samples exhibit obvious intrinsic room temperature ferromagnetism, which is dependent on the N dopant concentration. Further, density functional theory (DFT) results reveal that the spontaneous magnetization comes from the ferromagnetic double-exchange interaction between Mn atoms with the aid of N dopants.

Ru-Doping-Induced Spin Frustration and Enhancement of the Room-Temperature Anomalous Hall Effect in La2/3 Sr1/3 MnO3 Films.

In transition-metal-oxide heterostructures, the anomalous Hall effect (AHE) is a powerful tool for detecting the magnetic state and revealing intriguing interfacial magnetic orderings. However, achieving a larger AHE at room temperature in oxide heterostructures is still challenging due to the dilemma of mutually strong spin-orbit coupling and magnetic exchange interactions. Here, Ru-doping-enhanced AHE in La2/3 Sr1/3 Mn1-x Rux O3 epitaxial films is exploited. As the B-site Ru doping level increases up to 20%, the anomalous Hall resistivity at room temperature can be enhanced from nΩ cm to µΩcm scale. Ru doping leads to strong competition between the ferromagnetic double-exchange interaction and the antiferromagnetic superexchange interaction. The resultant spin frustration and spin-glass state facilitate a strong skew-scattering process, thus significantly enhancing the extrinsic AHE. The findings can pave a feasible approach for boosting the controllability and reliability of oxide-based spintronic devices.

Polarity and charge redistribution induced emergent interfacial ferromagnetism in non-magnetic LaNiO3/SrMnO3 superlattices

Artificial heterostructures composed of strongly correlated oxides can host many up-and-coming phenomena. The interfacial ferromagnetism can be observed at the interface of paramagnetic LaNiO3 (LNO) and G-type antiferromagnetic SrMnO3 (SMO). Through the macroscopic magnetic and transport measurements and the microscopic x-ray magnetic circular dichroism signals, the obvious interfacial ferromagnetic behavior exhibited in the thicker superlattices. Using x-ray absorption spectroscopy and x-ray photoelectron spectroscopy measurements, the polar mismatch-induced charge redistribution in Ni and Mn ions accurately demonstrates the dependence on the varying thickness of LNO/SMO superlattices. These results suggest that the ferromagnetic double-exchange interaction of Mn3+–Mn4+ increases and the ferromagnetic super-exchange interaction of Ni2+–Mn4+ decreases with the increasing thickness of LNO/SMO superlattices. Consequently, the obvious ferromagnetic behavior in the thicker superlattices is induced by the double-exchange interaction. For the thinner LNO/SMO superlattice, the interfacial super-exchange ferromagnetic state is offset by the double-exchange ferromagnetism. This is the crucial reason behind the fact that ferromagnetism is hard to exist in the prior LNO/SMO superlattices. Our findings highlight the intrinsic mechanism responsible for the interfacial ferromagnetism and the significance of understanding polar mismatch at the interface of heterostructures.

The effect of composite configurations of Fe ionic spins on the dielectric properties in Sm-doped CeFeO3 ceramics

The Sm-doping effect on the crystal structure, dielectric and magnetic properties of CeFeO3 ceramics are systemically investigated. A giant dielectric response with high dielectric constant and low dielectric loss at room temperature (RT) is observed in Ce0.5Sm0.5FeO3 compounds. The increase of the dielectric constant is attributed to the increase of the ratio of Fe2+/Fe3+ ionic contents due to the charge transfer between Ce3+ and Fe3+ ions induced by Sm doping. Besides, the starting temperature T1 of spin-reorientation transition from Γ4 (Gx, Ay, Fz) to Γ1 (Ax, Gy, Cz) increases with Sm doping, and even reaches to a higher one than RT. Meanwhile, composite spin configurations of Fe3+ ions containing Γ1 and/or Γ2 (Fx, Cy, Gz) are found at RT in 0.2≤x ≤ 0.5 samples (x is Sm doping level), besides Γ4 state, whose formation originates from the strengthening of the anisotropic exchange interactions between Fe3+ and Ce3+/Sm3+ spins and the coexistence of Ce- and Sm-rich regions caused by Sm doping. It is suggested that the combining and competing functions of the Fe2+-Fe3+ ferromagnetic double-exchange interaction related to the Fe2+ ionic content and the composite spin configurations of Fe3+ ions containing Γ1 and/or Γ2 dominate the dielectric loss of Ce1-xSmxFeO3 ceramics. The results provide a different view for the physical theory and adjustment of the dielectric properties for applications.

First-principles study of magnetism and phase stabilities of V2 based antiferromagnetic Heusler alloys

We investigate the phase stability and magnetism of V2 based antiferromagnetic semiconductors by first-principles calculations. We first analyze the phase stability of the designed alloys by calculating the convex hull and find that keeping Al atoms in the Z sites is crucial to guarantee the stability against the segregation. The V2YAl (Y=V, Nb, and Ta) systems have relatively small hull distances and Néel temperatures higher than 1000 K are evaluated. The strong antiferromagnetic coupling between V atoms is rapidly decreasing with increasing the number of electrons due to the appearance of ferromagnetic double-exchange interaction. By applying a uniaxial strain to induce tetragonal distortion, a relatively large magneto-crystalline anisotropy energy is obtained for V2TaAl. It is claimed that V2YAl are thought to be good candidates for antiferromagnetic spintronics including gate-tunable magnetic properties.

Elastic strain control of electronic structure, and magnetic properties of [Pr1−xCaxMnO3/SrTiO3]15 superlattices

We report the growth, electronic structure, and in-plane magnetic properties of pulsed laser deposition grown 2D superlattice structures [Pr0.7Ca0.3MnO3/SrTiO3]15 and [Pr0.5Ca0.5MnO3/SrTiO3]15 on (001) oriented SrTiO3 and LaAlO3 single crystal substrates. The x-ray reflectivity measurements reveal well-defined interfaces between the manganite and titanate layers along with the existence of Kiessig fringes, providing the evidence for the smooth periodic superlattice structure. The reciprocal space mapping provides signature of tetragonal distortion in all the superlattices. The electronic structure determined from the x-ray photoelectron spectroscopy reveals divalent Sr and Ca, tetravalent Ti, and mixed valent Mn with a pronounce shift of binding energy peaks toward the higher energy side in the superlattices grown on (001) oriented LaAlO3 as compared to those grown on SrTiO3. These superlattices exhibit highly anisotropic ferromagnetic character. We used the law of approach to saturation to determine the anisotropy field (HK) and cubic anisotropy constant (K1) for all the investigated superlattices. This analysis yields the highest HK∼9 kOe and K1∼8×105 erg/cc for the [Pr0.7Ca0.3MnO3/SrTiO3]15 superlattice system. Furthermore, significant enhancement of the overall magnetic moment and a decrease in TC (&amp;lt;100 K) was observed in the case of LaAlO3 grown superlattice, which indicates a substantial role of residual elastic strain on the magnetic ordering. Our results indicate that the strain induced elongation of MnO6 octahedra leads to finite possibility of non-orthogonal overlapping of orbitals in the presence of large crystal field splitting of eg levels, which, in turn, causes suppression of the ferromagnetic double exchange interaction.

Effect of yttrium doping on the structure, dielectric multiferroic and magnetodielectric properties of Bi5Ti3FeO15 ceramics

Multiferroic Bi5−xYxTi3FeO15 (BYTF-x, x = 0, 0.1, 0.3, 0.5, 0.7) ceramics were synthesized through the conventional solid-state reaction. The structure, dielectric, multiferroic and magnetodielectric properties of BYTF-x were investigated in detail. X-ray diffraction confirmed that all the samples were layered Aurivillius structure. Upon increasing Y content, the grain size of samples slightly decreases. The dielectric permittivity increased with Y doped. The Y doping has no effect on microstructural changes of plate-like grains which verified though field-emission scanning electron microscopy. The minimum remanent polarization (2Pr = 2.48 μc/cm2) was observed in BYTF-0.3 ceramic and the maximum magnetodielectric coefficient value of 1.23% was obtained in BYTF-0.3 ceramic perhaps result from the coexistence of Fe2+ and Fe3+. Additionally, weak ferromagnetic is only found in BYTF-0.3 ceramic. The ferromagnetism can be attributed to ferromagnetic double exchange interactions (Fe2+–O–Fe3+) and the spin canting of tilting FeO6 octahedra via the Dzyaloshinskii–Moriya interaction. These results indicate that Y doping Aurivillius phase may be the potential candidates for exploring superior room-temperature multiferroics.

Large vertical hysteretic shift and signature of exchange bias in BiFeO3/SrRuO3 heterostructure

Abstract We present the results of magnetic study on G-type antiferromagnetic BiFeO 3 /ferromagnetic SrRuO 3 heterostructure grown on (001) SrTiO 3 substrate using pulsed laser deposition technique. We observe a large positive vertical magnetization shift (M Shift ~35%) in the magnetic hysteresis (M − H) loop in the direction of the cooling fields (±30 kOe). The M Shift is essentially due to the presence of the interfacial pinned Ru 4+ moments and the local defects/vacancies present in the SRO layer. The pinned Ru 4+ moments strongly attached to Fe 3+ moments of BiFeO 3 layer through exchange interaction may result in the exchange bias (EB) effect. The positive M Shift and negative EB effect suggest the ferromagnetic double exchange interaction Fe 3+ -O-Ru 4+ , across the interface.

Study on the structural and magnetic properties of Fe/Co co-doped Bi4Ti3O12 ceramics

Polycrystalline Bi4(Ti3-xFex/2Cox/2)O12 (0 ≤ x ≤ 0.4) ceramics are prepared by solid state reaction method. The low temperature ferromagnetism is successfully induced by Fe/Co co-doping. Particularly, the x = 0.3 ceramics possess the largest remnant magnetization (2Mr) of about 0.272 emu/g at 100 K. Furthermore, all the doped ceramics undergo a ferromagnetic to paramagnetic transition, and show typical spin glass behavior, which is confirmed by the isothermal remnant magnetization and Memory Effect. The magnetic mechanisms probably originate from the coexistence and competition between ferromagnetic double exchange interactions and antiferromagnetic superexchange interactions, which lead to the appearance of the spin glass behavior in the doped ceramics and the strongest ferromagnetism in the x = 0.3 ceramics. The present work provides basic data and theoretical reference for the exploitation of the new multifunctional materials.

Effect of Ca doping on structural, magnetic and electronic properties of TbMnO3

First principles calculations have been carried out to investigate the structural, magnetic and electronic properties of the multiferroic manganite TbMnO3 with and without Ca doping. For pure TbMnO3, results show that spiral-spin antiferromagnetic ordering is energetically found favorable. The presence of Ca doping at the manganite Tb1−xCaxMnO3 with x = 0.25, 0.5 and 0.75 directly affects the Mn ordering. For x ≤ 0.5, the ferromagnetic ordering is most favored. While for x = 0.75, the most stable magnetic configuration is antiferromagnetic arrangement. It is found that the decrease in the intensity of the ferromagnetic double-exchange interaction has been correlated with the increase in the Ca content and the Mn-O-Mn bond angle.

Magnetic Properties and Mössbauer Investigations of La0.67Sr0.33FexMn1−xO3 (x = 0 and 0.5) Perovskites

We report magnetic phase separation in pure La0.67Sr0.33FexMn1−xO3 (x = 0 and 0.5) ceramic samples. Rhombohedral crystal structures obtained with R3C space group show no significant changes in the lattice structures due to the close values of ionic radii of Fe3+ and Mn3+ ions. However, significant changes occur in the magnetic properties due to competing ferromagnetic (FM) and antiferromagnetic (AFM) interactions because of the presence of Fe3+ substitution. The FM double exchange interactions (DE) (Mn3+–O–Mn4+) appears suppressed by AFM superexchange interactions (Fe3+–O–Mn4+, Fe3+–O–Fe3+, Mn4+–O–Mn4+). The saturation magnetization for x = 0 has the highest value of approximately 80 emu/g at 2 K, which dropped significantly to approximately 5 emu/g at 2 K for the x = 0.5 sample. The coercivity (Hc) for x = 0.5 increased from 161 Oe at 300 K to 786 Oe at 2 K compared with that of x = 0 which varied from 110 to 150 Oe. A value of Hc(0) = 1.5 ± 0.04 kOe was extrapolated from the model fit to the temperature dependence of Hc. The temperature-dependent 57Fe Mossbauer spectroscopy measurements show the presence of Fe in two different environments that have an AFM Fe3+–O–Mn4+ and Fe3+/2+–O–Fe3+/2+ coordination. The unequal fraction population of Fe ions at both AFM environments seems to increase the exchange bias effect.