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The present work reports the in-field 57Fe M ö ssbauer spectroscopy measurements on polycrystalline R3Fe5O12 (RIG, R=Y, Gd, Ho, Tm, & Yb) rare-earth iron garnets. The contrast between the effective hyperfine field (Heff) values of two Fe3+ sites (tetrahedral, d- and octahedral, a- sites) across magnetic compensation (TComp) facilitates to probe the Fe3+ sublattice spin reversal in RIG systems (R=Gd, Ho and Yb) exhibiting magnetic compensation. Further, the analysis of relative intensity of absorption lines in a sextet from the field dependent 57Fe M ö ssbauer spectroscopy measurements carried out in polycrystalline YbIG, below TComp, show the clear signatures of field induced perpendicular Fe3+ spin configuration when applied external field is 50 kOe. [ABSTRACT FROM AUTHOR]

Highlights • Surface antiferromagnetism of the Cr(0 0 1) c(2 × 2) surface. • Quantitative determination of the antiferromagnetic coupling angles. • New spin quantization axes along the [1 1 0] of Cr(0 0 1). Abstract We present spin-polarized scanning tunneling microscopy results for 8 micrometer thick, chromium (0 0 1)-oriented thin films deposited using molecular beam epitaxy on MgO(0 0 1) substrates, achieving a smooth, atomically-stepped staircase morphology. The c(2 × 2) surface structure of the Cr(0 0 1) surface was found via atomically-resolved scanning tunneling microscopy images and dI/dV spectroscopy. A practical method of interpreting spin-polarized scanning tunneling microscopy dI/dV images was developed and applied to the c(2 × 2) Cr(0 0 1) surface structure. A 180° spin reversal between atomic layers, characteristic of a topological, layer-wise antiferromagnetic spin structure, was quantitatively verified. In addition, the spin anisotropy directions for 3 different antiferromagnetic, atomic staircase domains occurring on the c(2 × 2) surface were quantitatively determined to coincide with the [1 0 0], [0 1 0], and [1 1 0] crystallographic axes of chromium. [ABSTRACT FROM AUTHOR]

Magnetic properties of the Er(Co,Mn)O3 solid solution result from a subtle interplay of different interactions between erbium moments and several other magnetic entities present in this system: Mn3+, Mn4+, Co2+, Co3+, as well as double-exchange interactions among them. The special case of the 0.5:0.5 = Co:Mn substitution is particularly important since ferromagnetic domains may reorientate both under low and high external magnetic fields. Magnetic dilution of the erbium sublattice by non-magnetic yttrium (same valence and size) allows separating out the antiferromagnetic 4f-3d interactions leaving just the ferromagnetic Co2+-Mn4+ transition metal sublattice. Magnetic properties of the ErxY1-xCo0.50Mn0.50O3 (0.0 ≤ x ≤ 1.0) solid solution are presented, going from ferromagnetism (x = 0; YCo0.5Mn0.5O3) to ferrimagnetism (x = 1; ErCo0.5Mn0.5O3). Antiferromagnetic interactions get stronger while the Co/Mn ferromagnetic domains become harder to rotate when the rare-earth sublattice is progressively filled with erbium ions of large magnetic moments. A linear dependence with x(Er) is observed for the critical field Hcrit related to the reorientation of domains, going from 1.3 T up to 3.5 T, for x = 0 and 1, respectively. At the same time, the compensation temperature Tcomp increases and the spontaneous magnetization Mrem decreases with increasing content of erbium.Las propiedades magnéticas de las soluciones sólidas ErxY1-xCo0.50Mn0.50O3 (0.0 ≤ x ≤ 1.0) son consecuencia de una sutil interrelación de las diferentes interacciones entre los momentos magnéticos del Er3+ y de otras entidades magnéticas presentes en el sistema: Mn3+, Mn4+, Co2+, Co3+, así como las interacciones de doble canje entre ellas. El caso especial de la sustitución 0.5:0.5 = Co:Mn es particularmente importante puesto que los dominios ferromagnéticos pueden reorientarse bien con campos externos bajos como con altos. La dilución magnética de la subred de Er3+ por el ión no-magnético Y3+ (del mismo tamaño y valencia) permite separar las interacciones antiferromagnéticas 4f-3d dejando solamente las interacciones ferromagnéticas Co2+-Mn4+ de la subred de los metales de transición. Las propiedades magnéticas de las soluciones sólidas ErxY1-xCo0.50Mn0.50O3 (0.0 ≤ x ≤ 1.0) se presentan como variando desde ferromagnetismo (x = 0; YCo0.5Mn0.5O3) a ferrimagnetismo (x = 1; ErCo0.5Mn0.5O3). Las interacciones antiferromagnéticas se hacen más fuertes mientras que los dominios ferromagnéticos se hacen más difíciles de rotar cuando la subred de la tierra rara se va llenando progresivamente con iones Er3+, de momento magnético alto. Se observa una dependencia lineal con x(Er) del campo crítico Hcrit relacionado con la reorientación de dominios, variando desde 1.3 T hasta 3.5 T, para x = 0 y 1, respectivamente. Al mismo tiempo, la temperatura de compensación, Tcomp aumenta y la magnetización espontánea, Mrem disminuye con el contenido creciente de Er3+.

Partial substitution of Mn by a divalent metal in rare-earth manganites REMexMn1 xO3 results in the simultaneous presence of Mn3+ and Mn4+. The RE sublattice has its own properties and can interact with the local field imposed by the ferromagnetic Mn network. Its orientation differs depending on the RE nature, adopting a parallel direction with respect to the local field, or it may align in opposite direction, resulting in uncompensated antiferromagnetic structure. For divalent elements (e.g., Ni2+), the solid solution is limited to RENi2+0.5Mn4+0.5O3 ; at this frontier composition, the ferromagnetic superexchange Ni2+-O-Mn4+ interactions are optimized. For Me = Co, this limit can be extended, meaning that part of cobalt takes a 3+ state ; in this case, presence of Co3+ modifies the magnetic coupling, leading to qualitatively different behaviours during the ZFC/FC cycles. In this work, we have chosen the specific composition REMe0.50Mn0.50O3 for which the strongest magnetic interactions are expected, emphasizing the results obtained for Me = Ni and Co and comparing various rare-earth elements (RE = Y, La, Pr, Nd, Eu, Gd and Er). As expected from the general behaviour of the series (RE,Ca)MnO3, we find that in the RE(Mn,Me)O3, the larger the RE ionic radius, the highest the transition temperature, reaching 235 K in LaCo0.50Mn0.50O3 compared to 68 K in ErCo0.50Mn0.50O3.La sustitución parcial de Mn por un catión divalente en manganitas de tierras raras TRMexMn1 xO3 induce la presencia simultánea de Mn3+ y Mn4+. La subred TR tiene sus propiedades intrínsecas y puede interactuar con el campo local impuesto por la red ferromagnética del Mn. Su orientación difiere dependiendo de la naturaleza de la TR, adoptando una dirección paralela con respecto al campo local, o puede alinearse en sentido opuesto, produciendo una estructura antiferromagnética no compensada. Para cationes divalentes (Ni2+), la solución sólida está limitada a TRNi2+0.5Mn4+0.5O3; en este límite, las interacciones de supercanje Ni2+-O-Mn4+ se optimizan. Para Me = Co el límite se amplía a causa de que el cobalto puede tomar el estado 3+; en este caso, la presencia de Co3+ modifica el acoplamiento magnético llevando a comportamientos cualitativamente diferentes durante los ciclos ZFC/FC. En el presente trabajo se ha escogido la composición específica TRMe0.50Mn0.50O3 para la cual se esperan las interacciones magnéticas más intensas, remarcando los resultados obtenidos para Me = Ni y Co y comparando varios elementos de tierras raras (TR = Y, La, Pr, Nd, Eu, Gd y Er). Como se esperaba de acuerdo con el comportamiento general de las soluciones sólidas (TR,Ca)MnO3, se ha hallado que en las series TR(Mn,Me)O3, cuanto mayor es el radio iónico de la TR mayor es la temperatura de transición, alcanzando 235 K para composiciones LaCo0.50Mn0.50O3 frente a 68 K para ErCo0.50Mn0.50O3.

Partial substitution of the rare-earth by calcium at the cationic site of the ABO3 perovskites may show extraordinary effects of spin reversal due to a negative polarization between the rare-earth and the manganese networks, as it occurs in the solid solution Gd1‑xCaxMnO3. We present herein similar effects in gadolinium perovskites of the Gd(Me,Mn)O3 type, in which the manganese sublattice has been partially substituted by transition metal elements Me, leaving the gadolinium network intact. The spin reversal phenomena is observed at a critical concentration of x(Me) = 1/3, which implies an optimum number of pairs Mn3+-Mn4+. Néel temperatures of 48 and 67 K are obtained for Me = Co and Ni, respectively, at the optimum concentration of substituent. A comparison between these different solid solutions allows us to generalize the interpretation of two interacting magnetic sublattices : a Mn-based ferromagnetic one and a negatively-aligned gadolinium network.La sustitución parcial del lantánido por el elemento calcio en el sitio catiónico (sitio A) de la perovskita ABO3 puede dar lugar a efectos importantes ligados a una inversión del espín. Dicha inversión se debe a una interacción negativa entre la tierra rara y la subred de manganeso, tal como ocurre en la solución solida Gd1-xCaxMnO3. Se presentan en este trabajo efectos similares que ocurren en las perovskitas de gadolinio de fórmula Gd(Me,Mn)O3, en las cuales la subred de manganeso (sitio B) ha sido reemplazada parcialmente por otros metales de transición Me, dejando intacta la subred de gadolinio. Se observa el fenómeno de inversión de espín para una concentración crítica x(Me) = 1/3, para la cual se logra una cantidad óptima de pares Mn3+‑Mn4+. Para esta concentración crítica se observan temperaturas de Néel antiferromagnéticas del orden de 48 y 67 K, respectivamente para Me = Co y Ni. Un análisis comparativo entre estos diferentes sistemas permite generalizar la interpretación de la existencia de dos subredes magnéticas que interactúan : una subred ferromagnética relacionada con el Mn, y una subred de gadolinio cuyos espines se orientan en sentido contrario a la primera.

The control of the spin orientation transitions in perovskites containing manganese, cobalt, iron, and chromium, based on crystal chemistry factors is reviewed. We describe herein the effect of the size and of the magnetic nature of the Ln3+ cations and of the doping and large substitutions at the octahedral sites. Spin blockade introduced by nanostructural effects and magnetic anisotropy induced by laser pulse application are also discussed. [ABSTRACT FROM AUTHOR]

Abstract: Magnetic hysteresis displacement, thermal inversion of the magnetization, hysteresis loops jumps and crossing branches of hysteresis loops at low magnetic fields are reviewed. Most of these phenomena have been observed in magnetic oxide systems, particularly in perovskite-type manganites and chromites. The paper takes into account structural considerations and different geometrical parameters, such as volume or thin layers. [Copyright &y& Elsevier]

Abstract: Substitution of Mn by a divalent metal in rare-earth manganites REMe x Mn1− x O3 results in the simultaneous presence of Mn3+ and Mn4+. The RE sublattice interacts with the local field imposed by the Mn network and may orientate in a parallel direction, or align in the opposite direction resulting in an uncompensated antiferromagnetic structure. We present the magnetic properties of ErCo x Mn1− x O3, in which manganese is substituted by cobalt. Coexistence of different interactions leads to unusual phenomena: a spin reversal, a step-like transition due to a reorientation of domains, a relaxation mechanism connected to the rotation energy of domains, the intersection of increasing and decreasing branches in the magnetization loops. [Copyright &y& Elsevier]

Abstract: The (Mn1−x Cd x )Cr2S4 phases (0≤ x ≤0.6) have been synthesized from the corresponding elements at 1123K. These samples were characterized by powder X-ray diffraction (XRD) and magnetic susceptibility. The (Mn1−x Cd x )Cr2S4 compounds crystallize in the space group Fd-3m with cell parameters a =10.101(6)Å, 10.139(3)Å, 10.165(2)Å, and 10.192(1)Å for x =0, 0.2, 0.4 and 0.6, respectively. An overall ferrimagnetic behavior is observed for all samples. The ferromagnetic component increases rapidly when manganese is substituted by non-magnetic cadmium, as shown by ZFC/FC measurements. At the same time, the value of the magnetization M 50 at 50kOe, deduced from M(H) loops, also increases with increasing cadmium content because the antiferromagnetic alignment between chromium and manganese spins is progressively lost, leading toward well aligned moments pointing into the same direction. These results are explained by a rearrangement of the chromium spins when Mn located at the tetrahedral sites, is substituted by Cd. [Copyright &y& Elsevier]

Abstract: We present herein a comparison of the magnetic properties of bulk ceramics and thin films of the ferrimagnetic ErCo0.50Mn0.50O3 compound. Epitaxial thin films were deposited onto (100) SrTiO3 substrates by pulsed-laser ablation while bulk ceramics were prepared by solid state reaction. When cooling under low applied fields, a spin reversal is observed in both thin film and bulk due to the competition between two magnetic sublattices (Co/Mn and Er) coupled by a negative exchange interaction. Original features are observed in the M(H) loops for bulk materials: abrupt jumps at 4T due to a reorientation of domains, while in the low field region, the increasing and decreasing branches of the magnetization intersect each other. In the thin film, the ordering temperature increased from 69 to 75K, and the ZFC anomaly (AF transition) became sharper, compared to the bulk specimen. The oxygen content and the microstructure are crucial to observe the intersection of the magnetization branches. [Copyright &y& Elsevier]

Abstract: The erbium-based manganite ErMnO3 has been partially substituted at the manganese site by Co in the general formula ErCo x Mn1−x O3. The perovskite orthorhombic structure is found from x(Co)=0.3 up to x(Co)=0.7, provided that the synthesis is performed under oxygenation conditions to favour the presence of Co3+. Magnetic properties show unusual phenomena, correlated with the presence of different magnetic entities (i.e., Er3+, Co2+, Co3+, Mn3+, Mn4+): the overall magnetic moment reverses its sign when the sample is cooled under an external magnetic field, while the magnetization loops performed at T <4K show intersecting branches at low fields and a sudden jump at high fields. A phenomenological model of two interacting sublattices, coupled by an antiferromagnetic exchange interaction, explains the inversion of the overall spin, while the high-field discontinuity is explained in terms of dynamical models. [Copyright &y& Elsevier]

Abstract: Rare-earth-based manganites ABO3 may present interesting properties when the lanthanide (A-site) and/or the manganese (B-site) are partially substituted by divalent elements. Heavy lanthanides are particularly appealing because of the expected interplay between the intrinsic magnetic properties of the rare-earth element (Ln) and those of the ferromagnetic manganese sublattice. As such, a spin reorientation has been observed during magnetization-versus-temperature cycles due to a negative exchange interaction between Mn and Ln. We present herein high-quality epitaxial thin films (∼200nm thick) of Gd0.67Ca0.33MnO3 deposited onto (100) SrTiO3 substrates by pulsed-laser deposition. Enhanced properties were observed in comparison with bulk samples. The magnetic transition temperature T c of the as-grown films is much higher than the corresponding bulk values. Most interesting, magnetization measurements performed under small applied fields, exhibit magnetization reversals below T c, no matter whether the film is field-cooled (FC) or zero-field-cooled (ZFC). The reversal mechanism is discussed in terms of a negative exchange f–d interaction and magnetic anisotropy, this latter enhanced by strain effects induced by the lattice mismatch between the film and the substrate. [Copyright &y& Elsevier]

Abstract: The erbium-based manganite ErMnO3 has been partially substituted at the manganese site by the transition-metal elements Ni and Co. The perovskite orthorhombic structure is found from x(Ni)=0.2–0.5 in the nickel-based solid solution ErNi x Mn1− x O3, while it can be extended up to x(Co)=0.7 in the case of cobalt, provided that the synthesis is performed under oxygenation conditions to favor the presence of Co3+. Presence of different magnetic entities (i.e., Er3+, Ni2+, Co2+, Co3+, Mn3+, and Mn4+) leads to quite unusual magnetic properties, characterized by the coexistence of antiferromagnetic and ferromagnetic interactions. In ErNi x Mn1− x O3, a critical concentration x crit(Ni)=1/3 separates two regimes: spin-canted AF interactions predominate at xx crit. Spin reversal phenomena are present both in the nickel- and cobalt-based compounds. A phenomenological model based on two interacting sublattices, coupled by an antiferromagnetic exchange interaction, explains the inversion of the overall magnetic moment at low temperatures. In this model, the ferromagnetic transition-metal lattice, which orders at T c, creates a strong local field at the erbium site, polarizing the Er moments in a direction opposite to the applied field. At low temperatures, when the contribution of the paramagnetic erbium sublattice, which varies as T −1, gets larger than the ferromagnetic contribution, the total magnetic moment changes its sign, leading to an overall ferrimagnetic state. The half-substituted compound ErCo0.50Mn0.50O3 was studied in detail, since the magnetization loops present two well-identified anomalies: an intersection of the magnetization branches at low fields, and magnetization jumps at high fields. The influence of the oxidizing conditions was studied in other compositions close to the 50/50=Mn/Co substitution rate. These anomalies are clearly connected to the spin inversion phenomena and to the simultaneous presence of Co2+ and Co3+ magnetic moments. Dynamical aspects should be considered to well identify the high-field anomaly, since it depends on the magnetic field sweep rate. [Copyright &y& Elsevier]

Abstract: The gadolinium-based manganite GdMnO3 of perovskite structure has been partially substituted at the manganese site by transition metal elements Me like Cu, Ni and Co, leading to a general formula GdMe x Mn1− x O3, in which different magnetic entities (e.g., Gd3+, Cu2+, Ni2+, Co2+, Co3+, Mn3+, Mn4+) can coexist, depending on charge equilibrium conditions. For divalent cations such as Cu2+ and Ni2+, the solid solution extends from x(Me)=0–0.5, with O-type orthorhombic symmetry . When the substituting element is cobalt, the solid solution extends over the whole range [0⩽x⩽1], changing from O′-type symmetry to O-type for x>0.5. In this latter case, the synthesis is performed under oxygen flow, which allows the cobalt ion to take a 3+ oxidation state. Magnetic properties were studied through susceptibility and magnetization measurements. A paramagnetic–ferromagnetic transition occurs at T c, due to double-exchange interactions between transition metal ions (Mn3+–Mn4+, Ni2+–Mn4+, Co2+–Mn4+), leading to an optimum value at x(Me)=0.50 (T c=145 and 120K, for GdNi0.5Mn0.5O3 and GdCo0.5Mn0.5O3, respectively). Different situations were identified, among them, a spin reversal in GdNi0.3Mn0.7O3, strong ferromagnetic interactions in GdNi0.5Mn0.5O3, large coercive fields in GdCo0.5Mn0.5O3 or Co3+–Mn4+ antiferromagnetic interactions in GdCo0.9Mn0.1O3. Most of these situations are explained by a phenomenological model of two magnetic sublattices: a transition-metal |Me+Mn| network which orders ferromagnetically at T c and a gadolinium sublattice, composed of independent Gd3+ ions. These networks are antiferromagnetically coupled through a negative exchange interaction. The local field created by the ferromagnetic |Me+Mn| lattice at the gadolinium site polarizes the Gd moment in a direction opposite to the applied field. When the magnetization of paramagnetic gadolinium, which varies as T −1, gets larger than the ferromagnetic magnetization of the transition metal, which is “frozen” at T

Solid solutions of Dy1−xCaxMnO3 (0.00&les;x&les;0.60) were prepared by solid state reaction of oxides and carbonates. Sintered bodies were obtained by firing between 1250 and 1450 °C. All compositions, including DyMnO3, crystallize in a perovskite structure of O′-type orthorhombic symmetry and space group Pbnm. Increase of Ca2+ content leads to a monotonic decrease of the orthorhombicity factor b/a. Electrical measurements show a semiconducting behavior for all compositions. The room temperature conductivity increases with Ca content, attaining relatively high values at x=0.60 and a correlative very low value of the activation energy. Thermally-activated small-polaron hopping mechanism controls the conductivity. Antiferromagnetic interactions between Dy spins are observed at TN=9.5 K. DyMnO3 behaves as a metamagnetic-like system, with no remanent magnetization at zero field. ZFC/FC cycles and the thermal evolution of the remanent magnetization of the Dy1−xCaxMnO3 solid solution show the presence of two interacting magnetic networks: a Dy sublattice, with a Curie–Weiss thermal dependence above TN, aligned antiparallel to the ferromagnetically ordered (Tc=80 K) Mn network. The local field at a given site depends on the exchange interaction J between these two sublattices, leading to a spin reversal when the magnetic moment of the dysprosium network is larger than the one produced by the ferromagnetic Mn sublattice. [Copyright &y& Elsevier]

We investigate the spin reversal of two coupled magnetic impurities in the transport processes of electrons in a one-dimensional chain. The impurities are side coupled to the chain and the electrons are injected and tunneling through it. The transmission coefficient of electrons and the polarization of impurities are calculated by the use of the equivalent single-particle network method for the correlated system. It is found that both the transmission coefficient and the polarization of impurities depend on the initial state of impurities and the impurity spins can be converted into the direction of electron spin if the injected electrons are polarized and the number of electrons is large enough. The evolution of the spin-reversal processes is studied in details. [Copyright &y& Elsevier]

We have investigated the structural and magnetic phase transitions in Sr doped polycrystalline Tb 0.55 Sr 0.45 MnO 3 , using temperature-dependent high-resolution neutron powder diffraction in the HRPT diffractometer at PSI to address the origin of magnetization reversal at low temperature. The solid solution Tb 0.55 Sr 0.45 MnO 3 crystallizes in O′ type orthorhombic structure having the Pnma symmetry. The substitution of the divalent cation of Sr2+ at the site of Tb3+ dilutes the Mn–Tb interaction and affects the magnetic structure, which was observed by the field and temperature-dependent dc magnetization and neutron diffraction study. The temperature-dependent zero field-cooled and field cooled dc magnetization study reveals the indication of spin reversal phenomena, which is the nature of canted antiferromagnetic or ferrimagnetic transition at 100 Oe because of Mn–Mn sub-lattices interaction below 65 K. By increasing the applied magnetic field up to 20 kOe, a weak ferromagnetic type of behaviour is observed. The field-dependent magnetization shows weak coercivity due to the canted spin structure at low temperatures. The low-temperature neutron diffraction study of polycrystalline Tb 0.55 Sr 0.45 MnO 3 reveals the non-collinear canted antiferromagnetic structure due to Tb ordering at 1.5 K, which turns into a non-collinear ferromagnetic structure along with spin canting followed by the spin reversal phenomena at 25 K. • Structural analysis reveals the O′ type of orthorhombic lattice distortion in polycrystalline Tb 0.55 Sr 0.45 MnO 3. • Cation doping of Sr2+ doping induces a mixed-valent state of Mn3+/Mn4+ and dilutes the magnetic interactions of Tb3+ ion. • Neutron diffraction study of polycrystalline Tb 0.55 Sr 0.45 MnO 3 is observed using a temperature-dependent HRPT diffractometer @ PSI. • dc magnetization and magnetic structure study reveal the indication of spin reversal phenomena due to Mn–Mn sub-lattice interaction. • The spin reversal transition from non-collinear canted AFM structure to non-collinear canted FM phase transition is observed by NPD. [ABSTRACT FROM AUTHOR]

Aluminum doping produced the parasitic magnetization (Mpara) with high coercivity in 20 nm thin antiferromagnetic Cr2O3 films. By using the large coercive force of Mpara, whose direction is the same as the antiferromagnetic Cr2O3 surface spin, antiferromagnetic spin reversal can be detected through the vertical shift of the hysteresis loop of an antiferromagnetic‐Cr2O3/ferromagnet perpendicular exchange bias (PEB) coupling system. By analyzing both antiferromagnetic and ferromagnetic spin reversals in response to external magnetic field and temperature, each spin reversal mechanism in a PEB system is clarified. It is found that the competition among Zeeman energy due to Mpara, exchange coupling energy, and antiferromagnetic anisotropy energy decides the antiferromagnetic spin direction and, accordingly, PEB sign under different cooling fields, different temperatures, and different swept magnetic fields for PEB systems. This work might contribute to a deep understanding of spin reversal mechanism in a perpendicular exchange bias system. [ABSTRACT FROM AUTHOR]

Magnetic properties of (RE, Ca)MnO3 perovskites (RE=Gd, Dy) have been studied in the ordered state. The remanent magnetization Mrem reverses its magnetic moment, as if the external field was applied opposite to the initial direction. Results are interpreted in terms of two interacting networks, with negative exchange interaction between the RE and the ferromagnetic Mn lattices. [Copyright &y& Elsevier]

Abstract: Partial substitution of manganese by cobalt in rare-earth perovskites REMnO3 leads to unusual magnetic phenomena because of the simultaneous presence of Mn3+, Mn4+, Co2+ and Co3+ species. The magnetic nature of the RE cation plays a fundamental role in the magnetic properties. We present herein two specific families: for RE=La the magnetic behavior of the |Co+Mn| network is observed, while for Gd its strong magnetic moment interacts with the transition metals, leading to a spin reversal state. Magnetic interactions are maximized at x=0.50, as if two regimes exist: for x<0.5 Co substitutes Mn in the REMnO3 manganite, and for x>0.5 Mn substitutes Co in the RECoO3 cobaltite. [Copyright &y& Elsevier]