Structural Phase Diagram of Ca1−xYxMnO3: Characterization of Phases

Vega, Daníel; Polla, G.; Leyva, A.G.; König, P.; Lanza, H.; Esteban, A.; Aliaga, H.; Causa, M.T.; Tovar, Michael; Alascio, B.

doi:10.1006/jssc.2000.9023

Cited by 36 publications

(17 citation statements)

References 17 publications

(16 reference statements)

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“…The typical lattice parameters are found to be a ¼ b ¼ 6.132 Å and c ¼ 11.368 Å for YMnO 3 . These values are comparable to those reported by Vega et al [25] in YMnO 3 . All the lattice parameters and unit cell volumes are given in Table 1.…”

Section: Resultssupporting

confidence: 94%

Magnetic properties of electron-doped Y1−xCexMnO3 compounds

Srivastava

Kar

Ravi

et al. 2008

Journal of Magnetism and Magnetic Materials

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Section: Resultssupporting

confidence: 94%

Magnetic properties of electron-doped Y1−xCexMnO3 compounds

Srivastava

Kar

Ravi

et al. 2008

Journal of Magnetism and Magnetic Materials

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“…Ceramic polycrystalline samples of Ca 1-x Y x MnO 3 were prepared by solid state reaction methods [8]. For 0 ≤ x ≤ 0.25 we obtained single phase samples and room temperature x-rays diffractograms were indexed in the orthorhombic Pnma structure.…”

Section: Resultsmentioning

confidence: 99%

High temperature susceptibility in electron doped Ca_1 xY_xMnO₃: double exchange versus superexchange

Aliaga

Causa

Tovar

et al. 2002

J. Phys.: Condens. Matter

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Abstract. We present a study of the magnetic properties of the electron doped manganites Ca 1-x Y x MnO 3 (for 0 ≤ x ≤ 0.25) in the paramagnetic regime. For the less doped samples (x ≤ 0.1) the magnetic susceptibility, χ(T), follows a Curie-Weiss (CW) law only for T > 450 K and, below this temperature, χ -1 (T) shows a ferrimagnetic-like curvature. We approached the discussion of these results in terms of a simple mean-field model where double exchange, approximated by a ferromagnetic Heisenberg-like interaction between Mn 3+ and Mn 4+ ions, competes with classical superexchange. For higher levels of doping (x ≥ 0.15), the CW behaviour is observed down to the magnetic ordering temperature (T mo ) and a better description of χ(T) was obtained by assuming full delocalization of the e g electrons. In order to explore the degree of delocalization as a function of T and x, we analyzed the problem through Montecarlo simulations. Within this picture we found that at high T the electrons doped are completely delocalized but, when T mo is approached, they form magnetic polarons of large spin that cause the observed curvature in χ -1 (T) for x ≤ 0. IntroductionManganites, responding to the formula B 1-x A x MnO 3 (with B = divalent alkaline earth and A = trivalent rare earth), have prompted a burst of research activity in the last decade, as they enclosed not only very rich physics but also interest in technological applications. The dynamics of these systems is mainly governed by the Mn ions, whose average valence changes with x between 4+ and 3+. The Mn 4+ ions have noncompensated spins in t 2g 3 configuration that give rise to localized S = 3/2 spins. On the other hand, the Mn 3+ ions have an extra e g electron (with s = ½), that couples ferromagnetically (FM) to the t 2g spins. The e g electrons tend to be itinerant and lower their kinetic energy by polarizing with FM character the localized t 2g spins. This process is known [1] as double exchange (DE) and in these materials competes with the classical superexchange (SE) interaction between Mn ions.In Ca 1-x La x MnO 3 were the whole series, from x = 0 to x = 1, can be obtained with the perovskite structure, the behaviour in the electron and hole doping regions were found different. The parent compounds are indeed quite different: while LaMnO 3 , a Jahn-Teller system, displays A-type [2] antiferromagnetism, where ferromagnetic (FM) planes order antiferromagnetically (AFM), the non Jahn-Teller CaMnO 3 is a G-type antiferromagnet, where each magnetic moment orders AFM with his nearest neighbours [2]. Most studies have been performed on hole doped compounds where ferromagnetism and colossal magnetoresistance (CMR) were found. In the range of electron doping, transport and magnetization studies on Ca 1-x La x MnO 3 showed that a complete FM state is never reached and different models were discussed in order to explain the magnetic properties at low temperatures [3,4]. These studies showed that in this region of doping new and very interesting phenomena appear as a conseq...

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“…1) we found two regimes: for T > 500 K, a pseudo-tetragonal O-phase and for lower temperatures, a more distorted [3] O 0 -phase (with b=O2oc). The cell volume (V ) decreases linearly with T but at E250 K, where a small discontinuity in bðTÞ is observed, V stops to decrease and remains constant below this temperature.…”

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confidence: 93%

“…It would be interesting to know how this behaviour reflects on other physical properties. With this aim we present an experimental study on electric transport, electron spin resonance (ESR) and crystalline structure performed on the half-doped and low /r A S manganite Y 0.5 Ca 0.5 MnO 3 .Samples of Y 0.5 Ca 0.5 MnO 3 were prepared by solid state reaction [3], and studied by X-ray diffraction. We observed that the material is single phase in all the studied T range (20/750 K).…”

mentioning

confidence: 99%