Electronic structure study of wide band gap magnetic semiconductor (La0.6Pr0.4)0.65Ca0.35MnO3 nanocrystals in paramagnetic and ferromagnetic phases

Dwivedi, G. D.; Joshi, Amish G.; Kumar, Sanjay; Chou, Hsiung; Yang, K. S.; Jhong, Dai-Jhen; Chan, Wen L.; Ghosh, Anup K.; Chatterjee, Sandip

doi:10.1063/1.4947466

Cited by 10 publications

(14 citation statements)

References 44 publications

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“…The binding energy value of Pr3d 5/2 is 933.1 eV which is typical for Pr 3+ state (Fig. 1(b)) [58], the shape and position of Pr3d spectra did not change depending on the sample treatments. For the initial sample Ca is in two states with BE values of 346.5 and 347.5 eV (Fig.…”

Section: X-ray Photoelectron Spectroscopymentioning

confidence: 78%

Oxygen transport in Pr nickelates: Elucidation of atomic-scale features

et al. 2020

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Pr 2 NiO 4+δ oxide with a layered Ruddlesden-Popper structure is a promising material for SOFC cathodes and oxygen separation membranes due to a high oxygen mobility provided by the cooperative mechanism of oxygen migration involving both interstitial oxygen species and apical oxygen of the NiO 6 octahedra. Doping by Ca improves thermodynamic stability and increases electronic conductivity of Pr 2−x Ca x NiO 4+δ , but decreases oxygen mobility due to decreasing the oxygen excess and appearing of 1-2 additional slow diffusion channels at x ≥ 0.4, probably, due to hampering of cooperative mechanism of migration. However, atomic-scale features of these materials determining oxygen migration require further studies. In this work characteristics of oxygen diffusion in Pr 2−x Ca x NiO 4+δ (x = 0-0.6) are compared with results of the surface analysis by X-ray photoelectron spectroscopy and modeling of the interstitial oxygen migration by the plane-wave density functional theory calculations. According to the X-ray photoelectron spectroscopy data, the surface is enriched by Pr for undoped sample and by Ca for doped ones. The O1s peak at~531 eV corresponding to a weakly bound form of surface oxygen located at Pr cations disappears at~500°C. Migration of interstitial oxygen was modeled for a I4/mmm phase of Pr 2 NiO 4+δ . The interstitial oxygen anion repulses the apical one in the NiO 6 octahedra pushing it into the tetrahedral site between Pr cations. The calculated activation barrier of this migration is equal to 0.585 eV, which reasonably agrees with the experimental value of 0.83 eV obtained by the oxygen isotope exchange method. At the same time, for the model compound Ca 2 NiO 4+δ , obtained by isomorphic substitution of Pr by Ca in Pr 2 NiO 4+δ , calculations implied formation of the peroxide ion comprised of interstitial and lattice oxygen species not revealed in the case of incomplete substitution (up to PrCaNiO 4+δ composition).Hence, calculations in the framework of the plane-wave density functional theory provide a realistic estimation of specificity of oxygen migration features in Pr 2 NiO 4+δ doped by alkaline-earth metals.

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Section: X-ray Photoelectron Spectroscopymentioning

confidence: 78%

Oxygen transport in Pr nickelates: Elucidation of atomic-scale features

et al. 2020

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“…However, the first shoulder like feature VB 1 positioned at ~2.5 eV has appeared mainly due to the hybridization of Tb4f, extended Mn3d_t 2g , and Fe3d_t 2g with O 2p orbitals. However, a significant contribution to this feature VB 1 is expected to be from Tb4f states as the other states (Mn3d_t 2g , Fe3d_t 2g ) are extended over a long range [52]. The most intense feature of the VB spectra at ~ 7 eV (VB 2 ) can be attributed mainly to the hybridization of the Mn3d_t 2g and Fe3d_t 2g orbitals with the O2p states.…”

Section: Resultsmentioning

confidence: 99%

“…The most intense feature of the VB spectra at ~ 7 eV (VB 2 ) can be attributed mainly to the hybridization of the Mn3d_t 2g and Fe3d_t 2g orbitals with the O2p states. On the other hand, the feature VB 3 at the lowest energy ~10.5 eV emanates from the hybridized states of O2p -Mn3d_t 2g / Fe3d_t 2g and other oxygen bonding states O2p-Mn/Fe4sp and O2p-Tb5sd, etc., with significant contribution being from O2p states [52].…”

Section: Resultsmentioning

confidence: 99%

Study of band structure, transport and magnetic properties of BiFeO3–TbMnO3 composite

et al. 2019

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Charge transfer across the interface of two materials in a composite can create reconstruction of bands near the interface which in turn brings multiple changes in physical properties of the materials. Thus, investigation of band structure experimentally is of immense importance in studying composite materials to understand their physical properties. Here, we have studied magnetoelectric multiferroic composite of two types of multiferroic (types I and II) consisting of BiFeO 3 and TbMnO 3 for enhanced magnetic and transport properties. The band structure was investigated with the help of UV-visible absorption spectrum, the valence band X-ray photoemission spectra (XPS), and ultraviolet photoemission spectra. The band structure thus obtained can successfully explain the magnetic and transport properties of the composite. The insulating behavior of the system is understood from the reconstruction of the energy bands at the interface and subsequent decrease in the band gap which happens due to lattice mismatch of the two materials. The large coercivity and the increase in the magnetization value are understood to be due to superexchange interaction between different Mn ions (Mn 2+ , Mn 3+ , and Mn 4+). From the composition study of EDXA and core-level XPS, oxygen vacancy was found which in turn creates the mixed valence state of Mn to maintain the charge neutrality.

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“…1c. The parallel and anti-parallel coupling of the spins of 3s core holes and 3d electrons generate two distinct peaks (high-spin and low-spin state at lower and higher binding energy, respectively) in the Mn-3s spectrum 32,33 . Beyreuther et al 34 derived a linear relationship between the Mn-valence state ( v Mn ) and the exchange splitting ( E 3s ) of the two Mn-3 s peaks, The observed energy splitting (�E 3s = 5.1(5)eV) gives v Mn = 3.2 (5), which is comparable with the expected v Mn = 3.33 for the LP3 compound.…”

mentioning

confidence: 99%

“…The observed valence band offset is ~ 1.1 eV, calculated from the linear regression fit along the leading edge of the valence band spectrum 35,36 . Due to the crystal field effect a distinct feature of the Mn-3d(e g ) orbital is expected 33,35,37 near ~ 0.5 eV in the ferromagnetic region. However, as this VB spectrum was recorded at room temperature (paramagnetic state) the Mn-3d(e g ) state is less pronounced.…”

mentioning

confidence: 99%

Field induced crossover in critical behaviour and direct measurement of the magnetocaloric properties of La0.4Pr0.3Ca0.1Sr0.2MnO3

Ghorai

Skini

Hedlund

et al. 2020

Sci Rep

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La0.4Pr0.3Ca0.1Sr0.2MnO3 has been investigated as a potential candidate for room temperature magnetic refrigeration. Results from X-ray powder diffraction reveal an orthorhombic structure with Pnma space group. The electronic and chemical properties have been confirmed by X-ray photoelectron spectroscopy and ion-beam analysis. A second-order paramagnetic to ferromagnetic transition was observed near room temperature (289 K), with a mean-field like critical behaviour at low field and a tricritical mean-field like behaviour at high field. The field induced crossover in critical behaviour is a consequence of the system being close to a first-order magnetic transition in combination with a magnetic field induced suppression of local lattice distortions. The lattice distortions consist of interconnected and weakly distorted pairs of Mn-ions, where each pair shares an electron and a hole, dispersed by large Jahn–Teller distortions at Mn3+ lattice sites. A comparatively high value of the isothermal entropy-change (3.08 J/kg-K at 2 T) is observed and the direct measurements of the adiabatic temperature change reveal a temperature change of 1.5 K for a magnetic field change of 1.9 T.

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Electronic structure study of wide band gap magnetic semiconductor (La0.6Pr0.4)0.65Ca0.35MnO3 nanocrystals in paramagnetic and ferromagnetic phases

Abstract: Exchange bias and enhanced coercivity in phase separated La0.45Sr0.55MnO3 and Pr0.55(Ca0.65S0.35)

Cited by 10 publications

References 44 publications

Oxygen transport in Pr nickelates: Elucidation of atomic-scale features

Oxygen transport in Pr nickelates: Elucidation of atomic-scale features

Study of band structure, transport and magnetic properties of BiFeO3–TbMnO3 composite

Field induced crossover in critical behaviour and direct measurement of the magnetocaloric properties of La0.4Pr0.3Ca0.1Sr0.2MnO3

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