Disorder Effects in Electronic Structure of Substituted Transition Metal Compounds

Sarma, D. D.; Chainani, A.; Krishnakumar, S.; Vescovo, E.; Carbone, C.; Eberhardt, W.; Rader, O.; Jung, Ch.; Hellwig, Ch.; Gudat, W.; Srikanth, H.; Raychaudhuri, A. K.

doi:10.1103/physrevlett.80.4004

Cited by 82 publications

(52 citation statements)

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“…The mean hopping distance R h (T) and hopping energy E h (T) at a given temperature T could also be estimated in terms of T 0 and localization length as given by [59] …”

Section: Electrical Conductivity and Transport Propertiesmentioning

confidence: 99%

Synthesis, Characterization, Optical and Transport Properties of BaSnO<SUB>3</SUB> Synthesized by Wet Chemical Route

Kurre¹,

Bajpai²,

Bajpai³

2018

MSA

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Alkaline earth stannates have renewed attention as potential materials for gas sensing, transparent conducting oxides and ceramic capacitor applications. A noble wet chemical route is chosen to synthesize BaSnO 3 powders having micron size grains. Problems related to uneven grains and poor densification in conventional solid state route have been overcome in the present method. X-ray diffraction data confirms the single phase formation without any secondary phase having cubic perovskite structure (S.G. Pm-3 m). The estimated lattice parameter is ≈4.11933 Ǻ and percentage density is ≈90%. The microstructure probed by scanning electron micrograph reveals almost homogeneously distributed particles having random shape with some porosity. Phonon modes in FT-IR and Raman spectra confirm the local symmetry distortion. The DC conductivity at 200˚C approaches almost 2 × 10 −2 (Ω-cm) −1 , which is almost of the same order as that observed in perovskite based electronic conductors. DC and a.c. electrical conductivity of the material follow Mott's variable range hopping at low temperature and Arrhenius type thermally activated process at elevated temperatures. Evidence of small polar on formation is also verified. Optical band gap estimated from absorption data is ≈2.94 very close to the reported value. Composition prepared through the noble wet chemical route has high electrical conduction and suitable for gas sensing applications.

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“…The mean hopping distance R h (T) and hopping energy E h (T) at a given temperature T could also be estimated in terms of T 0 and localization length as given by [59] …”

Section: Electrical Conductivity and Transport Propertiesmentioning

confidence: 99%

Synthesis, Characterization, Optical and Transport Properties of BaSnO<SUB>3</SUB> Synthesized by Wet Chemical Route

Kurre¹,

Bajpai²,

Bajpai³

2018

MSA

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“…These plots reveal that the data fit very well with the VRH model in the entire temperature range of measurement, suggesting the conduction to be governed by the disorder induced localization of charge carriers. 17 We also observe that with increase in the Ni concentration, the slope of the curve decreases. This further confirms that Ni substitution in LaFeO 3 decreases the activation energy or overall hopping potential via carrier doping.…”

mentioning

confidence: 58%

“…The carriers in the localized states move by a phenomenon known as variable-range hopping ͑VRH͒. 17 In order to understand the effect of disorder induced localization on the electrical transport behavior, we have fit our data with Mott's VRH model ͑T͒ = 0 exp͑T 0 / T 1/4 ͒ in the measured temperature range of 77 to 300 K. Figure 2͑b͒ shows the ln versus T −1/4 plot for all the samples. These plots reveal that the data fit very well with the VRH model in the entire temperature range of measurement, suggesting the conduction to be governed by the disorder induced localization of charge carriers.…”

mentioning

confidence: 99%

“…[15][16][17][18] It is suggested that in these systems the MI transition is due to the potential mismatch between the substituent metal ion and Ni +3 ion, which causes the transfer of hole states from near E F to an energy state above E F . Most of these observations have been made on polycrystalline bulk samples, where the contribution from grain boundaries could not be avoided.…”

mentioning

confidence: 99%

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Exposition of semiconducting and ferromagnetic properties of pulsed-laser-deposited thin films of LaFe1−xNixO3 (x=0.3, 0.4, and 0.5)

Choudhary¹,

Kumar²,

Khan

et al. 2005

Applied Physics Letters

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We have explored the possibility of ferromagnetic semiconducting property in the epitaxial thin films of LaFe 1−x Ni x O 3 ͑x = 0.3, 0.4, and 0.5͒ grown on ͑001͒ oriented LaAlO 3 substrate. We observe that substitution of Ni in the series leads to the increase in conductivity of the samples with conduction being controlled by the disorder-induced localization of charge carriers. All these samples show ferromagnetic behavior at room temperature while their magnetization decreases with increase in Ni concentration in the composition. The results have been explained on the basis of the close interplay between the electrical and magnetic properties. © 2005 American Institute of Physics. ͓DOI: 10.1063/1.2058218͔Over the last few years, there has been extensive study in the direction of search for the materials possessing ferromagnetic property as well as the semiconducting property because of their potential applications in the spintronics devices, wherein the spin-controlled electrical, optical, and magnetic properties are desired. 1,2 The study has yielded several systems such as magnetic multilayers, 3 Fe 3 O 4 , 4 perovskite-based transition metal oxides etc. 5 Study of transition metal oxides ͑TMOs͒, has revealed an impressive diversity of exciting physical properties such as dielectric, magnetic, optical, and transport properties because of the strong electron correlation effect in the system. The TMOs exhibit high-T c superconductivity in cuprate systems; metalinsulator ͑MI͒ transition, colossal magnetoresistance, and charge ordering in manganites; and many other phenomena in other TMO systems. [5][6][7][8] Among several TMO-based systems of LaTO 3 ͑T = Fe, Co, Cr, Ni, and Mn͒, LaNiO 3 has rhombohedral perovskite structure and is a Pauli-paramagnetic metal with high electrical conductivity at room temperature, 9 while the other TMO systems are generally antiferromagnetic insulators, except for LaFeO 3 , which shows ferrimagnetic transition at Néel temperature T N ϳ 750 K. 10-14 Therefore, the series of LaNi 1−x Fe x O 3 samples provides an ideal opportunity to observe an interesting co-occurrence of MI transition accompanied with a paramagnetic to ferrimagnetic transition in the same member of the series at a critical substitution concentration of Fe/ Ni ions. This presents a prospect to investigate the Mott's criterion of the dependence of MI transition on the critical charge carrier density by examining in such series from its one end member ͑LaNiO 3 ͒ to the one at the other end ͑LaFeO 3 ͒.There are several reports available on bulk samples of LaNi 1−x Fe x O 3 series by various groups including ours, where disorder-induced MI transition, structural transition from rhombohedral ͑LaNiO 3 ͒ to orthorhombic ͑LaFeO 3 ͒ at Fe concentration of ϳ50%, and the inverse dependence of itinerancy of d electrons with the Fe concentration have been observed. [15][16][17][18] It is suggested that in these systems the MI transition is due to the potential mismatch between the substituent metal ion and Ni +3 ion, which cause...

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“…We find that α = 0.5±0.05 provides a good description of the spectra for both CaRuO 3 and SrRuO 3 for BE > 2k B T suggesting an influence of disorder in the electronic structure as also observed in other oxides [15,16]. Interestingly, the full width at half maximum (FWHM) of the Gaussian needed to simulate the experimental spectra is significantly large compared to 1.4 meV expected from the instrument resolution function.…”

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confidence: 81%

Observation of particle hole asymmetry and phonon excitations in non-Fermi-liquid systems: A high-resolution photoemission study of ruthenates

Maiti¹,

Singh²,

Medicherla³

2007

Europhys. Lett.

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PACS. 71.10.Hf -Non Fermi liquid ground states, electron phase diagrams and phase transitions in model systems. PACS. 63.20.Kr -Phonon -electron and phonon -phonon interactions. PACS. 71.45.Gm -Exchange, correlation, dielectric and magnetic response functions, plasmons.Abstract. -We investigate the temperature evolution of the electronic states in the vicinity of the Fermi level of a non-Fermi liquid (NFL) system, CaRuO3 using ultra high-resolution photoemission spectroscopy; isostructural SrRuO3 exhibiting Fermi liquid behavior despite similar electron interaction parameters as that of CaRuO3, is used as a reference. High-energy resolution in this study helps to reveal particle-hole asymmetry in the excitation spectra of CaRuO3 in contrast to that in SrRuO3. In addition, we observe signature of phonon excitations in the photoemission spectra of CaRuO3 at finite temperatures while these are weak in SrRuO3.Recent observations of various bulk properties in normal phase of high temperature superconductors [1], d and f electrons at quantum critical points [2], low dimensional systems [3] etc., exhibit deviations from Fermi-liquid (FL) behavior, the most fundamental paradigm in solid-state physics [4]. Such non-Fermi liquid (NFL) behavior has often been attributed to strong electron correlations and/or charge fractionalizations [5]. Interestingly, CaRuO 3 , a 3-dimensional orthorhombically distorted perovskite exhibits NFL behavior at low temperatures, while isostructural SrRuO 3 exhibits Fermi liquid (FL) behavior [6]. Magnetic measurements reveal ferromagnetic ground state in SrRuO 3 (Curie temperature, T C ∼ 165 K). However, CaRuO 3 does not exhibit long range order.The average Ru-O-Ru bond angle is slightly different in these two compounds (150 • in CaRuO 3 and 165• in SrRuO 3 ). It was believed that the decrease in the electron hopping interaction strength, t, due to smaller Ru-O-Ru angle in CaRuO 3 leads to an increase in effective electron correlation strength, U/W (U = electron-electron Coulomb repulsion strength, t ∝ W ∼ bandwidth), and hence the NFL behavior appears in CaRuO 3 [6]. However, a recent study based on band structure calculation and photoemission spectroscopy [7] shows that the width of various d-bands remains almost the same across the series and U/W is essentially ( * ) Corresponding author: kbmaiti@tifr.res.in c EDP Sciences

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Disorder Effects in Electronic Structure of Substituted Transition Metal Compounds

Cited by 82 publications

References 31 publications

Synthesis, Characterization, Optical and Transport Properties of BaSnO<SUB>3</SUB> Synthesized by Wet Chemical Route

Synthesis, Characterization, Optical and Transport Properties of BaSnO<SUB>3</SUB> Synthesized by Wet Chemical Route

Exposition of semiconducting and ferromagnetic properties of pulsed-laser-deposited thin films of LaFe1−xNixO3 (x=0.3, 0.4, and 0.5)

Observation of particle hole asymmetry and phonon excitations in non-Fermi-liquid systems: A high-resolution photoemission study of ruthenates

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Disorder Effects in Electronic Structure of Substituted Transition Metal Compounds

Cited by 82 publications

References 31 publications

Synthesis, Characterization, Optical and Transport Properties of BaSnO&lt;SUB&gt;3&lt;/SUB&gt; Synthesized by Wet Chemical Route

Synthesis, Characterization, Optical and Transport Properties of BaSnO&lt;SUB&gt;3&lt;/SUB&gt; Synthesized by Wet Chemical Route

Exposition of semiconducting and ferromagnetic properties of pulsed-laser-deposited thin films of LaFe1−xNixO3 (x=0.3, 0.4, and 0.5)

Observation of particle hole asymmetry and phonon excitations in non-Fermi-liquid systems: A high-resolution photoemission study of ruthenates

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Synthesis, Characterization, Optical and Transport Properties of BaSnO<SUB>3</SUB> Synthesized by Wet Chemical Route

Synthesis, Characterization, Optical and Transport Properties of BaSnO<SUB>3</SUB> Synthesized by Wet Chemical Route