Resisitivity, thermopower, and susceptibility of<i>R</i><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">NiO</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>(<i>R</i>=La,Pr)

Xu, Xue Qing; Peng, J. L.; Li, Z. Y.; Ju, Honglyoul; Greene, R. L.

doi:10.1103/physrevb.48.1112

Cited by 121 publications

(69 citation statements)

References 22 publications

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“…In bulk equilibrium form, this material is an exception among the RNiO 3 family since it remains a paramagnetic metal down to the lowest temperatures. 9,10 This metal has a rather high degree of electronic correlations, however, as signaled by the enhancement of the effective mass and susceptibility as compared to band values, as well as the sizable T 2 coefficient of the resistivity. [10][11][12][13] One may thus expect that this material can be rather easily tuned to become an insulator.…”

Section: Introductionmentioning

confidence: 99%

“…9,10 This metal has a rather high degree of electronic correlations, however, as signaled by the enhancement of the effective mass and susceptibility as compared to band values, as well as the sizable T 2 coefficient of the resistivity. [10][11][12][13] One may thus expect that this material can be rather easily tuned to become an insulator. Indeed, ultrathin LNO films were shown to become insulating under either dimensionality control 6,14,15 or epitaxial strain.…”

Section: Introductionmentioning

confidence: 99%

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Orbital polarization in strainedLaNiO3: Structural distortions and correlation effects

2014

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Transition-metal heterostructures offer the fascinating possibility of controlling orbital degrees of freedom via strain. Here, we investigate theoretically the degree of orbital polarization that can be induced by epitaxial strain in LaNiO3 films. Using combined electronic structure and dynamical mean-field theory methods we take into account both structural distortions and electron correlations and discuss their relative influence. We confirm that Hund's rule coupling tends to decrease the polarization and point out that this applies to both the d 8 L and d 7 local configurations of the Ni ions. Our calculations are in good agreement with recent experiments, which revealed sizable orbital polarization under tensile strain. We discuss why full orbital polarization is hard to achieve in this specific system and emphasize the general limitations that must be overcome to achieve this goal.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Orbital polarization in strainedLaNiO3: Structural distortions and correlation effects

2014

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“…Among these materials, LaNiO 3 (LNO), a metal and paramagnet lacking any ordering phenomena in bulk [1][2][3], has recently become the subject of intense research. This was mainly triggered by theoretical work [4] which suggested the possibility of orbital ordering and high-T c superconductivity in superlattices where very thin LNO layers are separated by insulating layers, confining the conduction to two dimensions (2D).…”

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confidence: 99%

Metal-Insulator Transition in UltrathinLaNiO3Films

et al. 2011

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Transport in ultrathin films of LaNiO3 evolves from a metallic to a strongly localized character as the film's thickness is reduced and the sheet resistance reaches a value close to h/e 2 , the quantum of resistance in two dimensions. In the intermediate regime, quantum corrections to the Drude lowtemperature conductivity are observed; they are accurately described by weak localization theory. Remarkably, the negative magnetoresistance in this regime is isotropic, which points to magnetic scattering associated with the proximity of the system to either a spin glass state or the charge ordered antiferromagnetic state observed in other rare earth nickelates.Complex oxides are exciting materials in which the interplay between charge, spin, orbital and lattice degrees of freedom leads to a wealth of novel and exotic phenomena. Among these materials, LaNiO 3 (LNO), a metal and paramagnet lacking any ordering phenomena in bulk [1][2][3], has recently become the subject of intense research. This was mainly triggered by theoretical work [4] which suggested the possibility of orbital ordering and high-T c superconductivity in superlattices where very thin LNO layers are separated by insulating layers, confining the conduction to two dimensions (2D). These predictions have yet to be confirmed experimentally. LNO bulk and thin films have been extensively studied in the past, showing a large effective mass and enhanced Pauli paramagnetism, which has been attributed to strong correlations [1,2,5]. This material has also been reported to be sensitive to the degree of disorder. For instance, increasing the amount of oxygen vacancies can lead to weak localization and metal-insulator (MI) transitions, as well as antiferromagnetic ordering and spin glass behaviour [6][7][8]. LNO based heterostructures have been grown and transport measurements have revealed a MI transition as the LNO thickness is reduced to only a few unit cells (u.c.) [9,10]. This behaviour is in agreement with the MI transition observed in single ultrathin LNO films [11]. Understanding the nature of transport for this compound in the ultrathin limit appears essential for future investigation of LNO-based heterostructures and serves as the motivation for this work. Upon reduction of the LNO thickness, transport evolves from a metallic to a strongly localized behavior as the room temperature sheet resistance approaches h/e 2 ∼ 25 kΩ, the quantum of resistance in 2D. We find a transition region between the metallic and the strongly localized states where the films show an upturn in the resistivity at low temperatures which can be explained by the theory of weak localization. Surprisingly, the magnetoresistance (MR) is found to be isotropic in this regime. We attribute this to the presence of magnetic scattering and discuss its possible origins. Films were grown on (001) SrTiO 3 substrates by off-axis rf magnetron sputtering, leading to fully strained epi-

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“…Figure 3(b) shows the thermopower of LaRh 1−x Ni x O 3 from 4.2 to 800 K. After the thermopower drastically deareases from x = 0 to 0.05, it gradually decreases with x above x = 0.1. We should note that the sign is always positive for all the samples, which further excludes the possible existence of Ni 3+ ions giving negative thermopower [21]. We observe large thermopower up to 800 K, which suggests that Rh ions are in the low-spin state up to high temperature.…”

Section: +mentioning

confidence: 55%

Thermoelectric properties of LaRh_1−xNi_xO₃

Shibasaki

Takahashi

Terasaki

2009

J. Phys.: Condens. Matter

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Abstract. We report measurements and analyses of resistivity, thermopower, and thermal conductivity of polycrystalline samples of perovskite LaRh 1−x Ni x O 3 . The thermopower is found to be large at 800 K (185 µV/K for x =0.3), which is ascribed to the high-temperature stability of the low-spin state of Rh 3+ /Rh 4+ ions. This clearly contrasts with the thermopower of the isostructural oxide LaCoO 3 , which rapidly decreases above 500 K owing to the spin-state transition. The spin state of the transition-metal ions is one of the most important parameters in oxide thermoelectrics.

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Resisitivity, thermopower, and susceptibility ofRNiO3(R=La,Pr)

Cited by 121 publications

References 22 publications

Orbital polarization in strainedLaNiO3: Structural distortions and correlation effects

Orbital polarization in strainedLaNiO3: Structural distortions and correlation effects

Metal-Insulator Transition in UltrathinLaNiO3Films

Thermoelectric properties of LaRh_1−xNi_xO₃

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Resisitivity, thermopower, and susceptibility ofRNiO3(R=La,Pr)

Cited by 121 publications

References 22 publications

Orbital polarization in strainedLaNiO3: Structural distortions and correlation effects

Orbital polarization in strainedLaNiO3: Structural distortions and correlation effects

Metal-Insulator Transition in UltrathinLaNiO3Films

Thermoelectric properties of LaRh1−xNixO3

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Thermoelectric properties of LaRh_1−xNi_xO₃