Electron doped layered nickelates: Spanning the phase diagram of the cuprates

The search for oxide materials with physical properties similar to the cuprate high Tc superconductors, but based on alternative transition metals such as nickel, has grown and evolved over time [1][2][3][4][5][6][7][8][9][10]. The recent discovery of superconductivity in doped infinite-layer nickelates RNiO2 (R = rare-earth element) [11,12] further strengthens these efforts. With a crystal structure similar to the infinite-layer cupratestransition metal oxide layers separated by a rare-earth spacer layerformal valence counting suggests that these materials have monovalent Ni 1+ cations with the same 3d electron count as Cu 2+ in the cuprates. Here, we use x-ray spectroscopy in concert with density functional theory to show that the electronic structure of RNiO2 (R = La, Nd), while similar to the cuprates, includes significant distinctions. Unlike cuprates with insulating spacer layers between the CuO2 planes, the rare-earth spacer layer in the infinite-layer nickelate supports a weaklyinteracting three-dimensional 5d metallic state. This three-dimensional metallic state hybridizes with a quasi-two-dimensional, strongly correlated state with 3dx 2 -y 2 symmetry in the NiO2 layers. Thus, the infinite-layer nickelate can be regarded as a sibling of the rare earth intermetallics [13-15], well-known for heavy Fermion behavior, where the NiO2 correlated layers play an analogous role to the 4f states in rare-earth heavy Fermion compounds. This unique Kondo-or Anderson-lattice-like "oxide-intermetallic" replaces the Mott insulator as the reference state from which superconductivity emerges upon doping.While the mechanism of superconductivity in the cuprates remains a subject of intense research, early on it was suggested that the conditions required for realizing high Tc superconductivity are rooted in the physics of a two-dimensional electron system subject to strong local repulsion [16,17]. This describes the Mott (charge-transfer) insulators in the stoichiometric parent compounds, characterized by spin ½ Heisenberg antiferromagnetism, from which superconductivity emerges upon doping. A long-standing question regards whether these "cuprate-Mott" conditions can be realized in other oxides; and extensive efforts to synthesize and engineer nickel oxides (nickelates) have promised such a realization [1-10]. Infinite-layer NdNiO2 became the first such nickelate superconductor following the recent discovery of superconductivity in Srdoped samples [11]. The undoped parent compound, produced by removing the apical oxygen atoms from the perovskite nickelate NdNiO3 using a metal hydride-based soft chemistry reduction process [10,[18][19][20], appears to be a close sibling of the cuprates-it is isostructural to the infinitelayer cuprates with monovalent Ni 1+ cations and possesses the same 3d 9 electron count as that of Cu 2+ cations in undoped cuprates. Yet, as we will reveal, the electronic structure of the undoped RNiO2 (R = La and Nd) remains distinct from the Mott, or charge-transfer, compounds of undoped cuprates, and even...

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confidence: 99%

Electronic structure of the parent compound of superconducting infinite-layer nickelates

et al. 2020

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“…We chose Th over Ce to avoid dealing with f states and because Ce has two plausible oxidation states (3+ and 4+). Here, an AFM state could be stabilized within LDA+U , but a gap cannot be opened regardless of the U value due to the much stronger hybridization of Pd-d and Th-d states as compared to the nickelate [28]. Though this metallic AFM state is more stable than a FM one by 27 meV/Pd for U =3.5 eV, this energy difference is one order of magnitude smaller than in the nickelate.…”

Section: La4pd3o8: Trilayermentioning

confidence: 87%

“…To explore this further, we investigated whether a magnetic state could be obtained. Previously, we had been able to stabilize magnetic solutions for La 4 Ni 3 O 8 and Pr 4 Ni 3 O 8 if we include an on-site Coulomb U [9,27,28]. In the 438 phases, the average Ni/Pd valence is +1.33 which leaves the e g orbitals with 2.67 electrons per Ni/Pd on average.…”

Section: La4pd3o8: Trilayermentioning

confidence: 99%

Layered palladates and their relation to nickelates and cuprates

Botana

Norman

2018

Phys. Rev. Materials

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We explore the layered palladium oxides La2PdO4, LaPdO2 and La4Pd3O8 via ab initio calculations. La2PdO4, being low spin d 8 , is quite different from its high spin nickel analog. Hypothetical LaPdO2, despite its d 9 configuration, has a paramagnetic electronic structure very different from cuprates. On the other hand, the hypothetical trilayer compound La4Pd3O8 (d 8.67 ) is more promising in that its paramagnetic electronic structure is very similar to that of overdoped cuprates. But even in the d 9 limit (achieved by partial substitution of La with a 4+ ion), we find that an antiferromagnetic insulating state cannot be stabilized due to the less correlated nature of Pd ions. Therefore, this material, if it could be synthesized, would provide an ideal platform for testing the validity of magnetic theories for high temperature superconductivity.

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“…5 Nonetheless, layered nickelates exhibit a number of intriguing physical properties and phase transitions. [6][7][8] For example, trilayered perovskite R 4 Ni 3 O 10 compounds are members of a small family of oxides that exhibit metallic conductivity even at low temperatures. 9 Interesting, these compounds undergo a metal-to-metal transition between 140 K and 165 K. [9][10][11] Recently, Li et al 11 analyzed the Fermi surface of the trilayer nickelate La 4 Ni 3 O 10 using angle-resolved photoemission spectroscopy (ARPES) and density functional theory (DFT) band structure calculations.…”

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confidence: 99%

Crystal structure stability and electronic properties of the layered nickelate La4Ni3O10

Puggioni

Rondinelli

2018

Phys. Rev. B

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We investigate the crystal structure and the electronic properties of the trilayer nickelate La4Ni3O10 by means of quantum mechanical calculations in the framework of the density functional theory. We find that, at low temperature, La4Ni3O10 undergoes a hitherto unreported structural phase transition and transforms to a new monoclinic P 21/a phase. This phase exhibits electronic properties in agreement with recent angle-resolved photoemission spectroscopy data reported in H. Li et al., Nat. Commun. 8, 704 (2017) and should be considered in models focused on explaining the observed ∼140 K metal-to-metal phase transition.

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Electron doped layered nickelates: Spanning the phase diagram of the cuprates

Cited by 62 publications

References 39 publications

Electronic structure of the parent compound of superconducting infinite-layer nickelates

Electronic structure of the parent compound of superconducting infinite-layer nickelates

Layered palladates and their relation to nickelates and cuprates

Crystal structure stability and electronic properties of the layered nickelate La4Ni3O10

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