Two-band model for magnetism and superconductivity in nickelates

Hu, Lun-Hui; Wu, Congjun

doi:10.1103/physrevresearch.1.032046

Cited by 129 publications

(81 citation statements)

References 43 publications

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“…The recent discovery of superconductivity in the Srdoped nickelate NdNiO 2 [1] offers a new exciting platform for investigating unconventional superconductivity in layered correlated materials, thus prompting active theoretical and experimental studies [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Here, one fascinating avenue to explore is computational materials design of new nickelate superconductors exploiting the layered crystal structure.…”

Section: Introductionmentioning

confidence: 99%

Materials design of dynamically stable d9 layered nickelates

et al. 2020

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Motivated by the recent discovery of superconductivity in the Sr-doped layered nickelate NdNiO2, we perform a systematic computational materials design of layered nickelates that are dynamically stable and whose electronic structure better mimics the electronic structure of high-Tc cuprates than NdNiO2. While the Ni 3d orbitals are self-doped from the d 9 configuration in NdNiO2 and the Nd-layer states form Fermi pockets, we find more than 10 promising compounds for which the self-doping is almost or even completely suppressed. We derive effective single-band models for those materials and find that they are in the strongly-correlated regime. We also investigate the possibility of palladate analogues of high-Tc cuprates. Once synthesized, these nickelates and palladates will provide a firm ground for studying superconductivity in the Mott-Hubbard regime of the Zaanen-Sawatzky-Allen classification. arXiv:1910.03974v1 [cond-mat.supr-con]

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Section: Introductionmentioning

confidence: 99%

Materials design of dynamically stable d9 layered nickelates

et al. 2020

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“…A disparate variety of interacting models [1][2][3][4][5][6][7][8][9][10][11][12][13][14] based on density functional theory (DFT) studies [15][16][17][18][19][20][21][22] have been proposed to illuminate the electronic and magnetic behavior underlying the discovery [23] and experimental study [24][25][26] of long-sought superconductivity in a layered nickelate, specifically hole-doped NdNiO 2 (NNO). With the same infinite-layer structure as CaCuO 2 (CCO), which superconducts up to 110 K when doped [27], NNO displays several differences with CCO.…”

Section: Introductionmentioning

confidence: 99%

Fluctuation-frustrated flat band instabilities in NdNiO2

Choi

Pickett

Lee

2020

Phys. Rev. Research

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The discovery that Nd 1−x Sr x NiO 2 , with the CaCuO 2 infinite-layer structure, superconducts up to 15 K around the hole-doping level x = 0.2 raises the crucial question of its fundamental electronic and magnetic processes. The unexplained basic feature that we address is that, for x = 0 and as opposed to strongly antiferromagnetic (AFM) CaCuO 2 , NdNiO 2 with the same structure and formal d 9 configuration does not undergo AFM order. We study this issue not in the conventional manner, as energetically unfavored or as frustrated magnetic order, but as an instability of the AFM phase itself. We are able to obtain the static AFM ordered state, but find that a flat band, one-dimensional-like van Hove singularity (vHs) is pinned to the Fermi level. This situation is unusual in a non-half-filled, effectively two-band system. The vHs makes the AFM phase unstable to spindensity disproportionation, breathing, and half-breathing lattice distortions, and (innate or parasitic) chargedensity disproportionation. These flat band instabilities, distant relatives of single-band cuprate models, thereby inhibit but do not eliminate incipient AFM tendencies at low temperature. The primary feature is that a pair of active bands (d x 2 −y 2 , d z 2) eliminate half-filled physics and, due to instabilities, preclude the AFM phase seen in CaCuO 2. This strongly AFM correlated, conducting spin-liquid phase with strong participation of the Ni d z 2 orbital forms the platform for superconductivity in NdNiO 2 .

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“…Recently, superconductivity was observed at 9 -15 K in the strontium doped infinite-layer nickelate thin films of Nd0.8Sr0.2NiO2 on SrTiO3 substrate [18] . This work has stimulated enormous interests, and plenty of theoretical works have been carried out [19][20][21][22][23][24][25][26][27][28][29][30][31] . Among them, Zhang et al propose the parent compound of Nd0.8Sr0.2NiO2 as a self-doped Mott insulator [26] .…”

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Absence of superconductivity in bulk Nd1−xSrxNiO2

et al. 2020

Commun Mater

167

126

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Recently superconductivity at 9 -15 K was discovered in an infinite-layer nickelate (Nd0.8Sr0.2NiO2 films), which has received enormous attention.Since the Ni 1+ ionic state in NdNiO2 may have the 3d 9 outer-shell electronic orbit which resembles that of the cuprates, it is very curious to know whether superconductivity discovered here has similar mechanism as that in the cuprates. By using a three-step method, we successfully synthesize the bulk samples of Nd1-xSrxNiO2 (x = 0, 0.2, 0.4). The X-ray diffractions reveal that all the samples contain mainly the infinite layer phase of 112 with some amount of segregated Ni. This has also been well proved by the SEM image and the EDS composition analysis. The resistive measurements on the Sr doped samples show insulating behavior without the presence of superconductivity. Temperature dependence of the magnetic moment under high magnetic fields exhibits a Curie-Weiss law feature with the paramagnetic moment of about 2B/f.u.. By applying pressure on Nd0.8Sr0.2NiO2 up to about 50.2 GPa, we find that the strong insulating behavior at ambient pressure is significantly suppressed, but superconductivity has not been observed either. Since the lattice constants derived from our XRD data are very close to those of the reported superconducting films, we argue that the superconductivity in the reported film may not originate from the expected Nd0.8Sr0.2NiO2, but arise from the interface or the stress effect.Since the discovery of high critical temperature superconductivity (HTS) in cuprates in 1986 [1] , there are plenty of experimental and theoretical studies to explore the intrinsic mechanism for superconductivity [2][3][4][5] . There is a general agreement that the parent compound of cuprates like La2CuO4 is a Mott insulator with a charge transfer gap and long-range antiferromagnetic (AF) order [6] . With chemical doping, the long-range AF order will be suppressed at a hole doping level (p  0.02) and d-wave superconductivity emerges at a higher doping level (p  0.05) [7][8][9] . After the efforts more than three decades, some common features have been observed, although the intrinsic pairing mechanism of HTS remains unresolved yet. These include two-dimensional electronic structure and coexistence with an AF order or spin fluctuations, all these also occur in most iron-based [10] and heavy fermion superconductors [11] .Moreover, in cuprates, it is also important that the spin S = 1/2 magnetic moment from 3d 9 electrons form the basic structure of the AF order. One intuitive way to explore the pairing mechanism of cuprates is to find additional high-TC superconductors with different transition metals but similar crystal and

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Two-band model for magnetism and superconductivity in nickelates

Cited by 129 publications

References 43 publications

Materials design of dynamically stable d9 layered nickelates

Materials design of dynamically stable d9 layered nickelates

Fluctuation-frustrated flat band instabilities in NdNiO2

Absence of superconductivity in bulk Nd1−xSrxNiO2

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