Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session X43: Electronic, Magnetic, and Structural Properties of NickelatesLive
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Sponsoring Units: DCMP Chair: Trinanjan Datta, Augusta University |
Friday, March 19, 2021 8:00AM - 8:12AM Live |
X43.00001: Electronic structure and magnetism in infinite-layer nickelates RNiO2 (R= La-Lu) Jesse Kapeghian, Antia Botana Using first-principles calculations, we analyze the evolution of the electronic structure and magnetic properties of infinite-layer nickelates RNiO2 (R= rare-earth) as R changes across the lanthanide series from La to Lu. By correlating these changes with in-plane and out-of-plane lattice parameter reductions, we conclude that the in-plane Ni-O distance is the relevant control parameter in infinite-layer nickelates. An antiferromagnetic ground state is obtained for all RNiO2 (R=La-Lu). This antiferromagnetic state remains metallic across the lanthanide series and is defined by a multiorbital picture with low-energy relevance of a flat Ni-dz2 band pinned at the Fermi level, in contrast to cuprates. Other non-cuprate-like properties such as the involvement of R-d bands at the Fermi level and a large charge transfer energy are robust for all RNiO2 materials. |
Friday, March 19, 2021 8:12AM - 8:24AM Live |
X43.00002: Many body electronic structure of infinite layer and trilayer nickelates Jonathan Karp, Alexander Hampel, Manuel Zingl, Antia Botana, Hyowon Park, Michael Ray Norman, Andrew Millis Motivated by recent experiments on infinite layer (RNiO2) and trilayer (R4Ni3O8) nickelate analogs of cuprate superconductors, we use a combination of density functional and dynamical mean field (DFT+DMFT) methods to perform a comparative study many body electronic structure of these materials, with a focus on CaCuO2, NdNiO2, and Pr4Ni3O8. We find that the correlated Ni-3d shells of both families of nickelates have similar many-body configurations. Additionally, when compared at the same nominal carrier concentration, the materials exhibit similar many-body electronic structures, self energies, and correlation strengths. Compared to cuprates, the nickelates are closer to the Mott-Hubbard regime due to their larger charge transfer energies. Moreover, doping involves the charge reservoir provided by the rare earth 5d electrons, as opposed to cuprates where it is realized via the oxygen 2p electrons. Like cuprates, the correlations in the nickelates are dominated by a dx2-y2 and O-pσ hybrid. Differences between the two families of nickelates can be attributed to the lack of c-axis dispersion in the trilayer nickelates, leading to differences in Fermiology that may be the primary driver of differences in material properties. |
Friday, March 19, 2021 8:24AM - 8:36AM Live |
X43.00003: Electronic and structural changes in SmNiO3 perovskite under doping with hydrogen Ivan Zaluzhnyy, Peter Oliver Sprau, Richard Tran, Qi Wang, Hai-Tian Zhang, Zhen Zhang, Nelson Hua, Boyan Stoychev, Mathew J Cherukara, Martin Holt, Evgeny Nazarertski, Xiaojing Huang, Hanfei Yan, Ajith Pattammattel, Yong S. Chu, Shyue Ping Ong, Shriram Ramanathan, Oleg Shpyrko, Alex Frano Doping with hydrogen leads to formation of a new insulating phase in rare-earth nickelates, such as SmNiO3. High mobility of hydrogen atoms inside the perovskite crystal lattice allows one to change the distribution of hydrogen by applying short voltage pulses. The memory nano-devices based on this effect are promising candidates for creations of artificial synapses for neuromorphic computing. |
Friday, March 19, 2021 8:36AM - 8:48AM Live |
X43.00004: Electronic structure and magnetic properties of higher-order layered nickelates: Lan+1NinO2n+2 (n = 4 - 6) Harrison LaBollita, Antia Botana The recent discovery of superconductivity in Sr-doped NdNiO2, with a critical temperature of 10-15 K suggests the possibility of a new family of nickel-based high-temperature superconductors (HTS). NdNiO2 is the n = ∞ member of a larger series of layered nickelates with chemical formula Rn+1NinO2n+2 (R = La, Nd, Pr; n = 2, 3, ...,∞). The n = 3 member has been experimentally and theoretically shown to be cuprate-like and a promising HTS candidate if electron doping could be achieved. The higher-order n = 4, 5, and 6 members of the series fall directly into the cuprate dome area of filling without the need of doping, thus making them very promising candidates for HTS, but have not been synthesized yet. Here, we perform first-principles calculations on hypothetical n = 4, 5, and 6 structures to gain a complete theoretical description of their electronic and magnetic properties and compare them with the known n = ∞ and n = 3 materials. From our calculations, we find that the cuprate-like character of layered nickelates increases from the n = ∞ to the n = 3 members as the charge transfer energy and the self-doping effect due to R-d bands around the Fermi level gradually decrease. |
Friday, March 19, 2021 8:48AM - 9:00AM Live |
X43.00005: Hund's metal physics: from SrNiO2 to LaNiO2 Yilin Wang, Changjong Kang, Hu Miao, Gabriel Kotliar We study the normal state electronic structure of the recently discovered infinite-layer nickelate superconductor, Nd1-xSrxNiO2, using DFT+DMFT calculations. Starting with the multi-orbital compound SrNiO2, our calculations show that despite large charge carrier doping from SrNiO2 to LaNiO2, the Ni-3d total occupancy is barely changed due to the decreased hybridization with the occupied oxygen-2p states and increased hybridization with the unoccupied La-5d states. Thus, using SrNiO2 as a reference, La1-xSrxNiO2 is naturally and conclusively found to be a multi-orbital electronic system with characteristic Hund's metal behaviors, such as metallicity, the importance of high-spin configurations, tendency towards orbital differentiation, and the absence of magnetism in regimes which are ordered according to static mean-field theories. Our results are in good agreement with the existing spectroscopic studies and make an essential step towards understanding of the electronic structures of Nd1-xSrxNiO2. |
Friday, March 19, 2021 9:00AM - 9:12AM Live |
X43.00006: Infinite-layer nickelates as Ni eg Hund’s metals Byungkyun Kang, Corey Melnick, patrick Sémon, Gabriel Kotliar, Sangkook Choi The recent and exciting discovery of superconductivity in the hole-doped infinite-layer nickelate Nd1-xSrxNiO draws strong attention to unconventional superconductivity. From a theoretical view point, this new class of unconventional superconducting materials provide an opportunity to unveil new physics in correlated quantum materials. Here we study the temperature and doping dependence of the local spectrum of the charge, spin and orbital susceptibilities from first principles. By using ab initio LQSGW+DMFT methodology, we show that onsite Hund's coupling in Ni d orbitals gives rise to multiple signatures of Hund's metallic phase in Ni d subshell. Interestingly, we found that this Hundness is only evident in the Ni eg orbitals and not the Ni t2g orbitals. In this material, the most occupied state (in each subspace with the same total charge) is the one with the maximum Ni eg spin and Ni t2g orbitals are inactive. Our finding unveils a new feature of the Hund’s metals and has potential implications for the broad range of correlated two orbital systems away from half-filling. |
Friday, March 19, 2021 9:12AM - 9:24AM Live |
X43.00007: Structural signatures of the insulator-to-metal transition in BaCo1-xNixS2 Emily C Schueller, Kyle Miller, William Zhang, Julia Zuo, James M Rondinelli, Stephen D Wilson, Ram Seshadri The solid solution BaCo1-xNixS2 exhibits an insulator-to-metal transition close to x = 0.21. The questions of whether this transition is coupled with structural changes remain unresolved. X-ray diffraction data reveal significant basal sulfide anion displacements occurring preferentially along the CoS5 pyramidal edges comprising the edge-connected bond network in BaCo1-xNixS2. These displacements decrease in magnitude as x increases and are nearly quenched in x = 1 BaNiS2. Here we present density functional theory-based electronic structure calculations on x = 0 BaCoS2 and show that these displacements arise as a dynamic first-order Jahn-Teller effect owing to partial occupancy of nominally degenerate Co2+ dxz and dyz orbitals. This Jahn-Teller instability leads to local structural symmetry breaking associated with opening a band gap that is further strengthened by electronic correlation. The Jahn-Teller effect is reduced upon increased electron filling as x → 1, indicating local structure and band filling cooperatively induce the observed insulator-to-metal transition.1 |
Friday, March 19, 2021 9:24AM - 9:36AM Live |
X43.00008: Fluence dependent structural changes in photoexcited NdNiO3 thin films Jugal Mehta, Jianheng Li, Scott Smith, Rahul Jangid, Nadia Albayati, Kenneth Ainslie, Donald A Walko, Haidan Wen, Roopali Kukreja Rare earth nickelates display metal-insulator transition which is accompanied by a magnetic transition, charge ordering, and a crystal structure change from orthorhombic to monoclinic. Laser-induced excitation drives the transition at ultrafast timescales and can be used in combination with time resolved x-ray diffraction to disentangle the contribution of competing degrees of freedom. In this study, we focused on measuring the laser fluence dependent photoinduced structural response of epitaxial NdNiO3/ SrTiO3 thin films(NNO/STO) of 9 nm and 19 nm thickness. We utilized time-resolved x-ray diffraction to observe the evolution of the out of plane (002)pc Bragg peak and the in-plane (1-13)/2pc Bragg peak of NNO after laser excitation. Our measurement shows a contraction of the out of plane lattice parameter for low fluences and expansion for high fluences after laser excitation. The observed sign reversal of the peak shift requires a fluence threshold in the range of 1.8-2.4 mJ/cm2 for both films. We observe a thermally inaccessible state for higher laser fluences which recovers with a time constant of 200 ps. |
Friday, March 19, 2021 9:36AM - 9:48AM Not Participating |
X43.00009: Critical Self Organization of Antiferromagnetic Domains in Perovskite Nickelates Rourav Basak, Martin Bluschke, Ivan Zaluzhnyy, Nelson Hua, Boyan Stoychev, Anatoly Shabalin, Katrin Fuersich, Georg Christiani, Sujoy Roy, Eric Dufresne, Andi Barbour, Claudio Mazzoli, Oleg Shpyrko, Eva Benckiser, Bernhard Keimer, Alex Frano Rare earth nickelates are strongly correlated oxides who offer rich phenomenology due to interplay of structural, electronic and spin degrees of freedom. Here we study a thin film of PrNiO3 grown on a (LaAlO3)0.3(Sr2TaAlO6)0.7 (LSAT) substrate (tensile strain). This material exhibits concurrent structural (orthorhombic to monoclinic) electronic (metal to insulator) and magnetic (paramagnetic to antiferromagnetic) transitions. The phase transition is first order in nature and happens at ~115K with a hysteresis of 30K. Here we performed coherent resonant soft x-ray scattering tuned to the Ni L3 edge to study the emergence of the magnetic order parameter as the transition happens. Coherent magnetic x-ray scattering produces a speckle pattern that serves as a ‘fingerprint’ of a particular magnetic domain configuration. We observed a novel small-q periodic modulation of the magnetic Bragg peak intensity which only occurs at temperatures near the onset of transition. We argue coherent magnetic domain ordering as the origin of the small-q modulation when the transition is critically fluctuating. Furthermore we provide experimental evidence that this novel magnetic texture is decoupled from any structural origin. |
Friday, March 19, 2021 9:48AM - 10:00AM Live |
X43.00010: Structure and vibrations in rare-earth nickelates with nonempirical extended Hubbard functionals Luca Binci, Michele Kotiuga, Iurii Timrov, Nicola Marzari Transition-metal oxide represent one of the most interesting classes of materials in condensed matter physics. Notable representatives are the |
Friday, March 19, 2021 10:00AM - 10:12AM Live |
X43.00011: What drives the charge ordering in the rare-earth nickelates? Priya Mahadevan, Sagar Sarkar, Basudeb Mandal, Shishir Pandey, Cesare Franchini, Andrew Millis, Dipankar Das Sarma Usual examples of charge ordered systems are the doped transition metal oxides, where strong correlation effects at the transition metal site lead to the charge carriers being preferentially localized on some transition metal sites over others. The rare-earth (RE) nickelates of the form RENiO3 are unusual in that the undoped parent compounds are found to be charge ordered insulators for all rare earth atoms with the exception of La . Structural distortions accompany the charge ordering, with two Ni sites with different local environments of the oxygens emerging. Although these aspects have been identified for several decades now, the basic mechanism of what drives the charge ordering is still debated. |
Friday, March 19, 2021 10:12AM - 10:24AM Live |
X43.00012: Doping evolution of the electronic and magnetic structure in RENiO3 Jiarui Li, Robert Green, Zhen Zhang, Ronny Sutarto, Jerzy T. Sadowski, Zhihai Zhu, Grace H. Zhang, Da Zhou, Yifei Sun, Feizhou He, Shriram Ramanathan, Riccardo Comin Rare earth nickelates (RENiO3) exhibit metal-insulator transitions accompanied by the appearance of charge and spin order, at times concurrently. The understanding of the evolving ground state in these materials is hindered by the existence of multiple competing orders which are further coupled to various kinds of local perturbations (strain, defects, disorder). Recently, control of carrier doping by means of oxygen stoichiometry has been achieved in RENiO3, presenting an opportunity to study the broader electronic phase diagram of these systems. In this talk, I will present our recent soft X-ray absorption spectroscopy and imaging, resonant X-ray scattering, and extended multiplet ligand field theory modeling results on both pristine and electron doped RENiO3. We identified the redistribution of the doped carriers in the correlated electronic ground state. Moreover, the magnetic order is robust to substantial levels of carrier doping until it collapses at a doping threshold. Our results reveal the doping dependent evolution of the electronic structure and magnetic phase diagram in RENiO3. |
Friday, March 19, 2021 10:24AM - 10:36AM Live |
X43.00013: Oxygen vacancy induced site-selective Mott transition in LaNiO3 Xingyu Liao, Vijay Ramdin Singh, Hyowon Park Previous experiments show that LaNiO3-x, exhibits the metal-to-insulator transition as the oxygen vacancy level increases. |
Friday, March 19, 2021 10:36AM - 10:48AM Live |
X43.00014: Experiments and Model for the T → 0 Metal-Insulator Behavior of RNiO3: Evidence for a Bond-Percolation Transition. Gregorio Ponti, Quinn Timmers, Sara J Irvine, Alexander Barajas, Holland Frieling, Lucas P. Moynihan, Jonathan D. K. Tebo, John T. Markert Metal-insulator (M-I) and magnetic Tc's in RNiO3 vary with rare-earth-ion R size; only LaNiO3 (largest R) remains metallic. For smaller R3+, as T is lowered, thermal straightening of bond angles diminishes. We model the T→0 M-I transition with bond percolation on the nearly simple-cubic lattice, assuming only that each small R ion breaks all 12 surrounding bonds; we predict a universal T→0 M-I transition for all La1-xRxNiO3 alloys. To augment evidence from the known alloy with R = Y (M-I transition at xc ≈ 0.25–0.30[1]), we are synthesizing La1-xNdxNiO3. The tolerance factor t for this alloy at x = 0.5 places it within the metallic region (t ≈ 0.943), while bond percolation predicts an insulator (x > 0.29). We are investigating bulk syntheses in high oxygen pressure, high static pressure, and precursor routes, as well as epitaxial film growth using pulsed laser deposition. The model provides an exact mapping of the small-R fraction x to the bond fraction p, so that experiments can quantify critical behavior near the percolation threshold pc; in particular, we find xc = 0.2937343(7) for the known pc = 0.2488126(5). |
Friday, March 19, 2021 10:48AM - 11:00AM Live |
X43.00015: Electronic structure of higher-order Ruddlesden Popper nickelates Rn+1NinO3n+1 (R = rare-earth, n = 4, 5, 6) Antia Botana, Betul Pamuk, Jyoti Krishna, Jesse Kapeghian, Harrison LaBollita, Dibyendu Dey, Chase Hanson Layered nickelates have long been considered close analogs to cuprates and have been intensively investigated for their potential for superconductivity. The realization of this promise came last year, as NdNiO2 was indeed shown to be superconducting upon hole doping. This material is obtained via topotactic reduction from its parent perovskite NdNiO3 phase and is simply the infinite layer member of a larger structural series. In this context, analyzing the electronic properties of the yet unexplored parent Ruddlesden-Popper nickelate phases Rn+1NinO3n+1 (n=4-6) becomes important. Our systematic first-principles calculations in these materials reveal similarities and differences with cuprates in terms of their electronic structure. For example, large hole dx2-y2 Fermi surfaces that closely resemble the fermiology of optimally hole-doped cuprates are found, but they are accompanied by non-cuprate-like extra bands of primarily dz2 character. |
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