Persistence of antiferromagnetic order upon La substitution in the 
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 Mott insulator 
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Pincini, D.; Boseggia, S.; Perry, Robin; Gutmann, Matthias J.; Riccó, Sara; Veiga, L. S. I.; Dashwood, C. D.; Collins, S.P.; Nisbet, Gareth; Bombardi, A.; Porter, D. G.; Baumberger, F.; Boothroyd, A. T.; McMorrow, D. F.

doi:10.1103/physrevb.98.014429

Cited by 12 publications

(37 citation statements)

References 56 publications

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“…The structural properties were also investigated by means of single crystal neutron diffraction (see Ref. 16 for further details). The parent compound (x = 0) MIT is followed upon cooling below T N ≈ 110 K by a phase transition to a basal plane canted AFM state [2][3][4]16,17,31,32,34 .…”

Section: A Samples and Methodsmentioning

confidence: 99%

“…16 for further details). The parent compound (x = 0) MIT is followed upon cooling below T N ≈ 110 K by a phase transition to a basal plane canted AFM state [2][3][4]16,17,31,32,34 . La substitution causes the MIT and Néel temperatures to decrease and be completely suppressed at a doping concentration slightly greater than x = 0.10 16,17 .…”

Section: A Samples and Methodsmentioning

confidence: 99%

“…For the hopping amplitudes, we considered a representative set of electronic parameters for the Ru-O-Ru cluster that is consistent with typical amplitudes obtained from first-principle calculations on ruthenium oxides 7,15,38,[47][48][49] . Given the limited impact of La substitution on the Ru-O-Ru bond angle and octahedral tilt away from the c axis 16 , we assumed that the hopping amplitudes are not quantitatively affected by the La concentration.…”

Section: Theoretical Calculationsmentioning

confidence: 99%

“…Ca 2 RuO 4 has attracted considerable attention in recent years as the Mott-insulating analogue of the unconventional superconductor Sr 2 RuO 4 [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] . A welldocumented metal to insulator transition (MIT) occurs at T MIT = 357 K, concomitant with a first-order structural transition from a high-temperature quasitetragonal phase to a low-temperature orthorhombic one (P bca space group) 1,2,4,17 .…”

Section: Introductionmentioning

confidence: 99%

“…This is expected to significantly change the local physics of the Ru 4+ ion and thus have a sizeable impact on the parent compound electronic structure. However, experimental studies on La-doped Ca 2 RuO 4 reported to date 16,17,31,32 have not addressed in detail the impact of the structural changes on the low-energy electronic structure.…”

Section: Introductionmentioning

confidence: 99%

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Tuning of the Ru4+ ground-state orbital population in the 4d4 Mott insulator C

et al. 2019

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The ground-state orbital occupancy of the Ru 4+ ion in Ca2−xLaxRuO4 [x = 0, 0.05(1), 0.07(1) and 0.12(1)] was investigated by performing X-ray absorption spectroscopy (XAS) in the vicinity of the O K edge as a function of angle between the incident beam and the surface of the single-crystal samples. A minimal model of the hybridization between the O 2p states probed at the K edge and the Ru 4d orbitals was used to analyze the XAS data, allowing the ratio of hole occupancies nxy/nyz,zx to be determined as a function of doping and temperature. For the samples displaying a low-temperature insulating ground-state (x ≤ 0.07), nxy/nyz,zx is found to increase significantly with increasing doping, with increasing temperature acting to further enhance nxy/nyz,zx. For the x = 0.12 sample, which has a metallic ground-state, the XAS spectra are found to be independent of temperature, and not to be describable by the minimal hybridization model, while being qualitatively similar to the spectra displayed by the x ≤ 0.07 samples above their insulating to metallic transitions. To understand the origin of the evolution of the electronic structure of Ca2−xLaxRuO4 across its phase diagram, we have performed theoretical calculations based on a model Hamiltonian, comprising electron-electron correlations, crystal field (∆) and spin-orbit coupling (λ), of a Ru-O-Ru cluster, with realistic values used to parameterize the various interactions taken from the literature. Our calculations of the Ru hole occupancy as a function of ∆/λ provide an excellent description of the general trends displayed by the data. In particular they establish that the enhancement of nxy/nyz,zx is driven by significant modifications to the crystal field as the tetragonal distortion of the RuO6 octahedral changes from compressive to tensile with La doping. We have also used our model to show that the hole occupancy of the O 2p and Ru 4d orbitals display the same general trend as a function of ∆/λ, thus validating the minimal hybridization model used to analyze the data. In essence, our results suggest that the predominant mechanism driving the emergence of the low-temperature metallic phase in La doped Ca2RuO4 is the structurally induced redistribution of holes within the t2g orbitals, rather that the injection of free carriers.

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Section: A Samples and Methodsmentioning

confidence: 99%

Section: A Samples and Methodsmentioning

confidence: 99%

Section: Theoretical Calculationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Tuning of the Ru4+ ground-state orbital population in the 4d4 Mott insulator C

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Guiding antiferromagnetic transitions in Ca$$_{2}$$RuO$$_{4}$$

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et al. 2022

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Understanding and controlling the transition between antiferromagnetic states having different symmetry content with respect to time-inversion and space-group operations are fundamental challenges for the design of magnetic phases with topologically nontrivial character. Here, we consider a paradigmatic antiferromagnetic oxide insulator, Ca$$_{2}$$ 2 RuO$$_{4}$$ 4 , with symmetrically distinct magnetic ground states and unveil a novel path to guide the transition between them. The magnetic changeover results from structural and orbital reconstruction at the transition metal site that in turn arise as a consequence of substitutional doping. By means of resonant X-ray diffraction we track the evolution of the structural, magnetic, and orbital degrees of freedom for Mn doped Ca$$_{2}$$ 2 RuO$$_{4}$$ 4 to demonstrate the mechanisms which drive the antiferromagnetic transition. While our analysis focuses on a specific case of substitution, we show that any perturbation that can impact in a similar way on the crystal structure, by reconstructing the induced spin–orbital exchange, is able to drive the antiferromagnetic reorganization.

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Observation of spin-orbit excitations and Hund's multiplets in Ca2RuO4

et al. 2019

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We use Ru L3-edge (2838.5 eV) resonant inelastic x-ray scattering (RIXS) to quantify the electronic structure of Ca2RuO4, a layered 4d-electron compound that exhibits a correlation-driven metal-insulator transition and unconventional antiferromagnetism. We observe a series of Ru intraionic transitions whose energies and intensities are well described by model calculations. In particular, we find a J = 0 → 2 spin-orbit excitation at 320 meV, as well as Hund's-rule driven S = 1 → 0 spin-state transitions at 750 and 1000 meV. The energy of these three features uniquely determines the spin-orbit coupling, tetragonal crystal-field energy, and Hund's rule interaction. The parameters inferred from the RIXS spectra are in excellent agreement with the picture of excitonic magnetism that has been devised to explain the collective modes of the antiferromagnetic state. L3-edge RIXS of Ru compounds and other 4d-electron materials thus enables direct measurements of interactions parameters that are essential for realistic model calculations.

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Persistence of antiferromagnetic order upon La substitution in the 4d4 Mott insulator Ca2RuO4

Cited by 12 publications

References 56 publications

Tuning of the Ru4+ ground-state orbital population in the 4d4 Mott insulator C

Tuning of the Ru4+ ground-state orbital population in the 4d4 Mott insulator C

Guiding antiferromagnetic transitions in Ca$$_{2}$$RuO$$_{4}$$

Observation of spin-orbit excitations and Hund's multiplets in Ca2RuO4

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