Electronic Structure and Magnetism of the Triple-layered Ruthenate Sr${4}$Ru${3}$O$_{10}$ (original) (raw)
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Layer dependent antiferromagnetism in the Sr4Ru3O10 ruthenate at the metamagnetic-like transition
Journal of Magnetism and Magnetic Materials
We have investigated the metamagnetic-like transition in the triple layer ruthenate Sr4Ru3O10 by means of neutron diffraction from single crystals. The magnetic structure of the compound appears to be determined in a complex way by the two substructures of inequivalent ruthenium ions. At Tc=105K the system has a sharp transition into a ferromagnetic state along the c-axis which is driven by the ruthenium atoms in the central octahedra of the triple layers whereas the substructure of the outer ruthenium atoms tend to align in the ab plane achieving an antiferromagnetic order at the metamagnetic transition T*~50K. Below T* the strong anisotropy along c prevails, the outer ruthenium tend to align along the c-axis and the in-plane antiferromagnetic order disappears. This finding confirms the delicate balance between antiferro and ferromagnetic couplings in the (Sr,Ca)n+1RunO3n+1 family of compounds, and proves the layer dependence of the magnetic anisotropy in Sr4Ru3O10.
Antiferromagnetism at T > 500 K in the Layered Hexagonal Ruthenate SrRu2O6
Physical Review B
We report an experimental and computational study of the magnetic and electronic properties of the layered Ru(V) oxide SrRu 2 O 6 (hexagonal, P31m), which shows antiferromagnetic order with a Néel temperature of 563(2) K, among the highest for 4d oxides. Magnetic order occurs both within edge-shared octahedral sheets and between layers and is accompanied by anisotropic thermal expansivity that implies strong magnetoelastic coupling of Ru(V) centers. Electrical transport measurements using focused-ion-beam-induced deposited contacts on a micron-scale crystallite as a function of temperature show p-type semiconductivity. The calculated electronic structure using hybrid density functional theory successfully accounts for the experimentally observed magnetic and electronic structure, and Monte Carlo simulations reveal how strong intralayer as well as weaker interlayer interactions are a defining feature of the high-temperature magnetic order in the material.
Magnetic transition and magnetic structure of Sr4Ru3O10
arXiv (Cornell University), 2006
We have investigated the magnetic transition and magnetic structure of triple-layered ruthenate Sr4Ru3O10 directly using neutron scattering techniques. Only one ferromagnetic phase is observed, and previously proposed antiferromagnetic phase transitions are ruled out. The complex anisotropic magnetotransport, magnetization and in-plane metamagnetic behaviors of this quasi two-dimensional (2D) material are most likely due to magnetic domain processes with strong magnetocrystalline anisotropy and a strongly anisotropic demagnetization factor.
Physical Review B, 1997
We have measured photoemission and oxygen 1s x-ray absorption spectra of the ferromagnetic metal SrRuO 3 and compared them with a first-principles band-structure calculation. The overall distribution of Ru 4d and O 2p spectral weight is in good agreement with that predicted by the band-structure calculation. However, the observed spectral line shape of the Ru 4d band is spread over a wide energy range and the emission intensity at the Fermi level is weakened compared to the band-structure calculation. This implies the importance of electron correlation in the Ru oxide. ͓S0163-1829͑97͒05736-6͔
Signature of Electron-Phonon Correlation in the Band Structure of Sr 4 Ru 3 O 10
We report the first angle resolved photoemission spectroscopy measurements on the three-layered strontium ruthenate Sr4Ru3O10. These data reveal the presence of kinks in the near-Fermi-level band dispersion, with energies ranging from 30 meV to 69 meV. The kink energies have a good correspondence with the energy of the phononic modes previously reported by Raman spectroscopy measurements and lattice dynamic calculations. We interpret this as the fingerprint of strong electron-phonon coupling present in this system.
Physical Review B, 2008
We report an unusual nearly ferromagnetic, heavy-mass state with a surprisingly large Wilson ratio Rw (e.g., Rw ~ 700 for x = 0.2) in double layered ruthenates (Sr 1−x Ca x ) 3 Ru 2 O 7 with 0.08 <x< 0.4. This state does not evolve into a long-range ferromagnetically ordered state despite considerably strong ferromagnetic correlations, but freezes into a cluster-spin-glass at low temperatures. In addition, evidence of non-Fermi liquid behavior is observed as the spin freezing temperature of the cluster-spin-glass approaches zero near x ≈ 0.1. We discuss the origin of this unique magneticstate from the Fermi surface information probed by Hall effect measurements.
Physical Review B, 2018
By using the local-density approximation + dynamical mean-field theory approach, we study the low-energy electronic properties and the optical conductivity of the layered ruthenates Sr 2 RuO 4 and Sr 3 Ru 2 O 7. We study the interplay of spin-orbit, crystal-field, and Coulomb interactions, including the tetragonal terms of the Coulomb tensor. We show that the spin-orbit interaction is multifaced; depending on the parameter regime, filling, and temperature, it can either enhance or reduce the effective strength of correlations. We compare the results based on the two common approximations for the screened Coulomb parameters, the constrained random-phase approximation (cRPA) and the constrained local-density approximation. We show that the experimental Drude peak is better reproduced by the cRPA parameters, hinting to relatively small mass renormalizations. We find that including the spin-orbit interaction is, however, important, for a realistic description. We show that Coulomb terms with tetragonal D 4h symmetry have a strong effect on the mass-enhancement anisotropy, but they do not affect sizably the total spectral function or the in-plane conductivity.
Toward intrinsic functionalities of bilayered ruthenate Sr3Ru2O7
Physical Review B, 2009
Polymorphic materials are known for being prone to intergrowth. Remarkable examples are strontium ruthenates whose properties are dramatically tuned by impurities and disorder. In particular, Sr 3 Ru 2 O 7 shows a strong variation in transport and magnetic properties depending on synthesis process. It is therefore crucial to correlate atomic structure and properties to identify the functionalities of individual nanostructural constituents. We report a comparative study between Sr 3 Ru 2 O 7 crystals grown as single phase and in Sr 3 Ru 2 O 7 -Sr 2 RuO 4 eutectics. Our analysis by transmission electron microscopy reveals that Sr 3 Ru 2 O 7 domains of the eutectic have a significantly lower level of impurities compared to Sr 3 Ru 2 O 7 single-phase crystals, where intergrowths of Sr 4 Ru 3 O 10 and SrRuO 3 phase are seen. This is confirmed by magnetic measurements. These results identify the eutectic solidification as a fruitful way to grow highly pure crystals of polymorphic materials which, in combination with recent technological developments allowing the extraction of embedded features of crystals, opens a pathway for understanding of their physical properties and applications.
Spin-Orbit Coupling and Electronic Correlations in Sr2RuO4
Physical Review Letters, 2018
We investigate the interplay of spin-orbit coupling (SOC) and electronic correlations in Sr2RuO4 using dynamical mean-field theory. We find that SOC does not affect the correlation-induced renormalizations, which validates the Hund's metal picture of ruthenates even in the presence of the sizeable SOC relevant to these materials. Nonetheless, SOC is found to change significantly the electronic structure at k-points where a degeneracy applies in its absence. We explain why these two observations are consistent with one another and calculate the effects of SOC on the correlated electronic structure. The magnitude of these effects is found to depend on the energy of the quasiparticle state under consideration, leading us to introduce the notion of an energy-dependent quasiparticle spin-orbit coupling λ * (ω). This notion is generally applicable to all materials in which both the spin-orbit coupling and electronic correlations are sizeable.
Temperature-dependent bilayer ferromagnetism in Sr3Ru2O7
Physical Review B, 2006
The Ruthenium based perovskites exhibit a wide variety of interesting collective phenomena related to magnetism originating from the Ru 4d electrons. Much remains unknown concerning the nature of magnetic fluctuations and excitations in these systems.