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Bruno, E.; Ginatempo, B.; Giuliano, E. S.

doi:10.1103/physrevb.52.14557

Cited by 15 publications

(8 citation statements)

References 26 publications

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“…This value is not far from that reported in Ref. 36 for AgPd, while at the equiatomic concentration, the neck is already open in CuPt. Subtle details in the relative importance of the spin-orbit interaction in these isoelectronic systems are able to move up and down the relevant d and sp bands of the transition-metal alloy with respect to the Fermi energy thus changing the order in which the relevant ETT occur.…”

Section: B the Fermi Surfaces Of Fcc And Bcc Cu-pd Disordered Alloyssupporting

confidence: 60%

“…35 All the calculations have been fully relativistic, since, as discussed in Ref. 36, the spin-orbit interaction removes certain degeneracies that are present in a nonrelativistic theory and could have qualitative effects on the relevant FS topologies. The multiple-scattering series have been truncated in the angular momentum space at lϭ3.…”

Section: A Total-energy Calculation For Fcc and Bcc Cu-pd Disorderedmentioning

confidence: 99%

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Fermi surface incommensurate nestings and phase equilibria in Cu-Pd alloys

2001

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The Cu-Pd phase diagram shows two low-temperature ordered phases corresponding to B2 and L1 2 superlattices or, regardless of the site occupation, to bcc and fcc geometrical arrangements. We show how the phase equilibria between these intermetallic compounds can be understood by introducing a hypothetical bcc random-alloy phase and a three-step transformation from B2 to random bcc to random fcc to L1 2 . The two order-disorder transformations, B2 to random bcc and random fcc to L1 2 , analyzed in the framework of the concentration wave-functional theory, appear to be ruled by the sizes of the relevant Fermi surface ͑FS͒ nesting vectors in the two random-alloy systems. The transformation between the bcc and fcc solid solution phase is studied by first-principles Korringa-Kohn-Rostoker and coherent-potential approximation calculations, and it is shown to be influenced by electronic topological transitions occurring in the same systems. Our analysis points out the preeminent role played by the lattice-incommensurate FS nesting vectors that in both the random-alloy systems, give rise to frustrated concentration waves. The location of the B2-L1 2 coexistence at Tϭ0 appears to be determined by the condition that the concentration waves of the fcc and bcc random alloys are equally frustrated.

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Section: B the Fermi Surfaces Of Fcc And Bcc Cu-pd Disordered Alloyssupporting

confidence: 60%

Section: A Total-energy Calculation For Fcc and Bcc Cu-pd Disorderedmentioning

confidence: 99%

Fermi surface incommensurate nestings and phase equilibria in Cu-Pd alloys

2001

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“…6, one also notes that the Fermi surfaces of Au-Pd alloys bear close resemblance to those of Cu-Pd and Ag-Pd alloys. 61,62 To demonstrate the connection between the geometry of the Fermi surface and the type of interactions (and consequently the ordering in the Au-Pd alloys), Fig. 7 shows the Fourier transform of the EPI parameters calculated between the X and W positions of the fcc Brillouin zone.…”

Section: E Fermi Surface and Ordered Structuresmentioning

confidence: 99%

Atomic ordering in Au-(42 to 50) at.%Pd: A diffuse scattering and first-principles investigation

2012

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Atomic ordering in Au-Pd alloys was studied by diffuse x-ray scattering and first-principles methods. Diffuse scattering was done of a single crystal of Au-48 at.% Pd that was aged at 703 K for 24 days. The weakly modulated short-range-order scattering exhibits diffuse maxima with an incommensurate wave vector, which can be related to a Fermi-surface nesting mechanism. From effective pair interaction parameters determined by the inverse Monte Carlo method, a one-dimensional long-period superstructure of the CH structure, LPS1, was found for AuPd. Concurrent electronic-structure calculations of the effective cluster interaction (ECI) parameters indicated the presence of another closely related superstructure, LPS2, at 0 K. At the same time, direct first-principles calculations of the total energies of the CH structure and further one-dimensional long-period superstructures predicted the stabilization of LPS4. Although the energy differences between these structures are small and a complex behavior of the effective interactions is expected due to the Fermi-surface nesting, experimental data and theoretical results both support the stabilization of a long-period superstructure of the CH structure for AuPd at 0 K. The ECI parameters determined by the screened generalized perturbation method also predicted a groundstate structure different from Au 7 Pd 5 , previously obtained from cluster expansion calculations. Its energetic preference was confirmed by direct total-energy calculations.

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“…We follow Delczeg-Czirjak et al 5 in focusing our attention on the changes in the Fermi surface topology, as obtained from Bloch spectral function calculations. 3,4 As originally showed by Bruno et al, a continuous change in concentration can lead to a series of discrete transitions: for certain ratios of the Ag, Pd constituents, the connectivity of the Fermi surface may change radically, as In order to facilitate the understanding of this connection, we depict elastic anomalies plots of the bulk modulus B 0 (c) underneath a color-coded representation of the Bloch spectral function for the alloy A B (k, ) = − 1 π G(k, ), evaluated at the Fermi energy = E F for each concentration c (see Figs. 4, 7, and 8).…”

Section: Single-site Theorymentioning

confidence: 99%

“…Bruno et al [2][3][4] have previously examined such system from the point of view of variations in the Fermi surface as a function of the constituents' ratio, in a fixed face centred cubic (fcc) reference geometry. Substitution of Pd with Ag changes the topology of the Fermi surface drastically, and so-called Lifshitz or electronic topological transitions (ETT) occur.…”

Section: Introductionmentioning

confidence: 99%

Elastic anomalies and long/short-range ordering effects: A first-principles investigation of the AgcPd1−csolid solution

et al. 2012

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We investigate the elastic properties of the binary alloy Ag-Pd. The lattice constant of this system shows significant deviations from the linear behavior anticipated by the semi-empirical Vegard's rule. This effect was formerly studied by assuming total substitutional disorder, and described by the coherent potential approximation (CPA). Theoretical phase diagram investigations have however suggested three ordered phases at low temperatures, and we extend our first-principles investigation to include such scenarios through the adoption of an extended unit cell representation and a recently developed multisublattice generalization of the original CPA. This allows us to explore equilibrium lattice constant and bulk modulus within a unified approach even in the presence of partial long-range order. We obtain significant variations of the bulk modulus in comparison to the totally disordered picture, and again very rich deviations from more intuitive predictions of a simple linear behavior. We follow former suggestions to analyze the different regimes in connection with topological transitions of the Fermi surface, examined through Bloch spectral function calculations.

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Fermi surfaces and electronic topological transitions in metallic random alloys. II.AgcPd1

Cited by 15 publications

References 26 publications

Fermi surface incommensurate nestings and phase equilibria in Cu-Pd alloys

Fermi surface incommensurate nestings and phase equilibria in Cu-Pd alloys

Atomic ordering in Au-(42 to 50) at.%Pd: A diffuse scattering and first-principles investigation

Elastic anomalies and long/short-range ordering effects: A first-principles investigation of the AgcPd1−csolid solution

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