Nearly free electrons in a 5
            <i>d</i>
            delafossite oxide metal

Kushwaha, Pallavi; Sunko, Veronika; Moll, Philip J. W.; Bawden, L.; Riley, J. M.; Nandi, Nabhanila; Rösner, H.; Schmidt, Marcus; Arnold, Frank; Hassinger, Elena; Kim, T. K.; Hoesch, Moritz; Mackenzie, A. P.; King, P. D. C.

doi:10.1126/sciadv.1500692

Cited by 66 publications

(96 citation statements)

References 45 publications

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“…A further class of materials recently discovered to have extremely long mean free paths at low temperature are the delafossite oxide metals PdCoO 2 , PtCoO 2 and PdCrO 2 [10,11]. Each can have resistive mean free paths of microns at low temperatures [12][13][14]. Indeed, in the most conductive single crystals of PdCoO 2 , with resistivities as low as 8 nΩcm, mean free paths as long as 20 µm have been reported [15].…”

Section: Introductionmentioning

confidence: 99%

Controlled Introduction of Defects to Delafossite Metals by Electron Irradiation

et al. 2020

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The delafossite metals PdCoO2, PtCoO2 and PdCrO2 are among the highest conductivity materials known, with low temperature mean free paths of tens of microns in the best as-grown single crystals. A key question is whether these very low resistive scattering rates result from strongly suppressed backscattering due to special features of the electronic structure, or are a consequence of highly unusual levels of crystalline perfection. We report the results of experiments in which high energy electron irradiation was used to introduce point disorder to the Pd and Pt layers in which the conduction occurs. We obtain the cross-section for formation of Frenkel pairs in absolute units, and cross-check our analysis with first principles calculations of the relevant atomic displacement energies. We observe an increase of resistivity that is linear in defect density with a slope consistent with scattering in the unitary limit. Our results enable us to deduce that the as-grown crystals contain extremely low levels of in-plane defects of approximately 0.001%. This confirms that crystalline perfection is the most important factor in realizing the long mean free paths, and highlights how unusual these delafossite metals are in comparison with the vast majority of other multi-component oxides and alloys. We discuss the implications of our findings for future materials research.

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Section: Introductionmentioning

confidence: 99%

Controlled Introduction of Defects to Delafossite Metals by Electron Irradiation

et al. 2020

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“…Furthermore, depending on the chemical composition, a plethora of behaviors can be evidenced. For instance, for A in a d 9 configuration, e.g., A = Pd or Pt, highly metallic compounds with anomalous temperature dependence of the resistivity have been reported [4][5][6][7]. The transport in these compounds has been found to be strongly anisotropic, with a degree of anisotropy that may reach 1000 [4,5,8].…”

Section: Introductionmentioning

confidence: 99%

Magnetoelectric properties of multiferroic CuCrO2 studied by means of ab initio calculations and Monte Carlo simulations

et al. 2017

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Motivated by the discovery of multiferroicity in the geometrically frustrated triangular antiferromagnet CuCrO2 below its Néel temperature TN , we investigate its magnetic and ferroelectric properties using ab initio calculations and Monte Carlo simulations. Exchange interactions up to the third nearest neighbors in the ab plane, inter-layer interaction and single ion anisotropy constants in CuCrO2 are estimated by series of density functional theory calculations. In particular, our results evidence a hard axis along the [110] direction due to the lattice distortion that takes place along this direction below TN . Our Monte Carlo simulations indicate that the system possesses a Néel temperature TN ≈ 27 K very close to the ones reported experimentally (TN = 24 − 26 K). Also we show that the ground state is a proper-screw magnetic configuration with an incommensurate propagation vector pointing along the [110] direction. Moreover, our work reports the emergence of spin helicity below TN which leads to ferroelectricity in the extended inverse Dzyaloshinskii-Moriya model. We confirm the electric control of spin helicity by simulating P -E hysteresis loops at various temperatures.

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“…Several important technological applications have been proposed for members of this family, such as electrodes for hydrogen production by photo-electrochemical water splitting67, as luminescent materials8, in solar cells91011, for thermoelectricity12131415, as possible transparent supercondutors16, etc. Recently, it was also found that delafossite PtCoO 2 behaves like a nearly free-electron system, turning this surprising 5d transition-metal system in the most conductive oxide known17.…”

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confidence: 99%

High-throughput search of ternary chalcogenides for p-type transparent electrodes

Shi

Cerqueira

Cui

et al. 2017

Sci Rep

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Delafossite crystals are fascinating ternary oxides that have demonstrated transparent conductivity and ambipolar doping. Here we use a high-throughput approach based on density functional theory to find delafossite and related layered phases of composition ABX2, where A and B are elements of the periodic table, and X is a chalcogen (O, S, Se, and Te). From the 15 624 compounds studied in the trigonal delafossite prototype structure, 285 are within 50 meV/atom from the convex hull of stability. These compounds are further investigated using global structural prediction methods to obtain their lowest-energy crystal structure. We find 79 systems not present in the materials project database that are thermodynamically stable and crystallize in the delafossite or in closely related structures. These novel phases are then characterized by calculating their band gaps and hole effective masses. This characterization unveils a large diversity of properties, ranging from normal metals, magnetic metals, and some candidate compounds for p-type transparent electrodes.

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Nearly free electrons in a 5 d delafossite oxide metal

Abstract: Transport and ARPES reveal extremely good metallicity arising from almost free-electron behavior in single-crystal PtCoO2.

Cited by 66 publications

References 45 publications

Controlled Introduction of Defects to Delafossite Metals by Electron Irradiation

Controlled Introduction of Defects to Delafossite Metals by Electron Irradiation

Magnetoelectric properties of multiferroic CuCrO2 studied by means of ab initio calculations and Monte Carlo simulations

High-throughput search of ternary chalcogenides for p-type transparent electrodes

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