The properties of ultrapure delafossite metals

Abstract

Although they were first synthesized in chemistry laboratories nearly fifty years ago, the physical properties of the metals PdCoO2, PtCoO2 and PdCrO2 have only more recently been studied in detail. The delafossite structure contains triangular co-ordinated atomic layers, and electrical transport in the delafossite metals is strongly two-dimensional. Their most notable feature is their in-plane conductivity, which is amazingly high for oxide metals. At room temperature, the conductivity of non-magnetic PdCoO2 and PtCoO2 is higher per carrier than those of any alkali metal and even the most conductive elements, copper and silver. At low temperatures the best crystals have resistivities of a few nΩcm, corresponding to mean free paths of tens of microns. PdCrO2 is a frustrated antiferromagnetic metal, with magnetic scattering contributing to the resistivity at high temperatures and small gaps opening in the Fermi surface below the Néel temperature. There is good evidence that electronic correlations are weak in the Pd/Pt layers but strong in the Co/Cr layers; indeed the Cr layer in PdCrO2 is thought to be a Mott insulator. The delafossite metals therefore act like natural heterostructures between strongly correlated and nearly free electron sub-systems. Combined with the extremely high conductivity, they provide many opportunities to study electrical transport and other physical properties in new regimes. The purpose of this review is to describe current knowledge of these fascinating materials and set the scene for what is likely to be a considerable amount of future research.

References in corpus (22)

• Evidence for hydrodynamic electron flow in PdCoO${}_2$
• Hydrodynamic electron flow in high-mobility wires
• Ballistic transport exceeding 28 μm in CVD grown graphene
• Axial anomaly and longitudinal magnetoresistance of a generic three dimensional metal
• On the search for the chiral anomaly in Weyl semimetals: The negative longitudinal magnetoresistance
• Quantum oscillations and high carrier mobility in the delafossite PdCoO${}_2$
• Extremely Large Magnetoresistance in the Nonmagnetic Metal PdCoO2
• Unconventional Anomalous Hall Effect in the Metallic Triangular-Lattice Magnet PdCrO2
• Critical behavior of the metallic triangular-lattice Heisenberg antiferromagnet PdCrO2
• On the metallic conductivity of the delafossites PdCoO2 and PtCoO2
• Quantum Oscillations of the Metallic Triangular-lattice Antiferromagnet PdCrO2
• Inter-planar coupling dependent magnetoresistivity in high purity layered metals
• Magnetic structure of the conductive triangular-lattice antiferromagnet PdCrO2
• Electronic Structure of the Metallic Antiferromagnet PdCrO${}_2$ Measured by Angle-Resolved Photoemission Spectroscopy
• Exceptional type-I superconductivity of the layered silver oxide Ag${}_5$Pb${}_2$O${}_6$
• Large anisotropic thermal conductivity of intrinsically two-dimensional metallic oxide PdCoO${}_2$
• Anomalous Magnetothermopower in a Metallic Frustrated Antiferromagnet
• Impact of strain-induced electronic topological transition on the thermoelectric properties of PtCoO${}_2$ and PdCoO${}_2$
• Cascade of field-induced magnetic transitions in a frustrated antiferromagnetic metal
• Three dimensional magnetism and coupling to conduction electrons in PdCrO2
• Interplay between localized and itinerant d electrons in a frustrated metallic antiferromagnet, 2H-AgNiO2
• Crystal growth, resistivity and Hall effect of the delafossite metal PtCoO${}_2$

Cited by in corpus (75)

• Electronic structure of quantum materials studied by angle-resolved photoemission spectroscopy
• Rational Strain Engineering in Delafossite Oxides for Highly Efficient Hydrogen Evolution Catalysis in Acidic Media
• Hydrodynamic Electron Flow and Hall Viscosity
• Maximal Rashba-like spin splitting via kinetic energy-driven inversion symmetry breaking
• Unconventional aspects of electronic transport in delafossite oxides
• Highly conductive PdCoO2 ultrathin films for transparent electrodes
• Itinerant ferromagnetism of the Pd-terminated polar surface of PdCoO${}_2$
• Yb delafossites: unique exchange frustration of 4f spin 1/2 moments on a perfect triangular lattice
• Directional ballistic transport in the two-dimensional metal PdCoO2
• Growth of metallic delafossite PdCoO2 by molecular beam epitaxy
• Electron hydrodynamics with a polygonal Fermi surface
• Thermal resistivity and hydrodynamics of the degenerate electron fluid in antimony
• Super-geometric electron focusing on the hexagonal Fermi surface of PdCoO${}_2$
• $h/e$ Oscillations in Interlayer Transport of Delafossites
• Pulsating flow and boundary layers in viscous electronic hydrodynamics
• Evidence of a coupled electron-phonon liquid in NbGe${}_2$
• Hidden kagome-lattice picture and origin of high conductivity in delafossite PtCoO${}_2$
• Boundary condition and geometry engineering in electronic hydrodynamics
• Field-induced compensation of magnetic exchange as the possible origin of reentrant superconductivity in UTe${}_2$
• Anomalous Hall effect at the spontaneously electron-doped polar surface of PdCoO2 ultrathin films
• From basic properties to the Mott design of correlated delafossites
• The planar triangular $S=3/2$ magnet AgCrSe${}_2$: magnetic frustration, short range correlations, and field tuned anisotropic cycloidal magnetic order
• Non-local hydrodynamic transport and collective excitations in Dirac fluids
• Tuneable electron-magnon coupling of ferromagnetic surface states in PdCoO${}_2$
• Quasiparticle interference and quantum confinement in a correlated Rashba spin-split 2D electron liquid
• Magnetic interactions in PdCrO${}_2$ and their effects on its magnetic structure
• Growth of CuFeO${}_2$ Single Crystals by the Optical Floating-Zone Technique
• Nonreciprocal transport in a Rashba ferromagnet, delafossite PdCoO${}_2$
• Optical signatures of shear collective modes in strongly interacting Fermi liquids
• Low-symmetry non-local transport in microstructured squares of delafossite metals
• Electrons in helical magnetic field: a new class of topological metals
• Layered palladates and their relation to nickelates and cuprates
• Hidden Mott insulator in metallic PdCrO${}_2$
• Perfect separation of intraband and interband excitations in PdCoO${}_2$
• Metallic delafossite thin films for unique device applications
• Determination of the phase coherence length of PdCoO${}_2$ nanostructures
• Para-hydrodynamics from weak surface scattering in ultraclean thin flakes
• Stripe magnetic order and field-induced quantum criticality in the perfect triangular-lattice antiferromagnet CsCeSe${}_2$
• Energy drag in particle-hole symmetric systems as a quantum quench
• Molecular beam epitaxy growth of the highly conductive oxide SrMoO${}_3$
• Quasi two-dimensional Fermi surface topography of the delafossite PdRhO${}_2$
• The Fermi surface of PtCoO2 from quantum oscillations and electronic structure calculations
• Unraveling the unusually high electrical conductivity of the delafossite metal PdCoO${}_2$
• Avoided metallicity in a hole-doped Mott insulator on a triangular lattice
• Magnetic frustration and spontaneous rotational symmetry breaking in PdCrO2
• Investigation of Planckian behavior in a high-conductivity oxide: PdCrO${}_2$
• Controlled introduction of defects to delafossite metals by electron irradiation
• Emergent magnetism with continuous control in the ultrahigh conductivity layered oxide PdCoO2
• Effective reduction of PdCoO2 thin films via hydrogenation and sign tunable anomalous Hall effect
• Bloch-Lorentz magnetoresistance oscillations in delafossites
• Fully two-dimensional incommensurate charge modulation on the Pd-terminated polar surface of PdCoO2
• Probing hidden Mott gap and incommensurate charge modulation on the polar surfaces of PdCrO${}_2$
• Probing spin correlations using angle resolved photoemission in a coupled metallic/Mott insulator system
• Theoretical design of highly correlated electron states in delafossite heterostructures
• Universal superdiffusive modes in charged two dimensional liquids
• Heisenberg spins on an anisotropic triangular lattice: PdCrO2 under uniaxial stress
• Intermediate-scale theory for electrons coupled to frustrated local-moments
• Adsorbate-induced formation of a surface-polarity-driven nonperiodic superstructure
• $T-$linear resistivity from magneto-elastic scattering: application to PdCrO${}_2$
• Application of SQUIDs to low temperature and high magnetic field measurements - Ultra low noise torque magnetometry
• Anomalous Hall effect in electrolytically reduced PdCoO${}_2$ thin films
• Diffusion-assisted molecular beam epitaxy of CuCrO${}_2$ thin films
• Dichotomy of electron-phonon interactions in the delafossite PdCoO${}_2$: From weak bulk to polaronic surface coupling
• Disorder-enhanced effective masses and deviations from Matthiessen's rule in PdCoO${}_2$ thin films
• Concurrence of directional Kondo transport and incommensurate magnetic order in the layered material AgCrSe${}_2$
• Multipolar Fermi Surface Deformations in Sr${}_2$RuO${}_4$ Probed by Resistivity and Sound Attenuation: A Window into Electron Viscosity and the Collision Operator
• Universality in Non-Equilibrium Quantum Systems
• In situ modification of delafossite type PdCoO2 bulk single crystal for reversible hydrogen sorption and fast hydrogen evolution
• Novel electronic state of honeycomb iridate Cu${}_2$IrO${}_3$ at high pressure
• Control of Impurity Phase Segregation in a PdCrO${}_2$/CuCrO${}_2$ Heterostructure
• Topological bands in metals
• Revisiting the metal-to-metal transition in $2H$-AgNiO${}_2$
• Electron-phonon origins of unconventional resistivity in moderately correlated perovskite oxides
• Twin-domain formation in epitaxial triangular lattice delafossites
• Layer-Resolved Many-Electron Interactions in Delafossite PdCoO2 from Standing-Wave Photoemission Spectroscopy