Andreev spectroscopy of CrO2 thin films on TiO2 and Al2O3

  title={Andreev spectroscopy of CrO2 thin films on TiO2 and Al2O3},
  author={Karen A. Yates and M S Anwar and Jan Aarts and O. Conde and M Eschrig and Tomas Lofwander and LF Cohen},
Here we analyse the spectroscopic information gathered at a number of single CrO2/Pb interfaces. We examine thin films requiring additional interfacial layers to generate long-range spin triplet proximity effect superconductivity (CrO2/TiO2) or not (CrO 2/Al2O3). We analyse the data using two theoretical models and explore the use of a parameter-free method to determine the agreement between the models and experimental observations, showing the necessary temperature range that would be required… Expand
8 Citations
Magnetic properties and thermal stability of Ti-doped CrO2 films
Abstract Chromium dioxide (CrO2) is a striking half metal material which may have important applications in the field of spintronics. However, pure CrO2 film is metastable at room temperature and theExpand
Giant thermoelectric effects in a proximity-coupled superconductor-ferromagnet device
The usually negligibly small thermoelectric effects in superconducting heterostructures can be boosted dramatically due to the simultaneous effect of spin splitting and spin filtering. Building on anExpand
Andreev reflection spectroscopy in transition metal oxides
  • K. Yates, L. Cohen
  • Medicine, Materials Science
  • Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
  • 2018
The practicality of utilization of the current models for determination of the transport current spin polarization and the evidence for Andreev bound states are discussed. Expand
First-principles study of the metal-insulator transition in the Ti-substituted rutile CrO2
Abstract The effect of Ti-substitution for Cr in CrO2 is extensively studied by employing first-principles electronic structure calculations. The host material is a ferromagnetic half-metal. ThisExpand
Spin-polarized supercurrents for spintronics: a review of current progress.
  • M. Eschrig
  • Physics, Medicine
  • Reports on progress in physics. Physical Society
  • 2015
This report follows recent developments in the controlled creation of long-range equal-spin triplet supercurrents in ferromagnets and its contribution to spintronics. Expand
Interfacial Spin-Orbit Coupling: A Platform for Superconducting Spintronics
Spin-orbit coupling (SOC) is a key interaction in spintronics, allowing an electrical control of spin or magnetization and, vice versa, a magnetic control of electrical current. However, recentExpand
Theory of Andreev bound states in S-F-S junctions and S-F proximity devices
  • M. Eschrig
  • Physics, Medicine
  • Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
  • 2018
This article provides a general framework for non-local Andreev phenomena in systems involving superconductors and ferromagnets with strong spin-polarization in terms of coherence functions, and shows how the latter link wave function and Green-function based theories. Expand
General boundary conditions for quasiclassical theory of superconductivity in the diffusive limit: Application to strongly spin-polarized systems
Boundary conditions in quasiclassical theory of superconductivity are of crucial importance for describing proximity effects in heterostructures between different materials. Although they have beenExpand


Long range spin supercurrents in ferromagnetic CrO2 using a multilayer contact structure
We report measurements of long ranged supercurrents through ferromagnetic and fully spin-polarized CrO2 deposited on TiO2 substrates. In earlier work, we found supercurrents in films grown onExpand
Is CrO2 fully spin polarized? Analysis of Andreev spectra and excess current.
The spectra can be well understood within a model of fully spin-polarized bands in CrO2 together with spin-active scattering at the contact, in contrast to analysis of the data within extended Blonder-Tinkham-Klapwijk models. Expand
Influence of Growth Temperature and Carrier Flux on the Structure and Transport Properties of Highly Oriented CrO2 on Al2O3 (0001)
In this work we report on the structure and magnetic and electrical transport properties of CrO2 films deposited onto (0001) sapphire by atmospheric pressure (AP)CVD from a CrO3 precursor. Films areExpand
Inducing supercurrents in thin films of ferromagnetic CrO2
It is becoming gradually clear that it is possible to induce superconducting correlations in ferromagnets by generating so-called odd-frequency triplet Cooper pairs, which have two equal (rather thanExpand
Long-range supercurrents through half-metallic ferromagnetic CrO2
We report on measurements of supercurrents through the half-metallic ferromagnet CrO2 grown on hexagonal Al2O3 (sapphire). The current was observed to flow over a distance of 700 nm between twoExpand
The spin polarization of CrO2 revisited
Here, we use Andreev reflection spectroscopy to study the spin polarization of high quality CrO2 films. We study the spin polarization as a function of growth temperature, resulting in grain size andExpand
Observation of spin-triplet superconductivity in Co-based Josephson junctions.
Experimental observations provide strong evidence for induced spin-triplet pair correlations, which have been predicted to occur in superconducting-ferromagnetic hybrid systems in the presence of certain types of magnetic inhomogeneity. Expand
Spin-dependent transparency of ferromagnet/superconductor interfaces.
This work critically evaluates the use of an extended Blonder-Tinkham-Klapwijk (BTK) model to extract values of the spin polarization for ferromagnetic metals from measurements of point-contact Andreev reflection (AR) generalized to spin-polarized systems. Expand
Spin polarization of (Ga,Mn)As measured by Andreev Spectroscopy : The role of spin-active scattering
We investigate the spin polarization of the ferromagnetic semiconductor (Ga,Mn)As by point-contact Andreev reflection spectroscopy. The conductance spectra are analyzed using a recent theoreticalExpand
Coexistence of universal and topological anomalous hall effects in metal CrO2 thin films in the dirty limit.
The scaling exponent of 1.6 between anomalous Hall and longitudinal conductivity, characteristic of the universal Hall mechanism in dirty-metal ferromagnets, emerges from a series of CrO2 films as the authors systematically increase structural disorder, suggesting that the universal term is more prevalent than previously realized. Expand