Searcharxiv⌕ Search
Home/Archive/arXiv

arXiv · cond-mat/0508753

Signature of a crossed Andreev reflection effect (CARE) in the magnetic response of YBCO junctions with the itinerant ferromagnet SrRuO_3

P. Aronov·G. Koren
View original source ↗Read source document ↗Export metadata ↓

Abstract

Magnetic properties of SFS and SF ramp-type junctions with $YBa_2Cu_3O_{7-δ}$ (YBCO) electrodes (S), and the itinerant ferromagnet $SrRuO_3$ (SRO - F), were investigated. We looked for a crossed Andreev reflection effect (CARE) in which an electron from one magnetic domain in F is Andreev reflected as a hole into an adjacent, oppositely polarized, domain while a pair is transmitted into S. CARE is possible in SRO since the width of its domain walls is of the order of the YBCO coherence length (2-3 nm). Our junctions behave as typical magnetic tunneling junctions, as the conductance spectra were always asymmetric, and a few showed bound state peaks at finite bias that shifted with field according to the classical Tedrow and Meservey theory. In many of our SFS junctions with a barrier thickness of 10-20 nm, a prominent zero bias conductance peak (ZBCP) has been observed. This peak was found to decrease \textit{linearly} with magnetic field, as expected for Andreev and CARE scattering. In contrast, in SF junctions, the observed ZBCP was found to decrease versus field almost \textit{exponentially}, in agreement with the Anderson-Appelbaum theory of scattering by magnetic states in F. Thus, transport in our SFS and SF junctions depends strongly on the size of the F layer. We also found that in both cases, the ZBCP height at zero field decreased with increasing magnetic order of the domains in F, in agreement with the CARE mechanism.

Explore related subjects

cond-mat.supr-concond-mat.str-el

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

P. Aronov, G. Koren. 2005-08-31. Signature of a crossed Andreev reflection effect (CARE) in the magnetic response of YBCO junctions with the itinerant ferromagnet SrRuO_3. https://doi.org/10.1103/physrevb.72.184515

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Same-spin correlation screens the exchange peak of the electron gas near 2kF

Exchange alone gives the electron gas a local field factor with a sharp peak just below 2kF. Quantum Monte Carlo finds none. Both spin channels are computed here from their lowest diagrams with a dynamically screened interaction and no fitting. Parallel spin correlation is the negative image of exchange and removes about half the peak; the calculated spin-resolved factors account for the QMC data at rs = 1 and 2, and at q = 0 for the compressibility and spin susceptibility obtained from the ground-state energy. The two classes of diagrams are the two terms of the kernel of Hedin's vertex equation, of which the second is routinely dropped.

cond-mat.supr-con↗
arXiv2026

Local Josephson response near nonmagnetic impurities and vortices in a two-orbital $s_{\pm}$ superconductor

We study the local Josephson response near nonmagnetic impurities and vortices in a self-consistent two-orbital $s_{\pm}$ superconductor. For a local $s$-wave tip that couples equally to the two orbitals, anomalous spectral contributions of opposite sign nearly cancel in the clean sample. Nonmagnetic impurities redistribute these contributions and can reverse the local coupling without a corresponding $π$ phase shift of the bond pair fields. Negative coupling appears at off-center sites at weaker impurity potentials than at the impurity site. The impurity-induced change is concentrated at lower quasiparticle energies, while states over a broader energy range contribute to the total clean and impurity couplings. In zero field, the coupling also changes sign as the tip gap is varied, and increasing the tunneling strength can reverse the $m=1$ sine component of the current without changing the sample state. At the chosen coherence-peak energy, increasing impurity strength mainly changes the relative intensities of existing quasiparticle-interference features. In a self-consistent two-vortex state, the Josephson response develops a spatially varying phase relative to the condensate. The response and condensate share the winding close to each core, while larger loops enclose additional winding of the Josephson response. The local Josephson sign and phase reflect the anomalous spectrum and the tip--sample coupling.

cond-mat.supr-con↗
arXiv2026

Thermalization-Controlled Superconducting Diode-Like Transport in Disordered Molybdenum and NbN Thin Films

Superconducting diode effects are characterized by direction-dependent critical currents in the superconducting state. Here, we investigate diode-like transport in 128-nm-thick Mo thin film deposited on Si_SiO2 substrate by DC magnetron sputtering. The thin film exhibit a superconducting transition temperature TC of 5.8 K. Pronounced current-direction asymmetry and hysteresis are observed in current-voltage characteristics measured in a closed-cycle refrigerator. In contrast, the same thin film exhibits a substantially more symmetric response in a 14T cryogenic system with improved sample thermalization. We attribute this strong dependence on the measurement environment to electrothermal effects arising from current-induced Joule heating and finite thermal relaxation. As the current approaches the superconducting-to-resistive switching condition, the emergence of a resistive component leads to a rapid increase in Joule heating, raising the sample temperature and modifying the switching condition. Conversely, during the resistive-to-superconducting transition, residual heating and finite thermal relaxation reduce the switching current. Since P is equal to I2R it is independent of current polarity, the observed asymmetry is not associated with polarity-dependent Joule heating but with the interplay of thermal relaxation, sweep history, and thermal boundary conditions. The suppression of the asymmetry under improved thermalization, together with similar behavior observed in NbN reference films, indicates that the apparent diode-like response is strongly influenced by electrothermal effects. These results highlight the need to distinguish thermal switching and hysteresis from intrinsic nonreciprocal superconductivity when identifying superconducting diode effects in transport measurements.

cond-mat.supr-con↗