Emerging Diluted Ferromagnetism in High-TcSuperconductors Driven by Point Defect Clusters.
Defects in ceramic materials are generally seen as detrimental to their functionality and applicability. Yet, in some complex oxides, defects present an opportunity to enhance some of their properties or even lead to the discovery of exciting physics, particularly in the presence of strong correlations. A paradigmatic case is the high-temperature superconductor YBa2Cu3O7-δ(Y123), in which nanoscale defects play an important role as they can immobilize quantized magnetic flux vortices. Here previously unforeseen point defects buried in Y123 thin films that lead to the formation of ferromagnetic clusters embedded within the superconductor are unveiled. Aberration-corrected scanning transmission microscopy has been used for exploring, on a single unit-cell level, the structure and chemistry resulting from these complex point defects, along with density functional theory calculations, for providing new insights about their nature including an unexpected defect-driven ferromagnetism, and X-ray magnetic circular dichroism for bearing evidence of Cu magnetic moments that align ferromagnetically even below the superconducting critical temperature to form a dilute system of magnetic clusters associated with the point defects.
Institut de Ciència de Materials de Barcelona Barcelona 08193 Spain.
Jaume
J
Gazquez
Institut de Ciència de Materials de Barcelona Barcelona 08193 Spain.
Roger
R
Guzman
Department of Physics and Astronomy Vanderbilt University Nashville TN 37235 USA; Materials Science and Technology Division Oak Ridge National Laboratory Oak Ridge TN 37831 USA; Department of Mechanical Engineering and Materials Science Washington University in St. Louis St. Louis MO 63130 USA.
Rohan
R
Mishra
Escola Universitària Salesiana de Sarrià Barcelona 08017 Spain.
Elena
E
Bartolomé
Materials Science and Technology Division Oak Ridge National Laboratory Oak Ridge TN 37831 USA; Universidad Complutense de Madrid Madrid 28040 Spain.
Juan
J
Salafranca
Laboratorio de Microscopías Avanzadas Instituto de Nanociencia de Aragón - ARAID Universidad de Zaragoza Zaragoza 50018 Spain.
Cesar
C
Magén
Materials Science and Technology Division Oak Ridge National Laboratory Oak Ridge TN 37831 USA; Universidad Complutense de Madrid Madrid 28040 Spain.
Maria
M
Varela
Institut de Ciència de Materials de Barcelona Barcelona 08193 Spain.
Mariona
M
Coll
Institut de Ciència de Materials de Barcelona Barcelona 08193 Spain.
Anna
A
Palau
ALBA Synchrotron Light Source Cerdanyola del Valles 08290 Spain.
S Manuel
SM
Valvidares
ALBA Synchrotron Light Source Cerdanyola del Valles 08290 Spain.
Pierluigi
P
Gargiani
ALBA Synchrotron Light Source Cerdanyola del Valles 08290 Spain.
Eric
E
Pellegrin
ALBA Synchrotron Light Source Cerdanyola del Valles 08290 Spain.
Javier
J
Herrero-Martin
Department of Materials Science and Engineering National University of Singapore Singapore 117574 Singapore.
Stephen J
SJ
Pennycook
Department of Physics and Astronomy Vanderbilt University Nashville TN 37235 USA; Materials Science and Technology Division Oak Ridge National Laboratory Oak Ridge TN 37831 USA.
Sokrates T
ST
Pantelides
Institut de Ciència de Materials de Barcelona Barcelona 08193 Spain.
Teresa
T
Puig
Institut de Ciència de Materials de Barcelona Barcelona 08193 Spain.
Xavier
X
Obradors
STEM‐EELS; XMCD; magnetism; nanostructures; superconductivity