The unconventional doping in YBa2Cu3O7−x/La0.7Ca0.3MnO3 heterostructures by termination control

Abstract

In strongly correlated oxides, heterostructures provide a powerful route to manipulate the charge, spin, orbital, and lattice degrees of freedom to create distinctive functionalities. In this work, we have achieved atomically precise interface control in YBa2Cu3O7−x/La0.7Ca0.3MnO3 (YBCO/LCMO) heterostructures and find a hidden effective doping. This mechanism is responsible for higher Tc in the sample with the MnO2-terminated interface than in that with the La0.7Ca0.3O-terminated interface. The MnO2-terminated sample also shows a larger magnetic moment of Mn together with a lower valence state. For more than a decade, the control of Tc in these heterostructures prior to this work has been solely via the variation of YBCO or LCMO thickness. This work hints at an alternative way of exploiting and exploring the interactions between superconductivity and magnetism in this system.

The Route to Supercurrent Transparent Ferromagnetic Barriers in Superconducting Matrix

“…In contrast, the profile for the (110)-oriented SFS shows more irregularities and a larger variation of the Mn L 3 /L 2 ratio across the layers. These differences may be attributed to substantially different interface structures in these two cases, in particular, different ways the CuO x planes are connected to the interface, which determines different a charge transfer across the interface. , The proposed detailed structure of the interfaces can be found in the Supporting Information.…”

Interface Magnetism in La0.7Ca0.3MnO3/PrBa2Cu3O7 Epitaxial Heterostructures

“…This technique has shown to produce oxide heterostructures with highly perfect interfaces . Both manganite interfaces were MnO 2 terminated, what has been proposed to yield larger Tc and larger magnetic moment than for LaCaO terminated ones . Previous studies of polarized neutron reflectometry in magnetic tunnel junctions (MTJs) have evidenced large (close to bulk) values of the magnetic moments of top and bottom layers.…”

Magnetic Field Enhancement in Critical Current and Possible Triplet Superconductivity in LSMO/YBCO/LSMO Heterostructures

“…The Cu moment shows a strong coupling with the Mn moment across the interface via d z 2 orbital reconstruction even when the interface has a finite thickness. The interface thickness can be a natural structure barrier by employing the various terminations of the contact layer in a controlled growth manner , or inserting an insulating layer . The induced Cu moment is antiparallel to the Mn moment under zero or low magnetic field conditions and could flip when a higher magnetic field is applied. , The interface thickness, or termination, and the thickness of the YBCO layer affect the charge transfer and indirectly change the superconducting transition temperatures .…”

“…The interface thickness can be a natural structure barrier by employing the various terminations of the contact layer in a controlled growth manner , or inserting an insulating layer . The induced Cu moment is antiparallel to the Mn moment under zero or low magnetic field conditions and could flip when a higher magnetic field is applied. , The interface thickness, or termination, and the thickness of the YBCO layer affect the charge transfer and indirectly change the superconducting transition temperatures . Besides, how the physical properties changed with the induced Cu moment and the interface conditions are still unknown.…”