Abstract
Modulation of the superconducting state possessing a C-type antiferromagnetic phase in the Nd0.35Sr0.65MnO3/YBa2Cu3O7 heterostructure is investigated, with the Nd0.35Sr0.65MnO3 thickness (t) varying from 40 to 200 nm. Both the superconducting transition temperature and the upper critical field along the c-axis decrease with increasing t; while the in-plane coherence length increases from 2.0 up to 3.6 nm. Meanwhile, the critical current density exhibits a field-independent behavior, indicating an enhanced flux pinning effect. Furthermore, low-temperature spin canting induces a breakdown and re-entrance of the superconductivity, demonstrating a dynamic completion between the superconducting pairing and the exchange field. An unexpected colossal magnetoresistance is observed below the superconducting re-entrance temperature at t = 200 nm, which is attributed to the dominant influence of the exchange field over the pairing energy.
Highlights
Investigating the proximity effect between different ordered phases provides unique opportunities to study fundamental physics as well as new phenomena for applications[1,2,3,4,5]
We observe a change of sign in the magnetoresistance of YBCO/NSMO when NSMO reaches t = 200 nm, which involves a thickness-dependent competition between the exchange energy and the condensation energy of the Cooper pairs
According to the X-ray diffraction (XRD) analysis, the c-lattice parameter for a single layer of YBCO film is 11.691 Å, which is slightly larger than the bulk values of YBCO (c = 11.6701 Å, a = 3.8820 Å, b = 3.8148 Å; orthorhombic structure; space group: Pmmm)
Summary
Investigating the proximity effect between different ordered phases provides unique opportunities to study fundamental physics as well as new phenomena for applications[1,2,3,4,5]. The reason NSMO has considerable effect upon YBCO is that NSMO is not an isotropic antiferromagnet (G-type) but is a C-type antiferromagnet, meaning that the Mn moment aligns parallel along the c-axis in one-dimensional space and compensates for the neighboring c-axis spin chain with opposite spins The competition between this one-dimensional FM interaction along the c-axis and the two-dimensional AFM interaction in the ab-plane is very delicate and is sensitive to temperature and/or strain, and is the reason that the canted AFM state appears at a low temperature. We observe a change of sign in the magnetoresistance of YBCO/NSMO when NSMO reaches t = 200 nm, which involves a thickness-dependent competition between the exchange energy and the condensation energy of the Cooper pairs This result demonstrates the possibility of using heterostructures of superconducting and canting phases to design a type of spintronic switch
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