Magnetic proximity effect in YBCO/STO/LCMO multilayers

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Date
2016-11-29
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Publisher
Australian Institute of Nuclear Science and Engineering
Abstract
Tailoring of the electronic properties of complex oxide heterostructures, thin films, and superlattices with atomically sharp interfaces is at the frontline of materials research at present [1, 2, 3]. Interfaces exhibit novel states that are not possible in bulk materials as a result of broken symmetry, induced strains, and modified exchange interactions. In this work we examined the interaction between a superconducting YBa2Cu3O7-δ thin filmlayer and a ferromagnetic La2/3Ca1/3MnO3 layer using polarised neutron reflectometry. The interaction at the interface between YBCO/LCMO multilayers has resulted in a variety of observed phenomena such as induced ferromagnetic moments in YBCO layers that are antiparallel to neighbouring LCMO layers, and a strong reduction in magnetization in LCMO near the interface. Prajapat et al. investigated the YBCO/LCMO interface using SrTiO3(STO) as an intermediate insulating layer, and reported that the magnetic depletion (MD) in LCMO near the interface is dependent on the critical temperature of YBCO and the thickness of the LCMO layer, indicating that the origin of the MD in LCMO is due to Cooper pairs tunneling through the STO interlayer across the interface [5]. Our work has verified the observation of the MD layer in LCMO near the interface as claimed in the past report, and additionally studied the effect of a magnetic field on this layer. Polarised neutron reflectometry measurements performed at ANSTO on the PLATYPUS reflectometer indicate that the effect of applying fields at 0.03 T and 1 T is to cause a small restoration of magnetization in this depleted layer. This result supports the mechanism proposed by Prajapat et al. of superconductivity-induced MD from tunnelling through STO.
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Keywords
Electronic structure, Thin films, Superlattices, Superconductivity, Ferromagnetism, Magnetization, Copper pairs, Tunnel effect, ANSTO, Neutron reflectors
Citation
Paull, O., Causer, G., Pan, A., & Klose, F. (2016). Magnetic proximity effect in YBCO/STO/LCMO multilayers. Paper presented at 13th AINSE-ANBUG Neutron Scattering Symposium, Sydney, NSW, Australia, 29-30 November 2016.