Strong correlation between flux pinning and epitaxial strain in the GdBa₂Cu₃O_7−x/La_0.7Sr_0.3MnO₃ nanocrystalline heterostructure

Abstract

The effect of magnetic flux pinning is investigated in GdBa2Cu3O7 (GdBCO) thin films with two different types of ferromagnetic La0.7Sr0.3MnO3 (LSMO) buffers (nanoparticles and a layer) deposited on an STO substrate.

Interface Effects on Magnetic Flux Pinning in La0.7Sr0.3MnO3/YBa 2Cu3O7–x Bilayers

“…Surely, the q parameter plays an important role in suppressing the overall superconductivity with a magnetic field. Oh et al 26 have shown that flux pinning in the FM/SC heterostructure is governed by the interaction of vortices with pinning sites induced by structural defects in addition to magnetic pinning. The structural disorder of the CuO 2 planes at the interface due to coupling between the FM and SC layer acts as additional pinning mechanism.…”

Enhancement in High-Field Jc Properties and the Flux Pinning Mechanism of ZnO-Buffered MgB2 Films

“…The slopes of the double logarithmic functions of PSD, which are related to the growth mode of the samples, show no significant difference with α values of 3.14 ± 0.03, indicating identical growth conditions for all samples. 37 In contrast, the ZnO53 sample exhibits a distinct feature, despite having a similar slope, it has a longer power law region; thus, it reaches a plateau at a higher frequency of 0.5 nm −1 . The higher spatial frequency of the slope and larger area under the PDS function translates to a larger number of grain boundaries in the surface morphology.…”

“…The image matrices were analyzed using the power spectra distribution (PSD) function to find the periodicity of surface morphology; the result of the PSD analyses is shown in Figure d. The slopes of the double logarithmic functions of PSD, which are related to the growth mode of the samples, show no significant difference with α values of 3.14 ± 0.03, indicating identical growth conditions for all samples . In contrast, the ZnO53 sample exhibits a distinct feature, despite having a similar slope, it has a longer power law region; thus, it reaches a plateau at a higher frequency of 0.5 nm –1 .…”

Tuning Flux Pinning in GdBa2Cu3O7–x/La0.7Sr0.3MnO3 Epitaxial Bilayers via Substrate-Induced Strain

“…We examined whether the structural distortion of LSMO by different substrates has an effect on the GdBCO matrix. The average Cu–O bond lengths are calculated from the Cu K-edge EXAFS data in Figure c using the same method as conducted in previous paper, , and the results are compared in Figure d,e. In the case of GdBCO/LSMO/STO, the Cu–O bond length is nearly constant to be 1.915 Å, shorter than that of the pure sample.…”

“…The series of GdBa 2 Cu 3 O 7– x (GdBCO)/La 0.7 Sr 0.3 MnO 3 (LSMO) bilayers are fabricated on single crystal SrTiO 3 (STO) and LaAlO 3 (LAO) (100) substrates using a pulsed laser deposition (PLD) technique (KrF excimer laser, LPX pro240, 248 nm). The details of the fabrication process can be found in our previous works. , The thickness of the GdBCO layer is fixed to be about 400 nm, where the T c value is optimized, in consideration of the application of high -T c superconductors, and the thickness of the LSMO layer varies as x = 25, 50, and 100 nm on STO and as y = 20, 40, 50, and 80 nm on the LAO substrate. Depending upon the thickness of the LSMO and substrate, the samples are denoted as pure, S x ( x = 25, 50, and 100), and L y ( y = 20, 40, 50, and 80).…”