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Title: On the Origin of Enhanced Critical Current Density and Thermal-Activated Flux Flow in K{sub x}Fe{sub 2−y}Se{sub 2} Superconductors: the Effect of Quenching and Mn Doping

Abstract

A magnetotransport, vortex pinning, and critical current density study of superconducting K{sub 0.8}Fe{sub 2−z}Mn{sub z}Se{sub 2} (z = 0, 0.02) single crystals is reported. The parameters of upper critical field, coherence length, and anisotropic ratio at 0 K are presented. Based on thermally activated flux flow model, the values of pinning potential, U{sub 0}{sup ∥{sub c}}(U{sub 0}{sup ∥{sub a}{sub b}}), at 0.25 T are derived to be as large as 1.3 × 10{sup 4}(1.8 × 10{sup 4}) K for z = 0.02, which shows rather robust and retains still larger than pure ones up to 9 T. Utilizing scanning electron microscope, it is revealed the increased magnitude of magnetic moment in magnetic hysteresis loops correlates well with the crystal morphology variation. The evidence on the inhomogeneous distribution of Mn dopants between the matrix and stripe phase is also shown. Furthermore, the temperature dependence of critical current density is analyzed by different pinning regimes and the model of granular superconductor. It is demonstrated that the Josephson coupling between superconducting grains exists in quenched K{sub 0.8}Fe{sub 2−y}Se{sub 2}. However, for Mn-doped sample, the Mn dopant can induce strong vortex pinning in the form of fine K–Mn–Se inclusions.

Authors:
;  [1]
  1. Shanghai University, Department of Physics (China)
Publication Date:
OSTI Identifier:
22782477
Resource Type:
Journal Article
Journal Name:
Journal of Superconductivity and Novel Magnetism
Additional Journal Information:
Journal Volume: 31; Journal Issue: 8; Other Information: Copyright (c) 2018 Springer Science+Business Media, LLC, part of Springer Nature; http://www.springer-ny.com; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1557-1939
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANISOTROPY; COHERENCE LENGTH; CRITICAL CURRENT; CRITICAL FIELD; DOPED MATERIALS; FLOW MODELS; IRON COMPOUNDS; MAGNETIC MOMENTS; MANGANESE ADDITIONS; MONOCRYSTALS; POTASSIUM COMPOUNDS; SCANNING ELECTRON MICROSCOPY; SELENIUM COMPOUNDS; SUPERCONDUCTORS; TEMPERATURE DEPENDENCE

Citation Formats

Fang, Y. F., E-mail: yifei-fang@fudan.edu.cn, and Li, M. T., E-mail: mingtaoli04@gmail.com. On the Origin of Enhanced Critical Current Density and Thermal-Activated Flux Flow in K{sub x}Fe{sub 2−y}Se{sub 2} Superconductors: the Effect of Quenching and Mn Doping. United States: N. p., 2018. Web. doi:10.1007/S10948-017-4525-3.
Fang, Y. F., E-mail: yifei-fang@fudan.edu.cn, & Li, M. T., E-mail: mingtaoli04@gmail.com. On the Origin of Enhanced Critical Current Density and Thermal-Activated Flux Flow in K{sub x}Fe{sub 2−y}Se{sub 2} Superconductors: the Effect of Quenching and Mn Doping. United States. https://doi.org/10.1007/S10948-017-4525-3
Fang, Y. F., E-mail: yifei-fang@fudan.edu.cn, and Li, M. T., E-mail: mingtaoli04@gmail.com. 2018. "On the Origin of Enhanced Critical Current Density and Thermal-Activated Flux Flow in K{sub x}Fe{sub 2−y}Se{sub 2} Superconductors: the Effect of Quenching and Mn Doping". United States. https://doi.org/10.1007/S10948-017-4525-3.
@article{osti_22782477,
title = {On the Origin of Enhanced Critical Current Density and Thermal-Activated Flux Flow in K{sub x}Fe{sub 2−y}Se{sub 2} Superconductors: the Effect of Quenching and Mn Doping},
author = {Fang, Y. F., E-mail: yifei-fang@fudan.edu.cn and Li, M. T., E-mail: mingtaoli04@gmail.com},
abstractNote = {A magnetotransport, vortex pinning, and critical current density study of superconducting K{sub 0.8}Fe{sub 2−z}Mn{sub z}Se{sub 2} (z = 0, 0.02) single crystals is reported. The parameters of upper critical field, coherence length, and anisotropic ratio at 0 K are presented. Based on thermally activated flux flow model, the values of pinning potential, U{sub 0}{sup ∥{sub c}}(U{sub 0}{sup ∥{sub a}{sub b}}), at 0.25 T are derived to be as large as 1.3 × 10{sup 4}(1.8 × 10{sup 4}) K for z = 0.02, which shows rather robust and retains still larger than pure ones up to 9 T. Utilizing scanning electron microscope, it is revealed the increased magnitude of magnetic moment in magnetic hysteresis loops correlates well with the crystal morphology variation. The evidence on the inhomogeneous distribution of Mn dopants between the matrix and stripe phase is also shown. Furthermore, the temperature dependence of critical current density is analyzed by different pinning regimes and the model of granular superconductor. It is demonstrated that the Josephson coupling between superconducting grains exists in quenched K{sub 0.8}Fe{sub 2−y}Se{sub 2}. However, for Mn-doped sample, the Mn dopant can induce strong vortex pinning in the form of fine K–Mn–Se inclusions.},
doi = {10.1007/S10948-017-4525-3},
url = {https://www.osti.gov/biblio/22782477}, journal = {Journal of Superconductivity and Novel Magnetism},
issn = {1557-1939},
number = 8,
volume = 31,
place = {United States},
year = {Wed Aug 15 00:00:00 EDT 2018},
month = {Wed Aug 15 00:00:00 EDT 2018}
}