Optimisation of pulsed laser deposited Ba_(1-x)K_(x)BiO_(3)thin films with tunable superconducting properties by control of K doping level,x  

作　　者：A.Kursumovic J.Prestigiacomo M.de h-Óra W.Li J.Feighan V.Smolyaninova I.Smolyaninov M.Osofsky J.L.MacManus-Driscoll 

机构地区：[1]Department of Materials Science and Metallurgy,University of Cambridge,CB3 OFS Cambridge,United Kingdom [2]Department of Physics Astronomy and Geosciences Towson University,8000 York Rd.,Towson,MD 21252,USA [3]Materials Science and Technology Division,Naval Research Laboratory,Washington DC,20375,USA [4]Saltenna LLC,1751 Pinnacle Dr.Ste.600,McLean,VA 22102-4007 USA

出　　处：《Superconductivity》2024年第3期66-72,共7页超导（英文）

基　　金：All the authors thank the ONRG-NICOP-N62909-18-1-2092 grant for funding this research;Muireann de h-Óra also thanks European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement number 861145–BeMAGIC for financial support;Judith L.MacManus-Driscoll also thanks the Royal Academy of Engineering Chair in Emerging Technologies grant-CIET1819\24 and the ERC grant EU-H2020-ERC-ADG#882929 EROS.

摘　　要：The mid-T_(C) superconductor Ba1-XKXBiO3(BKBO)exhibits different superconducting mechanisms depending on x,in the range∼0.35–0.65.The optimal doping for the highest T_(C) is reported to be around x=0.4.To understand more about the dependence of the superconducting mechanism on x,high quality and reproducible epitaxial films with controlled x are needed.This has been challenging owing to the volatility of K and(to a lesser extent)Bi.In this work,we use pulsed laser deposition(PLD)with several novel process steps to achieve high-quality films in a reproducible way.These include a modified method for target preparation,a low NO_(2) growth pressure,and precise positioning of substrates in the PLD plume.Optimum T_(C) films(32 K onset)were grown from an x=0.4 target,i.e.with no excess K,as is normally used.Stable,higher K content films(made from an x=0.45 target),were also grown.These x=0.45 films had a lower T_(C) (22.5 K onset),as expected for(K)overdoped films,with very high upper critical field,H_(C2) (0 K),and irreversibility field,Hirr(0 K),values,from linear extrapolation,of∼31.7 T and∼28.8 T,respectively.The growth methodology demonstrated in this work is highly beneficial for fundamental mechanistic studies of this complex superconductor on which there is renewed interest,and where controlled compositions and crystalline quality are currently limited.

关 键 词：DOPING SUPERCONDUCTOR SUPERCONDUCTING 

分 类 号：O48[理学—固体物理]