Scanning tunneling spectroscopy study of c-axis proximity effect in epitaxial bilayer manganite/cuprate thin films

被引：20
作者：
Fridman, I. [1 ]
Gunawan, L. [2 ]
Botton, G. A. [2 ]
Wei, J. Y. T. [1 ,3 ]
机构：
[1] Univ Toronto, Dept Phys, Toronto, ON M5S 1A7, Canada
[2] McMaster Univ, Brockhouse Inst Mat Res, Hamilton, ON L8S 4M1, Canada
[3] Canadian Inst Adv Res, Toronto, ON M5G 1Z8, Canada
来源：
PHYSICAL REVIEW B | 2011年 / 84卷 / 10期
基金：
加拿大自然科学与工程研究理事会;
关键词：
SUPERCONDUCTOR-FERROMAGNET STRUCTURES; METAL-INSULATOR-TRANSITION; TRANSPORT; INTERFACE;
D O I：
10.1103/PhysRevB.84.104522
中图分类号：
T [工业技术];
学科分类号：
08 ;
摘要：
Recent experimental studies have indicated novel superconducting proximity effects in thin-film heterostructures comprising ferromagnetic manganites and superconducting cuprates. To look for such effects microscopically, we performed scanning tunneling spectroscopy on La(2/3)Ca(1/3)MnO(3)/YBa(2)Cu(3)O(7-delta) (LCMO/YBCO) bilayer thin films. c-axis-oriented films of varying thickness were grown on SrTiO(3) substrates using pulsed laser-ablated deposition. Heteroepitaxiality of the films was confirmed by cross-sectional transmission electron microscopy. Tunneling spectra were measured at 4.2 K and analyzed for signatures of a pairing gap on the LCMO layer. For bilayer samples with LCMO thickness down to 5 nm, asymmetric conductance spectra characteristic of single-layer LCMO films were observed, showing no clear gap structures. These observations are consistent with a very short-range proximity effect involving spin-singlet pairs, and difficult to reconcile with longer-range proximity scenarios involving spin-triplet pairs.
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页数：4
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