Copyright IOP SC02 2015-2016
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Research results:

1. The best metastable phase electron-doped superconducting single crystal thin film (La2-xCexCuO4 system) is developed internationally and the nature of electronic interaction closely related to unconventional superconductivity is revealed through exerting magnetic field, electric field and controlling the composition:



Employing ionic liquids transistor technology, the first electric field regulation is made on the e-doped cuprate ultra thin film. It is found that numbers of electron and hole carriers increase or decrease in the sae time under the regulation of the electrostatic field, which supports Tao Xiang’s dual- band explanation based on t-U'-J model [Sci. Rep. 6, 26642 (2016)].


The second quantum fluctuation phenomena is discovered, which is associated with the superconducting boundary. This is confirmed from different aspects.[PNAS 109, 8440 (2012)]
Our experiments clarified the problem where the boundary of the antiferromagnetic order is [Nat.Commun.6,6041(2015)], which added more details to the electronic phase diagram.


The first complete 3D electron-doped phase diagram in the over-doped region is established for La2-xCexCuO4, ever since electron-doped superconductor family was found in 1989. It is the first time that a complete understanding of the over-doped region has been achieved. When the superconducting state is suppressed by exerting magnetic field, the behavior of electron transport about normal state exhibites "strange metal" feature at very low temperature. Therefore the conventional quantum critical image is overturned and an important new understanding arose [Nature 476 73(2011)]. The results support the theory that the superconductivity of electron-doped cuprate relates to antiferromagnetic spin fluctuations.




2. It is found that high-temperature superconducting electron is closely related to spin density fluctuation by our comparative study of three types of unconventional superconducting system (single crystal thin film or single crystal bulk). This research provides experimental facts for the understanding of unconventional superconducting electron pairing mechanism.




The first complete phase diagram of titanium spinel oxide superconductor LiTi2O4 is made based on electron transport and tunneling spectroscopy study of single-crystal thin film samples. It is found that the spin fluctuations zone separates with superconducting phase region [Nat.Commun.6,7183 (2015)], which may be one of the reasons why high-temperature superconductivity of LiTi2O4 does not appear.


[1] Method for preparing combined thin film ZL201310413317.3
[2] Elastic probe array multi-channel resistance measurement method and device ZL201310422062.7
[3] Preparation method of multicomponent combined membrane ZL201310413316.9
[4] Powder sheeting mould ZL201520205972.4
[5] Probe type transport detecting system ZL201520127897.4
[6] Combined thin film preparation device and method ZL201410128987.5
[7] Wide-temperature area tunable microwave device based on combined thin film ZL201410026262.5
[8] Preparation method of layered cross capacitance and layered cross capacitance 201410425900.0
[9] Electrical connecting device for transport measurement 2015104083120.0
[10] Multi-degree of freedom rotatable probe 201510303162.7
[11] Preparation and in-situ measurement system for combined thin film 201510446068.7
[12] Position device for sample holder 2015105248417.0



3. The technology which combines the high -throughput syntheses and rapid characterization of thin film is developed in our lab. Through this technology, it is found that certain component in Fe-B system has a two-dimensional superconductivity [APL Mater.1,042101 (2013)], which is the first case of successfully employing this technology into the new superconducting material exploration.



For the first time to study the anisotropic electron transport properties of new iron-based high-temperature superconductors (Li,Fe)OHFe0.98Se bulk single crystals, strong two-dimensional electron characteristics are discovered. The comparative study on the previous electron-doped system indicated that the two-dimensional antiferromagnetic fluctuation is closely related to the high-temperature superconductivity [Phys Rev B 92,064515 (2015); JACS 137,66 (2015)]


Patents (submitted/approved)