Research Direction: Manufacturing low dimension Oxide materials by Laser and studying their properties

Research Activities and Major Achievements

1) We have predicted the polarization remained in electron-doped PbTiO3 materials for the first time. The density functional theory (DFT) is used to prove the polar-metal property of the lone pair electron ferroelectric material PbTi0.875Nb0.125O3. The anisotropic screening effect of doping carriers is studied. We also theoretically studied the effect of compressive stress on the polarized metal phase of ferroelectric material BaTiO3 with non-lone pair electrons. It is found that the compressive stress helps to increase the critical doping concentration and the critical temperature of the polarized structure. It has important guiding significance for obtaining experimentally available polarized metal materials. In addition, based on the first-principles calculation of DFT and the research object of HoNiO3, we have theoretically simulated the relationship between Jahn-Teller effect and charge order stability, crystal structure and orbital order. [Phys. Rev. B 96, 035140 (2017), Phys. Rev. B 97, 115103 (2018), Phys. Rev. B 97, 195132 (2018)], In addition, based on the theoretical prediction, we have successfully achieved the electronic doping of the traditional ferroelectric material PbTiO3. Its ferroelectricity and metal conductivity have been artificially designed and regulated, thus giving excellent candidates for a very rare material “ferroelectric metal”. Meanwhile, magnetoresistance and oxygen vacancy-induced ferromagnetism were observed in this polarized metal for the first time, proving the existence of magnetism in ferroelectric metals and proving the coexistence of ferromagnetism, ferroelectricity, and metallicity in this material; also demonstrated the important influence of oxygen vacancies on the structure and physical properties of perovskite oxides. [Nat. Commun. 8, 104 (2017), Phys. Rev. B 96, 165206 (2017), Phys. Rev. B 96, 115105 (2017), ACS Appl. Electr. Mat. 1(7),1225 (2019), Adv. Electron. Mater. 3, 1700321 (2017)]

2) In the field of light interacting with oxide materials, we have demonstrated the coexistence of displacement and ordered-disorder modes in the phase transition of ferroelectric BaTiO3 with pure optical means (second harmonic generation) for the first time, which also has a certain memory of its initial state. We have clarified the linear relationship between the optical SHG polarization anisotropy diagrams and the azimuth/polarization direction of the sample. Through the self-built ultrafast magneto-optical measurement system, we have observed ultrafast demagnetization and magnetic moment spin consistent precession signals of La0.7Sr0.3MnO3 film. We have studied the effects of magnetic field, temperature, optical power, and polarization direction on spin precession behavior. The interaction between light and multi-iron, graphene coating film and pleated crystallites was also explored. Meanwhile, we have researched the spin–orbit coupling interaction of one organic material based on the La0.67Sr0.33MnO3 as electrodes. [Phys. Rev. Lett. 120, 213901 (2018), Adv. Mater. 29, 1702494 (2017), Nanoscale, 9, 15576–15581 (2017), SMALL. 14, 1704429 (2018), Sci. Rep. 7, 9051 (2017), Sci. China. Phys. Mech. 60, 047511 (2017), Appl. Phys. Lett. 112, 102904 (2018), Adv. Electr. Mat. 1900318 (2019)]

3) An electrolyte-gated transistor using WO3 with a unique tunnel structure, which can emulate the ionic modulation process of biological synapses, is proposed. The transistor successfully realizes synaptic functions of both short-term and long-term plasticity by controlling H+ with electrolyte gating. The proposed synaptic electrolyte-gated transistor may be promising for future synaptic electronics. We presented a novel three-terminal ferrite synaptic device based on a topotactic phase transition through electrolyte-gating controlled O2- migration. This three-terminal artificial synapse can mimic important synaptic functions, such as synaptic plasticity and spike-timing-dependent plasticity. These results provide insight into the potential application of advanced topotactic phase transformation materials for designing artificial synapses with high performance. Nonvolatile multilevel conduction states can be realized in the SrCoOx films through controlling the insertion and extraction of oxygen ions with electrolyte gating. The synaptic functions such as the long-term potentiation and depression of synaptic weight, spike-timing-dependent plasticity, as well as spiking logic operations in the device are successfully mimicked.

Projects, funds, staff and students

[1] National Natural Science Foundation of China (Nos. 11721404, 11674385, 11404380, 11874412, 11574219, and 11974390)
[2] National Basic Research Program of China (Nos. 2014CB921001 and 2014CB921003)
[3] National Key R&D Program of China (No.2017YFA0303604)
[4] Strategic Priority Research Program (B) of CAS (No. XDB07030200)
[5] Key Research Program of Frontier Sciences, CAS (No. QYZDJSSW-SLH020)
[6] Youth Innovation Promotion Association, CAS (No. 2018008)
[7] Hundred Talents Program, CAS

We have 10 PHD students and 4 Postdoc.
Number of SCI papers published over the past three years: 40.

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