简介：AnewlygrownBaGa4Se7crystalhasbeensynthesizedviatheBridgman-Stockbargertechnique.Thisnewcrystalhasadvantagesofhighnonlinearoptics(NLO)coefficients,highlaserdamagethresholds,andwidetransparentregions.TheBaGa4Se7crystalhasbrightapplicationprospectsasanonlineargainmediuminmid-infraredandterahertzregions.Inthispaper,thecrystallinestructureandsyntheticmethodoftheBaGa4Se7crystalareintroduced.Therefractiveindicesandabsorptioncoefficientsalongthreedielectricaxesbetween0.1THzand1.0THzarealsoobtained.Theterahertzdifferencefrequencygeneration(THz-DFG)characteristicsbasedontheBaGa4Se7crystalinthefrequencyrangeof0.1THzto1.0THzareanalyzedtheoreticallyandthephase-matchingconditionsarecalculated.TheapplicationofBaGa4Se7crystalsinterahertzwavegenerationisalsodiscussed.

简介：二轨道的哈伯德模型被在真实空间和动量空间使用Hartree-Fock近似数字地学习，并且碱金属的地面状态性质熨硒化物半导体的KFe1.5Se2被调查。有，顺序被发现的stripetypeantiferromagnetic(AFM)的一份菱形类型Fe空缺订单在散布实验的中子被观察[J.赵，等，Phys。加快。Lett。109，267003(2012)]。跳跃参数被在真实空间适合试验性地观察的条纹AFM阶段获得。这些跳跃参数然后被用来在动量空格学习半导体的地面状态性质。是有大所在地的库仑排斥U的一个强烈相关的系统被发现，类似于莫特·阿夫姆绝缘体铜氧化物超导体的父母混合物。我们也发现在dxz和dyzorbitals的电子职业数字和磁化同时变得不同，显示轨道的订什么时候U>Uc(3.4eV)。这些结果暗示在二orbitals之间的旋转对称被轨道的订打破并且因此驾驶磁性的联合的强壮的anisotropy被实验观察了并且在这混合物的条纹类型AFM顺序可以被和观察大anisotropy的轨道的订引起。

简介：Broadband（1.6–18THz）terahertztime-domainspectroscopy（THz-TDS）andtime-resolvedterahertzspectroscopy（TRTS）wereperformedona54μmthickchalcogenideglass(As30Se30Te40)samplewithatwo-colorlaser-inducedairplasmaTHzsystemintransmissionandreflectionmodes,respectively.Twoabsorptionbandsat2–3and5–8THzwereobserved.TRTSrevealsanultrafastrelaxationprocessofthephotoinducedcarrierresponse,welldescribedbyarateequationmodelwithafiniteconcentrationofmid-bandgaptrapstatesforself-trappedexcitons.ThephotoinducedconductivitycanbewelldescribedbytheDrude–Smithconductivitymodelwithacarrierscatteringtimeof12–17fs,andweobservesignificantcarrierlocalizationeffects.Afastrefractiveindexchangewasobserved100fsbeforetheconductivityreacheditsmaximum,with2ordersofmagnitudelargeramplitudethanexpectedfortheopticallyinducedTHzKerreffect,indicatingthatfreecarriersareresponsibleforthetransientindexchange.

简介：Inthiswork,asimpleandfacileone-potoleylaminesolvothermalsyntheticmethodwasdevelopedtosynthesizeCu_2ZnSnS_4(CZTS)nanocrystals.AndtheCu_2ZnSn(S,Se)_4(CZTSSe)thinfilmswerepreparedbyselenizingCZTSnanocrystals.TheobtainedCZTSnanocrystalsandCZTSSefilmswerestudiedusingX-raydiffraction(XRD),transmissionelectronmicroscopy(TEM),scanningelectronmicroscopy(SEM),energy-dispersiveX-rayspectroscopy(EDX),andultraviolet–visiblespectrophotometer(UV–Vis).TEMresultsshowthatthesphere–likeCZTSnanoparticleswithdiameterbetween12and35nmarepolydispersed.XRDstudiesindicatethatthepreparedCZTSnanocrystalsformkesteritecrystalstructure,andtheCZTSSefilmswithkesteritecrystalstructurearealsoobtainedattheannealingtemperaturesof500and550°C.Inparticularafterannealingat500°Cfor20min,theCZTSSefilmexhibitsasmooth,uniform,crack-free,andlarge-grainedtopographyandpossessesCu-poorandSn-richcomposition.Moreover,itshowsstrongopticalabsorptionfromvisibletonear-infrared(IR)region,anditsopticalbandgap(Eg)isfoundtobeabout1.44eV.