Superconducting copper oxide (Pb_(0.5)Cd_(0.5))Sr_(2)(Lu_(x)Ca_(1-x))Cu_(2)O_(z) has been prepared in oxygen atmosphere.The zero resistivity temperature is 50K for the x=0.5 sample and 43K for the x=0.7 sample.The lat...Superconducting copper oxide (Pb_(0.5)Cd_(0.5))Sr_(2)(Lu_(x)Ca_(1-x))Cu_(2)O_(z) has been prepared in oxygen atmosphere.The zero resistivity temperature is 50K for the x=0.5 sample and 43K for the x=0.7 sample.The lattice constants are a=0.3805nm,c=1.2008nm.Phase and superconductivity are discussed in this paper.展开更多
The magnetic properties of cobalt-based oxypnictides SmCoAsO are investigated by measuring magnetization,magnetoresistance and specific heat.The compound undergoes a ferromagnetic(FM) transition around Tc of 80 K,and ...The magnetic properties of cobalt-based oxypnictides SmCoAsO are investigated by measuring magnetization,magnetoresistance and specific heat.The compound undergoes a ferromagnetic(FM) transition around Tc of 80 K,and a ferromagnetic to antiferromagnetic(AFM) transition below TN1 of about 45 K,and finally an AFM order of Sm ion at TN2 of 5.6 K.The weak FM order should originate from the itinerant 3d electrons of Co ions in the CoAs layers.We propose that the magnetic structure should be A-type AFM,which means that the FM order remains within the CoAs layer and the magnetic coupling between the CoAs layers becomes AFM below TN1 of 45 K.The AFM coupling between the CoAs layers should be very weak.A magnetic field μ0H of about 2 T may cause an AFM-FM metamagnetic transition.A rich magnetic phase diagram is established and the interplay between the 3d electrons of Co ions and 4f electrons of Sm ions is discussed.展开更多
We report the antimony(Sb) doping effect in a prototype system of iron-based superconductors LaFeAsO1-yFy(y=0,0.1,0.15).X-ray powder diffraction indicates that the lattice parameters increase with Sb content within th...We report the antimony(Sb) doping effect in a prototype system of iron-based superconductors LaFeAsO1-yFy(y=0,0.1,0.15).X-ray powder diffraction indicates that the lattice parameters increase with Sb content within the doping limit.Rietveld structural refinements show that,with the partial substitution of Sb for As,the thickness of the Fe2As2 layers increases significantly,whereas that of the La2O2 layers shrinks simultaneously.So a negative chemical pressure is indeed "applied" to the superconducting-active Fe2As2 layers,in contrast to the effect of positive chemical pressure by the phosphorus doping.Electrical resistance and magnetic susceptibility measurements indicate that,while the Sb doping hardly influences the SDW anomaly in LaFeAsO,it recovers SDW order for the optimally-doped sample of y=0.1.In the meantime,the superconducting transition temperature can be raised up to 30 K in LaFeAs1-xSbxO1-yFy with x=0.1 and y=0.15.The Sb doping effects are discussed in term of both J1-J2 model and Fermi Surface(FS) nesting scenario.展开更多
In order to experimentally probe into the complicated interaction between charge ordering and spin ordering in manganites,two sets of samples Nd0.5Sr0.5Mn1-xGaxO3(NSMGO) and Nd 0.5Sr0.5Mn1-y CryO3(NSMCO)(0.0 x,y 0.075...In order to experimentally probe into the complicated interaction between charge ordering and spin ordering in manganites,two sets of samples Nd0.5Sr0.5Mn1-xGaxO3(NSMGO) and Nd 0.5Sr0.5Mn1-y CryO3(NSMCO)(0.0 x,y 0.075),have been studied by means of electrical transport,magnetization,electron spin resonance and transmission electron microscopy analysis.By comparing the influence of Cr-doping and Ga-doping in the Nd0.5Sr0.5MnO3(NSMO) system,large difference between the evolution of charge ordering temperature T co in the Cr-doping and the Ga-doping cases is found.In the NSMCO system,the CE-type antiferromagnetic(AFM)/charge ordering(CO) phase disappears with only 2.5 percent Cr doping;but in the NSMGO system,the CE-type AFM/CO phase always exists.This phenomenon indicates that the charge ordering formation is dominated by the spin ordering.As a result,it is experimentally proved that there is strong coupling interaction between charge ordering and spin ordering in NSMO system.展开更多
文摘Superconducting copper oxide (Pb_(0.5)Cd_(0.5))Sr_(2)(Lu_(x)Ca_(1-x))Cu_(2)O_(z) has been prepared in oxygen atmosphere.The zero resistivity temperature is 50K for the x=0.5 sample and 43K for the x=0.7 sample.The lattice constants are a=0.3805nm,c=1.2008nm.Phase and superconductivity are discussed in this paper.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10931160425 and 10634030)the Natural Science Foundation of Zhejiang Province (Grant No. Y6090564)
文摘The magnetic properties of cobalt-based oxypnictides SmCoAsO are investigated by measuring magnetization,magnetoresistance and specific heat.The compound undergoes a ferromagnetic(FM) transition around Tc of 80 K,and a ferromagnetic to antiferromagnetic(AFM) transition below TN1 of about 45 K,and finally an AFM order of Sm ion at TN2 of 5.6 K.The weak FM order should originate from the itinerant 3d electrons of Co ions in the CoAs layers.We propose that the magnetic structure should be A-type AFM,which means that the FM order remains within the CoAs layer and the magnetic coupling between the CoAs layers becomes AFM below TN1 of 45 K.The AFM coupling between the CoAs layers should be very weak.A magnetic field μ0H of about 2 T may cause an AFM-FM metamagnetic transition.A rich magnetic phase diagram is established and the interplay between the 3d electrons of Co ions and 4f electrons of Sm ions is discussed.
基金supported by the Natural National Science Foundation of China (Grant No. 90922002)the National Basic Research Program of China (Grant No. 2007CB925001)the PCSIRT of the Ministry of Education of China (Grant No. IRT0754)
文摘We report the antimony(Sb) doping effect in a prototype system of iron-based superconductors LaFeAsO1-yFy(y=0,0.1,0.15).X-ray powder diffraction indicates that the lattice parameters increase with Sb content within the doping limit.Rietveld structural refinements show that,with the partial substitution of Sb for As,the thickness of the Fe2As2 layers increases significantly,whereas that of the La2O2 layers shrinks simultaneously.So a negative chemical pressure is indeed "applied" to the superconducting-active Fe2As2 layers,in contrast to the effect of positive chemical pressure by the phosphorus doping.Electrical resistance and magnetic susceptibility measurements indicate that,while the Sb doping hardly influences the SDW anomaly in LaFeAsO,it recovers SDW order for the optimally-doped sample of y=0.1.In the meantime,the superconducting transition temperature can be raised up to 30 K in LaFeAs1-xSbxO1-yFy with x=0.1 and y=0.15.The Sb doping effects are discussed in term of both J1-J2 model and Fermi Surface(FS) nesting scenario.
基金supported by the National Basic Research Program of China(Grant No. 2007CB925001)the National Natural Science Foundation of China (Grant No. 20801050)Zhejiang Provincial Natural Science Foundation (Grant No. Y4080114)
文摘In order to experimentally probe into the complicated interaction between charge ordering and spin ordering in manganites,two sets of samples Nd0.5Sr0.5Mn1-xGaxO3(NSMGO) and Nd 0.5Sr0.5Mn1-y CryO3(NSMCO)(0.0 x,y 0.075),have been studied by means of electrical transport,magnetization,electron spin resonance and transmission electron microscopy analysis.By comparing the influence of Cr-doping and Ga-doping in the Nd0.5Sr0.5MnO3(NSMO) system,large difference between the evolution of charge ordering temperature T co in the Cr-doping and the Ga-doping cases is found.In the NSMCO system,the CE-type antiferromagnetic(AFM)/charge ordering(CO) phase disappears with only 2.5 percent Cr doping;but in the NSMGO system,the CE-type AFM/CO phase always exists.This phenomenon indicates that the charge ordering formation is dominated by the spin ordering.As a result,it is experimentally proved that there is strong coupling interaction between charge ordering and spin ordering in NSMO system.
