Interface and surface physics is an important sub-discipline within condensed matter physics in recent decades. Novel concepts like oxide-electronic device are prompted, and their performance and lifetime are highly d...Interface and surface physics is an important sub-discipline within condensed matter physics in recent decades. Novel concepts like oxide-electronic device are prompted, and their performance and lifetime are highly dependent on the flatness and abruptness of the layer surfaces and interfaces. Reflection high-energy electron diffraction （RHEED）, which is extremely sensitive to surface morphology, has proven to be a versatile technique for the growth study of oxide thin films. A differential pumping unit enables an implementation of RHEED to pulsed laser deposition （PLD） systems, ensuring an in situ monitoring of the film growth process in a conventional PLD working oxygen pressure up to 30 Pa. By optimizing the deposition conditions and analyzing the RHEED intensity oscillations, layer-by-layer growth mode can be attained. Thus atomic control of the film surface and unit-cell control of the film thickness become reality. This may lead to an advanced miniaturization in the oxide electronics, and more importantly the discovery of a range of emergent physical properties at the interfaces. Herein we will briefly introduce the principle of high-pressure RHEED and summarize our main results relevant to the effort toward this objective, including the growth and characterization of twinned Laz/3Caj/3MnO3 thin films and ReTiO〉6/2 （Re = La, Nd; ~5 = 0 - 1） AnBnO3n＋2 structures, on YSZ-buffered ＇Silicon on Insulator＇ and LaA103 substrates, respectively, as well as the study of the initial structure and growth dynamics of YBazCu307-6 thin films on SrTiO3 substrate. Presently we have realized in situ monitoring and growth mode control during oxide thin film deposition process.展开更多
We prepared a series of β-FeSe samples with a nominal composition of Fe1.11Se1-xSbx(0≤x≤0.5).The X-ray diffraction,transport and magnetic measurements were performed on these samples to investigate the structure,th...We prepared a series of β-FeSe samples with a nominal composition of Fe1.11Se1-xSbx(0≤x≤0.5).The X-ray diffraction,transport and magnetic measurements were performed on these samples to investigate the structure,the superconducting properties and the normal state transport and magnetic properties.Although the X-ray diffraction data suggested that Sb atoms were not incorporated into the β-FeSe phase,the transport data showed observable changes of superconductivity,normal state resistivity and magnetoresistance.This was represented by the increase in the superconducting transition temperature and the upper critical field.Also,for the samples with a low level of Sb content,a clear decrease of the normal state resistivity and a substantial increase of the residual resistance ratio were observed.Furthermore,the samples showed a significant increase of the normal state magnetoresistance that appeared not to follow the Kohler's rule.The results were discussed in the frame of reduction of excess Fe at interstitial sites of β-FeSe.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.10974229 and 11174342)
文摘Interface and surface physics is an important sub-discipline within condensed matter physics in recent decades. Novel concepts like oxide-electronic device are prompted, and their performance and lifetime are highly dependent on the flatness and abruptness of the layer surfaces and interfaces. Reflection high-energy electron diffraction （RHEED）, which is extremely sensitive to surface morphology, has proven to be a versatile technique for the growth study of oxide thin films. A differential pumping unit enables an implementation of RHEED to pulsed laser deposition （PLD） systems, ensuring an in situ monitoring of the film growth process in a conventional PLD working oxygen pressure up to 30 Pa. By optimizing the deposition conditions and analyzing the RHEED intensity oscillations, layer-by-layer growth mode can be attained. Thus atomic control of the film surface and unit-cell control of the film thickness become reality. This may lead to an advanced miniaturization in the oxide electronics, and more importantly the discovery of a range of emergent physical properties at the interfaces. Herein we will briefly introduce the principle of high-pressure RHEED and summarize our main results relevant to the effort toward this objective, including the growth and characterization of twinned Laz/3Caj/3MnO3 thin films and ReTiO〉6/2 （Re = La, Nd; ~5 = 0 - 1） AnBnO3n＋2 structures, on YSZ-buffered ＇Silicon on Insulator＇ and LaA103 substrates, respectively, as well as the study of the initial structure and growth dynamics of YBazCu307-6 thin films on SrTiO3 substrate. Presently we have realized in situ monitoring and growth mode control during oxide thin film deposition process.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10974243,10911130357 and 50672125) and Ministry of Science and Technology of China
文摘We prepared a series of β-FeSe samples with a nominal composition of Fe1.11Se1-xSbx(0≤x≤0.5).The X-ray diffraction,transport and magnetic measurements were performed on these samples to investigate the structure,the superconducting properties and the normal state transport and magnetic properties.Although the X-ray diffraction data suggested that Sb atoms were not incorporated into the β-FeSe phase,the transport data showed observable changes of superconductivity,normal state resistivity and magnetoresistance.This was represented by the increase in the superconducting transition temperature and the upper critical field.Also,for the samples with a low level of Sb content,a clear decrease of the normal state resistivity and a substantial increase of the residual resistance ratio were observed.Furthermore,the samples showed a significant increase of the normal state magnetoresistance that appeared not to follow the Kohler's rule.The results were discussed in the frame of reduction of excess Fe at interstitial sites of β-FeSe.
