Complex oxide heterointerfaces can host a rich of emergent phenomena,and epitaxial growth is usually at the heart of forming these interfaces.Recently,a strong crystalline-orientation-dependent two-dimensional superco...Complex oxide heterointerfaces can host a rich of emergent phenomena,and epitaxial growth is usually at the heart of forming these interfaces.Recently,a strong crystalline-orientation-dependent two-dimensional superconductivity was discovered at interfaces between KTaO_(3)single-crystal substrates and films of other oxides.Unexpectedly,rare of these oxide films was epitaxially grown.Here,we report the existence of superconductivity in epitaxially grown LaVO_(3)/KTaO_(3)(111)heterostructures,with a superconducting transition temperature of~0.5 K.Meanwhile,no superconductivity was detected in the(001)-and(110)-orientated LaVO_(3)/KTaO_(3)heterostructures down to 50 mK.Moreover,we find that for the LaVO_(3)/KTaO_(3)(111)interfaces to be conducting,an oxygen-deficient growth environment and a minimum LaVO_(3)thickness of~0.8 nm(~2 unit cells)are needed.展开更多
Thermal-annealing has been widely used in modulating the oxygen content of manganites. In this work, we have studied the effect of annealing on the transport properties and magnetoresistance of junctions composed of a...Thermal-annealing has been widely used in modulating the oxygen content of manganites. In this work, we have studied the effect of annealing on the transport properties and magnetoresistance of junctions composed of a La0.9Ca0.1MnO3＋6 film and a Nb-doped SrTiO3 substrate. We have demonstrated that the magnetoresistance of junctions is strongly dependent on the annealing conditions： Prom the junction annealed-in-air to the junction annealedin-vacuum, the magnetoresistance near 0-V bias can vary from ～-60% to N～0. A possible mechanism accounting for this phenomenon is discussed.展开更多
A junction composed of ultrathin La0.9Ca0.1MnO3＋δ （LCMO） film and 1 wt.% Nb-doped SrTiO3 was fabricated and its magnetoresistance （MR） was studied and compared with LCMO film. It was found that the resistance of...A junction composed of ultrathin La0.9Ca0.1MnO3＋δ （LCMO） film and 1 wt.% Nb-doped SrTiO3 was fabricated and its magnetoresistance （MR） was studied and compared with LCMO film. It was found that the resistance of the junction has a similar dependence on magnetic field as that of the LCMO film： the curvature of R-H curves is upward above Curie temperature （Tc） and downward below TC. These behaviours strongly suggest that the rotation of ferromagnetic clusters in manganite also causes MR in the corresponding junction. This MR can be qualitatively understood by the change of the width of the barrier induced by the rotation of ferromagnetic clusters. These results suggest a possibility to obtain junctions with large low-field MR.展开更多
Interracial barrier is a key factor that determines the performances of heterojunctions. In this work, we study the effect of manganite film thickness on the effective interracial barrier for La0.67Sr0.33MnO3/Nb：SrTi...Interracial barrier is a key factor that determines the performances of heterojunctions. In this work, we study the effect of manganite film thickness on the effective interracial barrier for La0.67Sr0.33MnO3/Nb：SrTiO3 junctions, The barrier is extracted from the forward current-voltage characteristics. Our results demonstrate that the barrier decreases gradually from -0.85 eV to -0.60 eV when the film thickness decreases from 150 nm to 2 nm. The overall value of the barrier is only about 50% of the corresponding one determined from the photovoltaic effect.展开更多
Recently, the quasi-two-dimensional electron gas （q2DEG） confined at the interface between LaAlO3 and SrTiO3 has attracted significant attention. In this paper, we briefly review experimental methods that have been ...Recently, the quasi-two-dimensional electron gas （q2DEG） confined at the interface between LaAlO3 and SrTiO3 has attracted significant attention. In this paper, we briefly review experimental methods that have been used to tune the carrier density and mobility of this q2DEG. These methods can be classified into two categories： growth-related tuning （i.e. substrate, growth temperature, oxygen pressure, post-annealing, LaAlO3 thickness, stoichiometry, and capping layers） and post-growth tuning （i.e. electrostatic field gating, conductive atomic force microscopy and surface adsorbates）. Taken together, these methods enable the broad tuning of the electronic properties of this interface.展开更多
The effect of high pressure on the microstructure of annealed amorphous Nd9Fe85B6 alloy was studied. It was found that application of high pressure made the microstructure of the crystallized alloy much more homogeneo...The effect of high pressure on the microstructure of annealed amorphous Nd9Fe85B6 alloy was studied. It was found that application of high pressure made the microstructure of the crystallized alloy much more homogeneous. The average grain size of the Nd2Fe14B phase decreased with the increase of pressure, whereas, the size of the α-Fe first increased when a pressure of 1 GPa was applied and then decreased with further increase of pressure. Pressure-induced （410） texture of the Nd2Fe14B phase was also observed. The present study suggested an effective route for controlling the microstructure in a nanoscale solid.展开更多
In this study, we have explored the ways to fabricate and optimize high-quality ultrathin YBa2 Cu3 O7-δ(YBCO) films grown on single-crystal(001) SrTiO3 substrates. Nearly atomic-flat YBCO films are obtained by pulsed...In this study, we have explored the ways to fabricate and optimize high-quality ultrathin YBa2 Cu3 O7-δ(YBCO) films grown on single-crystal(001) SrTiO3 substrates. Nearly atomic-flat YBCO films are obtained by pulsed laser deposition.Our result shows that the termination of SrTiO3 has only a negligible effect on the properties of YBCO. In contrast, we found that capping a non-superconducting oxide layer can generally enhance the superconductivity of YBCO. PrBa2 Cu3 O7,La2 CuO4, LaMnO3, SrTiO3, and LaAlO3 have been examined as capping layers, and the minimum thickness of superconducting YBCO with capping is ~ 2 unit cells–3 unit cells. This result might be useful in constructing good-performance YBCO-based field effect devices.展开更多
基金the National Natural Science Foundation of China(Grant Nos.11934016 and 12074334)the Key R&D Program of Zhejiang Province,China(Grant Nos.2020C01019 and 2021C01002)the Fundamental Research Funds for the Central Universities of China.
文摘Complex oxide heterointerfaces can host a rich of emergent phenomena,and epitaxial growth is usually at the heart of forming these interfaces.Recently,a strong crystalline-orientation-dependent two-dimensional superconductivity was discovered at interfaces between KTaO_(3)single-crystal substrates and films of other oxides.Unexpectedly,rare of these oxide films was epitaxially grown.Here,we report the existence of superconductivity in epitaxially grown LaVO_(3)/KTaO_(3)(111)heterostructures,with a superconducting transition temperature of~0.5 K.Meanwhile,no superconductivity was detected in the(001)-and(110)-orientated LaVO_(3)/KTaO_(3)heterostructures down to 50 mK.Moreover,we find that for the LaVO_(3)/KTaO_(3)(111)interfaces to be conducting,an oxygen-deficient growth environment and a minimum LaVO_(3)thickness of~0.8 nm(~2 unit cells)are needed.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10474133 and 10674169)the National Fundamental Research of China (Grant No 2007CB925002)
文摘Thermal-annealing has been widely used in modulating the oxygen content of manganites. In this work, we have studied the effect of annealing on the transport properties and magnetoresistance of junctions composed of a La0.9Ca0.1MnO3＋6 film and a Nb-doped SrTiO3 substrate. We have demonstrated that the magnetoresistance of junctions is strongly dependent on the annealing conditions： Prom the junction annealed-in-air to the junction annealedin-vacuum, the magnetoresistance near 0-V bias can vary from ～-60% to N～0. A possible mechanism accounting for this phenomenon is discussed.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10474133 and 10674169）.
文摘A junction composed of ultrathin La0.9Ca0.1MnO3＋δ （LCMO） film and 1 wt.% Nb-doped SrTiO3 was fabricated and its magnetoresistance （MR） was studied and compared with LCMO film. It was found that the resistance of the junction has a similar dependence on magnetic field as that of the LCMO film： the curvature of R-H curves is upward above Curie temperature （Tc） and downward below TC. These behaviours strongly suggest that the rotation of ferromagnetic clusters in manganite also causes MR in the corresponding junction. This MR can be qualitatively understood by the change of the width of the barrier induced by the rotation of ferromagnetic clusters. These results suggest a possibility to obtain junctions with large low-field MR.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10804094,50832007,50721001 and 50821001)the Natural Science Foundation of Hebei Province,China (Grant No. A2009000339)
文摘Interracial barrier is a key factor that determines the performances of heterojunctions. In this work, we study the effect of manganite film thickness on the effective interracial barrier for La0.67Sr0.33MnO3/Nb：SrTiO3 junctions, The barrier is extracted from the forward current-voltage characteristics. Our results demonstrate that the barrier decreases gradually from -0.85 eV to -0.60 eV when the film thickness decreases from 150 nm to 2 nm. The overall value of the barrier is only about 50% of the corresponding one determined from the photovoltaic effect.
基金Project supported by the Department of Energy,Office of Basic Energy Sciences(Grant No.DE-AC02-76SF00515)
文摘Recently, the quasi-two-dimensional electron gas （q2DEG） confined at the interface between LaAlO3 and SrTiO3 has attracted significant attention. In this paper, we briefly review experimental methods that have been used to tune the carrier density and mobility of this q2DEG. These methods can be classified into two categories： growth-related tuning （i.e. substrate, growth temperature, oxygen pressure, post-annealing, LaAlO3 thickness, stoichiometry, and capping layers） and post-growth tuning （i.e. electrostatic field gating, conductive atomic force microscopy and surface adsorbates）. Taken together, these methods enable the broad tuning of the electronic properties of this interface.
基金the National Natural Science Foundation of China (50671090 and 50525102)the National Basic Research Program (2005CB724404)+1 种基金the Program for New Century Excellent Talents in University (04-0251)the Program for Changjiang Scholars and In-novative Research Team in University ( IRT0650)
文摘The effect of high pressure on the microstructure of annealed amorphous Nd9Fe85B6 alloy was studied. It was found that application of high pressure made the microstructure of the crystallized alloy much more homogeneous. The average grain size of the Nd2Fe14B phase decreased with the increase of pressure, whereas, the size of the α-Fe first increased when a pressure of 1 GPa was applied and then decreased with further increase of pressure. Pressure-induced （410） texture of the Nd2Fe14B phase was also observed. The present study suggested an effective route for controlling the microstructure in a nanoscale solid.
基金Project supported by the National Key Research and Development Program of the Ministry of Science and Technology of China(Grants Nos.2017YFA0303002and 2016YFA0300204)the Fundamental Research Funds for the Central Universities,China
文摘In this study, we have explored the ways to fabricate and optimize high-quality ultrathin YBa2 Cu3 O7-δ(YBCO) films grown on single-crystal(001) SrTiO3 substrates. Nearly atomic-flat YBCO films are obtained by pulsed laser deposition.Our result shows that the termination of SrTiO3 has only a negligible effect on the properties of YBCO. In contrast, we found that capping a non-superconducting oxide layer can generally enhance the superconductivity of YBCO. PrBa2 Cu3 O7,La2 CuO4, LaMnO3, SrTiO3, and LaAlO3 have been examined as capping layers, and the minimum thickness of superconducting YBCO with capping is ~ 2 unit cells–3 unit cells. This result might be useful in constructing good-performance YBCO-based field effect devices.
