一、教学背景(一)教学内容本课堂的教学内容是牛津上海版(深圳用)小学《英语》三年级(下)Module 2 Unit 4 Animals in the Zoo第一课时,是一堂会话课。本单元的会话设计了“动物园嘉年华”的情景,以凯蒂(Kitty)与本(Ben)两人参观动物园...一、教学背景(一)教学内容本课堂的教学内容是牛津上海版(深圳用)小学《英语》三年级(下)Module 2 Unit 4 Animals in the Zoo第一课时,是一堂会话课。本单元的会话设计了“动物园嘉年华”的情景,以凯蒂(Kitty)与本(Ben)两人参观动物园进行对话的形式呈现。让学生在用“I like.../I don’t like...”表达的同时,培养对自然的热爱及保护和关爱动物的意识。展开更多
The measurements on temperature dependences of magnetic susceptibility χ（T）, specific heat C（T）, and electrical resistivity ρ（T） were carried out for the antiferromagnetic（AFM）（Ce（1-x）Lax）2Ir3Ge5（0 ≤ x...The measurements on temperature dependences of magnetic susceptibility χ（T）, specific heat C（T）, and electrical resistivity ρ（T） were carried out for the antiferromagnetic（AFM）（Ce（1-x）Lax）2Ir3Ge5（0 ≤ x ≤ 0.66） system. It was found that the Neel temperature TNdecreases with increasing La content x, and reaches 0 K near a critical content xcr =0.6. A new phase diagram was constructed based on these measurements. A non-Fermi liquid behavior in ρ（T） and a log T relationship in C（T） were found in the samples near xcr, indicating them to be near an AFM quantum critical point（QCP） with strong spin fluctuation. Our finding indicates that（Ce（1-x）Lax）2Ir3Ge5 may be a new platform to search for unconventional superconductivity.展开更多
Unconventional superconductivity,in particular,in noncentrosymmetric systems,has been a long-sought topic in condensed matter physics.Recently,Re-based superconductors have attracted great attention owing to the poten...Unconventional superconductivity,in particular,in noncentrosymmetric systems,has been a long-sought topic in condensed matter physics.Recently,Re-based superconductors have attracted great attention owing to the potential time-reversal symmetry breaking in their superconducting states.We report the superconducting properties of noncentrosymmetric compounds Ta_(x)Re_(1-x) with 0.1 ≤x≤0.25,and find that the superconducting transition temperature reaches a maximum of ~8 K at the optimal level x=0.15.Nevertheless,muon-spin rotation and relaxation measurements reveal no time-reversal symmetry breaking existing in its superconducting state,which is in sharp contrast to both centrosymmetric Re metal and many other noncentrosymmetric Re-based superconductors.展开更多
Compounds with the A15 structure have attracted extensive attention due to their superconductivity and nontrivial topological band structures.We have successfully grown Nb_(3)Sb single crystals with the A15 structure ...Compounds with the A15 structure have attracted extensive attention due to their superconductivity and nontrivial topological band structures.We have successfully grown Nb_(3)Sb single crystals with the A15 structure and systematically measured the longitudinal resistivity,Hall resistivity and quantum oscillations in magnetization.Similar to other topological trivial/nontrivial semimetals,Nb_(3)Sb exhibits large magnetoresistance(MR)at low temperatures(717%,2 K and 9 T),unsaturating quadratic field dependence of MR and up-turn behavior in ρ_(xx)(T)curves under magnetic field,which is considered to result from a perfect hole-electron compensation,as evidenced by the Hall resistivity measurements.The nonzero Berry phase obtained from the de-Hass van Alphen(dHvA)oscillations demonstrates that Nb_(3)Sb is topologically nontrivial.These results indicate that Nb_(3)Sb superconductor is also a semimetal with large MR and nontrivial Berry phase.This indicates that Nb_(3)Sb may be another platform to search for the Majorana zero-energy mode.展开更多
We performed calculations of the electronic band structure and the Fermi surface,measured the longitudinal resistivity ρxx(T,H),Hall resistivity ρxy(T,H),and magnetic susceptibility as a function of temperature at v...We performed calculations of the electronic band structure and the Fermi surface,measured the longitudinal resistivity ρxx(T,H),Hall resistivity ρxy(T,H),and magnetic susceptibility as a function of temperature at various magnetic fields for VAs_(2) with a monoclinic crystal structure.The band structure calculations show that VAs_(2) is a nodal-line semimetal when spin-orbit coupling is ignored.The emergence of a minimum at around11 K in ρxx(T) measured at H=0 demonstrates that some additional magnetic impurities(V^(4+),S=1/2)exist in VAs_(2) single crystals,inducing Kondo scattering,evidenced by both the fitting of ρxx(T) data and the susceptibility measurements.It is found that a large positive magnetoresistance(MR) reaching 649% at 10 K and 9 T,its nearly quadratic field dependence,and a field-induced up-turn behavior of ρxx(T) also emerge in VAs_(2),although MR is not so large due to the existence of additional scattering compared with other topological nontrivial/trivial semimetals.The observed properties are attributed to a perfect charge-carrier compensation,which is evidenced by both the calculations relying on the Fermi surface and the Hall resistivity measurements.These results indicate that the compounds containing V(3d^(3)4s^(2)) element can be as a platform for studying the influence of magnetic impurities to the topological properties.展开更多
The measurements of magnetization,longitudinal and Hall resistivities are carried out on the intrinsic antiferromagnetic(AFM) topological insulator ElSn2 As2.It is confirmed that our ElSn2 As2 crystal is a heavily hol...The measurements of magnetization,longitudinal and Hall resistivities are carried out on the intrinsic antiferromagnetic(AFM) topological insulator ElSn2 As2.It is confirmed that our ElSn2 As2 crystal is a heavily hole doping A-type AFM metal with the Neel temperature TN=24 K,with a metamagnetic transition from an AFM to a ferromagnetic(FIM) phase occurring at a certain critical magnetic Held for the different Held orientations.Meanwhile,we also find that the carrier concentration does not change with the evolution of magnetic order,indicating that the weak interaction between the localized magnetic moments from Eu2+4f7 orbits and the electronic states near the Fermi level.Although the quantum anomalous Hall effect(AHE) is not observed in our crystals,it is found that a relatively large negative magnetoresistance (-13%) emerges in the AFM phase,and exhibits an exponential dependence upon magnetic Held,whose microscopic origin is waiting to be clarified in future research.展开更多
文摘一、教学背景(一)教学内容本课堂的教学内容是牛津上海版(深圳用)小学《英语》三年级(下)Module 2 Unit 4 Animals in the Zoo第一课时,是一堂会话课。本单元的会话设计了“动物园嘉年华”的情景,以凯蒂(Kitty)与本(Ben)两人参观动物园进行对话的形式呈现。让学生在用“I like.../I don’t like...”表达的同时,培养对自然的热爱及保护和关爱动物的意识。
基金supported by the National Basic Research Program of China(Grant Nos.2016FYA0300402,2015CB921004,and 2012CB821404)the National Natural Science Foundation of China(Grant Nos.11374261 and 11204059)
文摘The measurements on temperature dependences of magnetic susceptibility χ（T）, specific heat C（T）, and electrical resistivity ρ（T） were carried out for the antiferromagnetic（AFM）（Ce（1-x）Lax）2Ir3Ge5（0 ≤ x ≤ 0.66） system. It was found that the Neel temperature TNdecreases with increasing La content x, and reaches 0 K near a critical content xcr =0.6. A new phase diagram was constructed based on these measurements. A non-Fermi liquid behavior in ρ（T） and a log T relationship in C（T） were found in the samples near xcr, indicating them to be near an AFM quantum critical point（QCP） with strong spin fluctuation. Our finding indicates that（Ce（1-x）Lax）2Ir3Ge5 may be a new platform to search for unconventional superconductivity.
基金Supported by the National Key R&D Program of China(Grant No.2018YFA0704300)the National Natural Science Foundation of China(Grant Nos.U1732162,11974061,11704047,U1832147 and 11674054)the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB25000000)。
文摘Unconventional superconductivity,in particular,in noncentrosymmetric systems,has been a long-sought topic in condensed matter physics.Recently,Re-based superconductors have attracted great attention owing to the potential time-reversal symmetry breaking in their superconducting states.We report the superconducting properties of noncentrosymmetric compounds Ta_(x)Re_(1-x) with 0.1 ≤x≤0.25,and find that the superconducting transition temperature reaches a maximum of ~8 K at the optimal level x=0.15.Nevertheless,muon-spin rotation and relaxation measurements reveal no time-reversal symmetry breaking existing in its superconducting state,which is in sharp contrast to both centrosymmetric Re metal and many other noncentrosymmetric Re-based superconductors.
基金the National Key R&D Program of China(Grant No.2016YFA0300402)the National Natural Science Foundation of China(Grant Nos.12074335,and 11974095)the Fundamental Research Funds for the Central Universities。
文摘Compounds with the A15 structure have attracted extensive attention due to their superconductivity and nontrivial topological band structures.We have successfully grown Nb_(3)Sb single crystals with the A15 structure and systematically measured the longitudinal resistivity,Hall resistivity and quantum oscillations in magnetization.Similar to other topological trivial/nontrivial semimetals,Nb_(3)Sb exhibits large magnetoresistance(MR)at low temperatures(717%,2 K and 9 T),unsaturating quadratic field dependence of MR and up-turn behavior in ρ_(xx)(T)curves under magnetic field,which is considered to result from a perfect hole-electron compensation,as evidenced by the Hall resistivity measurements.The nonzero Berry phase obtained from the de-Hass van Alphen(dHvA)oscillations demonstrates that Nb_(3)Sb is topologically nontrivial.These results indicate that Nb_(3)Sb superconductor is also a semimetal with large MR and nontrivial Berry phase.This indicates that Nb_(3)Sb may be another platform to search for the Majorana zero-energy mode.
基金Supported by the National Key R&D Program of China(Grant No.2016YFA0300402)the National Natural Science Foundation of China(Grant Nos.12074335 and 11974095)+1 种基金the Zhejiang Natural Science Foundation(Grant No.LY16A040012)the Fundamental Research Funds for the Central Universities。
文摘We performed calculations of the electronic band structure and the Fermi surface,measured the longitudinal resistivity ρxx(T,H),Hall resistivity ρxy(T,H),and magnetic susceptibility as a function of temperature at various magnetic fields for VAs_(2) with a monoclinic crystal structure.The band structure calculations show that VAs_(2) is a nodal-line semimetal when spin-orbit coupling is ignored.The emergence of a minimum at around11 K in ρxx(T) measured at H=0 demonstrates that some additional magnetic impurities(V^(4+),S=1/2)exist in VAs_(2) single crystals,inducing Kondo scattering,evidenced by both the fitting of ρxx(T) data and the susceptibility measurements.It is found that a large positive magnetoresistance(MR) reaching 649% at 10 K and 9 T,its nearly quadratic field dependence,and a field-induced up-turn behavior of ρxx(T) also emerge in VAs_(2),although MR is not so large due to the existence of additional scattering compared with other topological nontrivial/trivial semimetals.The observed properties are attributed to a perfect charge-carrier compensation,which is evidenced by both the calculations relying on the Fermi surface and the Hall resistivity measurements.These results indicate that the compounds containing V(3d^(3)4s^(2)) element can be as a platform for studying the influence of magnetic impurities to the topological properties.
基金Supported by the National Key Research and Development Program of China under Grant No.2016YFA0300402the National Basic Research Program of China under Grant No.2015CB921004+2 种基金the National Natural Science Foundation of China under Grant Nos.11974095 and 11374261the Zhejiang Natural Science Foundation(No.LY16A040012)the Fundamental Research Funds for the Central Universities.
文摘The measurements of magnetization,longitudinal and Hall resistivities are carried out on the intrinsic antiferromagnetic(AFM) topological insulator ElSn2 As2.It is confirmed that our ElSn2 As2 crystal is a heavily hole doping A-type AFM metal with the Neel temperature TN=24 K,with a metamagnetic transition from an AFM to a ferromagnetic(FIM) phase occurring at a certain critical magnetic Held for the different Held orientations.Meanwhile,we also find that the carrier concentration does not change with the evolution of magnetic order,indicating that the weak interaction between the localized magnetic moments from Eu2+4f7 orbits and the electronic states near the Fermi level.Although the quantum anomalous Hall effect(AHE) is not observed in our crystals,it is found that a relatively large negative magnetoresistance (-13%) emerges in the AFM phase,and exhibits an exponential dependence upon magnetic Held,whose microscopic origin is waiting to be clarified in future research.
