Half-semimetals,characterized by their spin-polarized electronic states,hold significant promise for spintronic applications but remain scarce due to stringent electronic and magnetic criteria.Through a combination of...Half-semimetals,characterized by their spin-polarized electronic states,hold significant promise for spintronic applications but remain scarce due to stringent electronic and magnetic criteria.Through a combination of transport measurements and optical spectroscopy,we investigated the intermetallic compound Mn_(4)Al_(11),which features an exceptionally low carrier concentration and undergoes a magnetic phase transition near 68 K.Transport measurements reveal anomalies that deviate from typical metallic behavior at low temperatures.Optical spectroscopy indicates a small,nearly frequency-independent optical conductivity in the far-infrared region,with spectral weight decreasing as the temperature drops from 300 K to 50 K.These behaviors suggest a temperaturedependent carrier density and significant scattering of charge carriers.Combining experimental findings with calculated electronic band structures,we propose that Mn_(4)Al_(11) is a novel half-semimetal candidate exhibiting a ferrimagnetic ground state.展开更多
A highly efficient and re liable topology-dual buck half bridge inverter (DBI) is introduced. The existenc e of discontinuous conduction mode (DCM) operation state requires the bias of in du ctor current for DBI imple...A highly efficient and re liable topology-dual buck half bridge inverter (DBI) is introduced. The existenc e of discontinuous conduction mode (DCM) operation state requires the bias of in du ctor current for DBI implemented with linear controllers like ramp comparison SP WM (RCSPWM) controllers. A novel operation scheme for DBI and a hysteresis curre nt controlled dual buck half bridge inverter (HCDBI) are proposed. The bias curr ent required by RCSPWM DBI is eliminated and conduction losses are dramatically reduced. HCDBI has greatly improved the modulation performance in DCM region for the benefit of its excellent command tracking capability. The operational schem e and control strategy are presented. Power losses of the conventional half brid ge inverter (CHBI) and HCDBI are compared with mathematical computation, and exp erimental verification is also executed. Both calculational and experimental res ults verify that HCDBI has a superior switching performance over CHBI. Its exce llent high frequency operational capacity provides another access to realize high fre quency operation of inverters.展开更多
The electronic structures, magnetic properties, half-metallicity, and mechanical properties of half-Heulser compounds CoCrZ （Z = S, Se, and Te） were investigated using first-principles calculations within generalize...The electronic structures, magnetic properties, half-metallicity, and mechanical properties of half-Heulser compounds CoCrZ （Z = S, Se, and Te） were investigated using first-principles calculations within generalized gradient approximation based on the density function theory. The half-Heusler compounds show half-metallic properties with a half-metallic gap of 0.15 eV for CoCrS, 0.10 eV for CoCrSe, and 0.31 eV for CoCrTe at equilibrium lattice constant, respectively. The total magnetic moments are 3.00/-tB per formula unit, which agrees well with the Slater-Pauling rule. The half-metallicity, elastic constants, bulk modulus, shear modulus, Pough＇s ratio, Frantesvich ratio, Young＇s modulus, Poisson＇s ratio, and Debye temperature at equilibrium lattice constant and versus lattice constants are reported for the first time. The results indicate that the half-Heulser compounds CoCrZ （Z = S, Se, and Te） maintain the perfect half-metallic and mechanical stability within the lattice constants range of 5.18-5.43 A for CoCrS, 5.09-5.61 A for CoCrSe, and 5.17-6.42 A for CoCrTe, respectively.展开更多
设计一种特别的TiCoSb复合靶材,通过调节各元素在复合靶材上所占面积的大小,可以方便地调节薄膜的成分.采用这种靶材,利用直流磁控溅射和快速退火成功制备单一物相的多晶TiCoSb薄膜;采用X射线衍射(X-raydiffraction,XRD)和原子力显微镜(...设计一种特别的TiCoSb复合靶材,通过调节各元素在复合靶材上所占面积的大小,可以方便地调节薄膜的成分.采用这种靶材,利用直流磁控溅射和快速退火成功制备单一物相的多晶TiCoSb薄膜;采用X射线衍射(X-raydiffraction,XRD)和原子力显微镜(atomic force microscopy,AFM)分析TiCoSb薄膜的结构和表面形貌;利用Hall测试仪初步研究薄膜的电学性质.结果表明,所制备的TiCoSb薄膜对石英玻璃衬底具有良好的粘附力,薄膜均匀致密.经600℃,5 min退火的TiCoSb薄膜的结晶质量较好,薄膜的室温电导率为13.7 S/cm.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12274033 and 12488201)the National Key Research and Development Program of China(Grant Nos.2022YFA1403901 and 2024YFA1408700)。
文摘Half-semimetals,characterized by their spin-polarized electronic states,hold significant promise for spintronic applications but remain scarce due to stringent electronic and magnetic criteria.Through a combination of transport measurements and optical spectroscopy,we investigated the intermetallic compound Mn_(4)Al_(11),which features an exceptionally low carrier concentration and undergoes a magnetic phase transition near 68 K.Transport measurements reveal anomalies that deviate from typical metallic behavior at low temperatures.Optical spectroscopy indicates a small,nearly frequency-independent optical conductivity in the far-infrared region,with spectral weight decreasing as the temperature drops from 300 K to 50 K.These behaviors suggest a temperaturedependent carrier density and significant scattering of charge carriers.Combining experimental findings with calculated electronic band structures,we propose that Mn_(4)Al_(11) is a novel half-semimetal candidate exhibiting a ferrimagnetic ground state.
文摘A highly efficient and re liable topology-dual buck half bridge inverter (DBI) is introduced. The existenc e of discontinuous conduction mode (DCM) operation state requires the bias of in du ctor current for DBI implemented with linear controllers like ramp comparison SP WM (RCSPWM) controllers. A novel operation scheme for DBI and a hysteresis curre nt controlled dual buck half bridge inverter (HCDBI) are proposed. The bias curr ent required by RCSPWM DBI is eliminated and conduction losses are dramatically reduced. HCDBI has greatly improved the modulation performance in DCM region for the benefit of its excellent command tracking capability. The operational schem e and control strategy are presented. Power losses of the conventional half brid ge inverter (CHBI) and HCDBI are compared with mathematical computation, and exp erimental verification is also executed. Both calculational and experimental res ults verify that HCDBI has a superior switching performance over CHBI. Its exce llent high frequency operational capacity provides another access to realize high fre quency operation of inverters.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11647133 and 11674113)the Natural Science Foundation of Hubei Province,China(Grant Nos.2017CFB740 and 2014CFB631)+1 种基金the Scientific Research Items Foundation of Hubei Educational Committee,China(Grant Nos.Q20141802,Q20161803,B2016091,and D20171803)Hubei Provincial Collaborative Innovation Center for Optoelectronics,China
文摘The electronic structures, magnetic properties, half-metallicity, and mechanical properties of half-Heulser compounds CoCrZ （Z = S, Se, and Te） were investigated using first-principles calculations within generalized gradient approximation based on the density function theory. The half-Heusler compounds show half-metallic properties with a half-metallic gap of 0.15 eV for CoCrS, 0.10 eV for CoCrSe, and 0.31 eV for CoCrTe at equilibrium lattice constant, respectively. The total magnetic moments are 3.00/-tB per formula unit, which agrees well with the Slater-Pauling rule. The half-metallicity, elastic constants, bulk modulus, shear modulus, Pough＇s ratio, Frantesvich ratio, Young＇s modulus, Poisson＇s ratio, and Debye temperature at equilibrium lattice constant and versus lattice constants are reported for the first time. The results indicate that the half-Heulser compounds CoCrZ （Z = S, Se, and Te） maintain the perfect half-metallic and mechanical stability within the lattice constants range of 5.18-5.43 A for CoCrS, 5.09-5.61 A for CoCrSe, and 5.17-6.42 A for CoCrTe, respectively.
文摘设计一种特别的TiCoSb复合靶材,通过调节各元素在复合靶材上所占面积的大小,可以方便地调节薄膜的成分.采用这种靶材,利用直流磁控溅射和快速退火成功制备单一物相的多晶TiCoSb薄膜;采用X射线衍射(X-raydiffraction,XRD)和原子力显微镜(atomic force microscopy,AFM)分析TiCoSb薄膜的结构和表面形貌;利用Hall测试仪初步研究薄膜的电学性质.结果表明,所制备的TiCoSb薄膜对石英玻璃衬底具有良好的粘附力,薄膜均匀致密.经600℃,5 min退火的TiCoSb薄膜的结晶质量较好,薄膜的室温电导率为13.7 S/cm.
