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
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.
