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
Light-emission devices based on In Ga N/Ga N quantum well(QW)bring about an ongoing revolution in general lighting.One of the highly deliberated discussions in this field is the steep efficiency drop with the increasi...Light-emission devices based on In Ga N/Ga N quantum well(QW)bring about an ongoing revolution in general lighting.One of the highly deliberated discussions in this field is the steep efficiency drop with the increasing indium content of In Ga N/Ga N QW,posing a critical challenge to In Ga N-based long-wavelength optoelectronic devices.Unfortunately,the factors that underlie the limitation remain unclear.Here,by using femtosecond transient absorption spectroscopy,we investigate the carrier dynamics of In Ga N/Ga N QW and find that the luminescence efficiency of In Ga N/Ga N QW is closely related to the localization states(LSs),i.e.,dot-like In-rich In Ga N clusters,in the In Ga N layer.We demonstrate that the increase in the indium content can not only decrease the potential depth of LSs to weaken the localization binding effect and enhance the possibility of electrons being trapped by defects,but also enhance the density of LSs to increase the recombination channels and enlarge the full width at half maximum of the luminescence spectra.With these findings,we propose a model of carrier dynamics to deeply understand the emission mechanisms of In Ga N/Ga N QW,paving a way towards realizing highperformance In Ga N-based optoelectronic devices.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.
基金National Natural Science Foundation of China(62027822,U22A20134,62474080,U24A20300)National Key Research and Development Program of China(2021YFB3601002,2022YFB3605205,2024YFB3613900)Jilin Provincial Scientific and Technological Development Program(XXX202402001)。
文摘Light-emission devices based on In Ga N/Ga N quantum well(QW)bring about an ongoing revolution in general lighting.One of the highly deliberated discussions in this field is the steep efficiency drop with the increasing indium content of In Ga N/Ga N QW,posing a critical challenge to In Ga N-based long-wavelength optoelectronic devices.Unfortunately,the factors that underlie the limitation remain unclear.Here,by using femtosecond transient absorption spectroscopy,we investigate the carrier dynamics of In Ga N/Ga N QW and find that the luminescence efficiency of In Ga N/Ga N QW is closely related to the localization states(LSs),i.e.,dot-like In-rich In Ga N clusters,in the In Ga N layer.We demonstrate that the increase in the indium content can not only decrease the potential depth of LSs to weaken the localization binding effect and enhance the possibility of electrons being trapped by defects,but also enhance the density of LSs to increase the recombination channels and enlarge the full width at half maximum of the luminescence spectra.With these findings,we propose a model of carrier dynamics to deeply understand the emission mechanisms of In Ga N/Ga N QW,paving a way towards realizing highperformance In Ga N-based optoelectronic devices.
