Hall effects have been the central paradigms in modern physics,materials science and practical applications,and have led to many exciting breakthroughs,including the discovery of topological Chern invariants and the r...Hall effects have been the central paradigms in modern physics,materials science and practical applications,and have led to many exciting breakthroughs,including the discovery of topological Chern invariants and the revolution of metrological resistance standard.To date,the Hall effects have mainly focused on a single degree of freedom(Do F),and most of them require the breaking of spatial-inversion and/or time-reversal symmetries.Here we demonstrate a new type of Hall effect,i.e.,layer-valley Hall effect,based on a combined layer-valley Do F characterized by the product of layer and valley indices.The layer-valley Hall effect has a quantum origin arising from the layer-valley contrasting Berry curvature,and can occur in nonmagnetic centrosymmetric crystals with both spatial-inversion and time-reversal symmetries,transcending the symmetry constraints of single Do F Hall effect based on the constituent layer or valley index.Moreover,the layer-valley Hall effect is highly tunable and shows a W-shaped pattern in response to the out-of-plane electric fields.Additionally,we discuss the potential detection approaches and material-specific design principles of layer-valley Hall effect.Our results demonstrate novel Hall physics and open up exotic paradigms for new research direction of layer-valleytronics that exploits the quantum nature of the coupled layer-valley DoF.展开更多
We study （Ga, Mn）As diluted magnetic semiconductors in terms of the Ruderman-Kittel-Kasuya-Yosida quantum spin model in Green＇s function approach. Random distributions of the magnetic atoms are treated by using an ...We study （Ga, Mn）As diluted magnetic semiconductors in terms of the Ruderman-Kittel-Kasuya-Yosida quantum spin model in Green＇s function approach. Random distributions of the magnetic atoms are treated by using an analytical average of magnetic configurations. Average magnetic moments and spin excitation spectra as functions of temperature can be obtained by solving self-consistent equations, and the Curie temperature TC is given explicitly. Tc is proportional to magnetic atomic concentration, and there exists a maximum for Tc as a function of carrier concentration. Applied to （Ga, Mn）As, the theoretical results are consistent with experiment and the experimental TC can be obtained with reasonable parameters. This modelling can also be applied to other diluted magnetic semiconductors.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.61888102 and 12274447)the National Key Research and Development Program of China(Grant Nos.2021YFA1202900 and 2023YFA1407000)+2 种基金the KeyArea Research and Development Program of Guangdong Province,China(Grant No.2020B0101340001)the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2021B0301030002)the Strategic Priority Research Program of Chinese Academy of Sciences(CAS)(Grant No.XDB0470101)。
文摘Hall effects have been the central paradigms in modern physics,materials science and practical applications,and have led to many exciting breakthroughs,including the discovery of topological Chern invariants and the revolution of metrological resistance standard.To date,the Hall effects have mainly focused on a single degree of freedom(Do F),and most of them require the breaking of spatial-inversion and/or time-reversal symmetries.Here we demonstrate a new type of Hall effect,i.e.,layer-valley Hall effect,based on a combined layer-valley Do F characterized by the product of layer and valley indices.The layer-valley Hall effect has a quantum origin arising from the layer-valley contrasting Berry curvature,and can occur in nonmagnetic centrosymmetric crystals with both spatial-inversion and time-reversal symmetries,transcending the symmetry constraints of single Do F Hall effect based on the constituent layer or valley index.Moreover,the layer-valley Hall effect is highly tunable and shows a W-shaped pattern in response to the out-of-plane electric fields.Additionally,we discuss the potential detection approaches and material-specific design principles of layer-valley Hall effect.Our results demonstrate novel Hall physics and open up exotic paradigms for new research direction of layer-valleytronics that exploits the quantum nature of the coupled layer-valley DoF.
基金Project supported by the National Nature Science Foundation of China (Grant Nos 10774180, 90406010 and 6062109)Funds of the Chinese Academy of Sciences for Key Topics in Innovation Engineering (Grant No KJCX2.YW.W09-5)the National Basic Research Program of China (Grant No 2005CB623602)
文摘We study （Ga, Mn）As diluted magnetic semiconductors in terms of the Ruderman-Kittel-Kasuya-Yosida quantum spin model in Green＇s function approach. Random distributions of the magnetic atoms are treated by using an analytical average of magnetic configurations. Average magnetic moments and spin excitation spectra as functions of temperature can be obtained by solving self-consistent equations, and the Curie temperature TC is given explicitly. Tc is proportional to magnetic atomic concentration, and there exists a maximum for Tc as a function of carrier concentration. Applied to （Ga, Mn）As, the theoretical results are consistent with experiment and the experimental TC can be obtained with reasonable parameters. This modelling can also be applied to other diluted magnetic semiconductors.
