A Weyl node is characterized by its chirality and tilt.We develop a theory of how nth-order nonlinear optical conductivity behaves under transformations of anisotropic tensor and tilt, which clarifies how chirality-de...A Weyl node is characterized by its chirality and tilt.We develop a theory of how nth-order nonlinear optical conductivity behaves under transformations of anisotropic tensor and tilt, which clarifies how chirality-dependent and-independent parts of optical conductivity transform under the reversal of tilt and chirality.Built on this theory, we propose ferromagnetic Mn Bi2Te4as a magnetoelectrically regulated, terahertz optical device, by magnetoelectrically switching the chiralitydependent and-independent DC photocurrents.These results are useful for creating nonlinear optical devices based on the topological Weyl semimetals.展开更多
In this pedagogically oriented review,we discuss the concept of Berry phase in quantum physics,paying particular attention to their manifestation in Bloch electrons.We have discussed,within the limited scope and passa...In this pedagogically oriented review,we discuss the concept of Berry phase in quantum physics,paying particular attention to their manifestation in Bloch electrons.We have discussed,within the limited scope and passage,a few examples to illustrate the rich and fascinating manifestations of Berry phase in our understanding of many a physical property of a wide range of materials,including optoelectronic responses and quantum transport properties.It is also demonstrated that various topological phases of current interest are characterized by topological numbers,which are in fact incarnations of the Berry phase.A discussion of various techniques for gauge fixing,which may be important to the computation of Berry phase related properties,is also included.展开更多
基金Project supported by the National Key R&D Program of China (Grant Nos.2018YFA, 0305601, and 2021YFA1400100)the National Natural Science Foundation of China (Grant Nos.12274003, 11725415, and 11934001)the Innovation Program for Quantum Science and Technology (Grant No.2021ZD0302600)。
文摘A Weyl node is characterized by its chirality and tilt.We develop a theory of how nth-order nonlinear optical conductivity behaves under transformations of anisotropic tensor and tilt, which clarifies how chirality-dependent and-independent parts of optical conductivity transform under the reversal of tilt and chirality.Built on this theory, we propose ferromagnetic Mn Bi2Te4as a magnetoelectrically regulated, terahertz optical device, by magnetoelectrically switching the chiralitydependent and-independent DC photocurrents.These results are useful for creating nonlinear optical devices based on the topological Weyl semimetals.
基金supported by the National Natural Science Foundation of China(Grant No.11725415)
文摘In this pedagogically oriented review,we discuss the concept of Berry phase in quantum physics,paying particular attention to their manifestation in Bloch electrons.We have discussed,within the limited scope and passage,a few examples to illustrate the rich and fascinating manifestations of Berry phase in our understanding of many a physical property of a wide range of materials,including optoelectronic responses and quantum transport properties.It is also demonstrated that various topological phases of current interest are characterized by topological numbers,which are in fact incarnations of the Berry phase.A discussion of various techniques for gauge fixing,which may be important to the computation of Berry phase related properties,is also included.
