The hybridization gap in strained-layer InAs/In_(x)Ga_(1−x) Sb quantum spin Hall insulators(QSHIs)is significantly enhanced compared to binary InAs/GaSb QSHI structures,where the typical indium composition,x,ranges be...The hybridization gap in strained-layer InAs/In_(x)Ga_(1−x) Sb quantum spin Hall insulators(QSHIs)is significantly enhanced compared to binary InAs/GaSb QSHI structures,where the typical indium composition,x,ranges between 0.2 and 0.4.This enhancement prompts a critical question:to what extent can quantum wells(QWs)be strained while still preserving the fundamental QSHI phase?In this study,we demonstrate the controlled molecular beam epitaxial growth of highly strained-layer QWs with an indium composition of x=0.5.These structures possess a substantial compressive strain within the In_(0.5)Ga_(0.5)Sb QW.Detailed crystal structure analyses confirm the exceptional quality of the resulting epitaxial films,indicating coherent lattice structures and the absence of visible dislocations.Transport measurements further reveal that the QSHI phase in InAs/In_(0.5)Ga_(0.5)Sb QWs is robust and protected by time-reversal symmetry.Notably,the edge states in these systems exhibit giant magnetoresistance when subjected to a modest perpendicular magnetic field.This behavior is in agreement with the𝑍2 topological property predicted by the Bernevig–Hughes–Zhang model,confirming the preservation of topologically protected edge transport in the presence of enhanced bulk strain.展开更多
Surface acoustic wave(SAW)is a powerful technique for investigating quantum phases appearing in twodimensional electron systems.The electrons respond to the piezoelectric field of SAW through screening,attenuating its...Surface acoustic wave(SAW)is a powerful technique for investigating quantum phases appearing in twodimensional electron systems.The electrons respond to the piezoelectric field of SAW through screening,attenuating its amplitude,and shifting its velocity,which is described by the relaxation model.In this work,we systematically study this interaction using orders of magnitude lower SAW amplitude than those in previous studies.At high magnetic fields,when electrons form highly correlated states such as the quantum Hall effect,we observe an anomalously large attenuation of SAW,while the acoustic speed remains considerably high,inconsistent with the conventional relaxation model.This anomaly exists only when the SAW power is sufficiently low.展开更多
This article will briefly describe a Majorana platform made of InAs/GaSb(including InAs/(In)GaSb)semiconductor-superconductor heterostructures.A unique advantage of this platform is that the quantum spin Hall edge sta...This article will briefly describe a Majorana platform made of InAs/GaSb(including InAs/(In)GaSb)semiconductor-superconductor heterostructures.A unique advantage of this platform is that the quantum spin Hall edge state realized in inverted InAs/GaSb is a topologically protected spinless single mode,and can be tuned by front-back dual gates.Similar to a number of other platforms the proximity effect of a conventional s-wave superconductor on the helical edge has been proposed to realize Majorana bound state.We will present an introduction to this platform with a focus on the materials and devices aspects and those points that are particularly illustrative.展开更多
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences (Grant Nos.XDB28000000 and XDB0460000)the Quantum Science and Technology-National Science and Technology Major Project (Grant No.2021ZD0302600)the National Key Research and Development Program of China(Grant No.2024YFA1409002)。
文摘The hybridization gap in strained-layer InAs/In_(x)Ga_(1−x) Sb quantum spin Hall insulators(QSHIs)is significantly enhanced compared to binary InAs/GaSb QSHI structures,where the typical indium composition,x,ranges between 0.2 and 0.4.This enhancement prompts a critical question:to what extent can quantum wells(QWs)be strained while still preserving the fundamental QSHI phase?In this study,we demonstrate the controlled molecular beam epitaxial growth of highly strained-layer QWs with an indium composition of x=0.5.These structures possess a substantial compressive strain within the In_(0.5)Ga_(0.5)Sb QW.Detailed crystal structure analyses confirm the exceptional quality of the resulting epitaxial films,indicating coherent lattice structures and the absence of visible dislocations.Transport measurements further reveal that the QSHI phase in InAs/In_(0.5)Ga_(0.5)Sb QWs is robust and protected by time-reversal symmetry.Notably,the edge states in these systems exhibit giant magnetoresistance when subjected to a modest perpendicular magnetic field.This behavior is in agreement with the𝑍2 topological property predicted by the Bernevig–Hughes–Zhang model,confirming the preservation of topologically protected edge transport in the presence of enhanced bulk strain.
基金supported by the National Key Research and Development Program of China(Grant Nos.2021YFA1401900 and 2019YFA0308403)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB33030000)+1 种基金the National Natural Science Foundation of China(Grant Nos.92065104,12074010,and 12141001)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302602)for sample fabrication and measurement。
文摘Surface acoustic wave(SAW)is a powerful technique for investigating quantum phases appearing in twodimensional electron systems.The electrons respond to the piezoelectric field of SAW through screening,attenuating its amplitude,and shifting its velocity,which is described by the relaxation model.In this work,we systematically study this interaction using orders of magnitude lower SAW amplitude than those in previous studies.At high magnetic fields,when electrons form highly correlated states such as the quantum Hall effect,we observe an anomalously large attenuation of SAW,while the acoustic speed remains considerably high,inconsistent with the conventional relaxation model.This anomaly exists only when the SAW power is sufficiently low.
基金supported by the National Key Research and Development Program of China(Grant No.2019YFA0308400)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB28000000)。
文摘This article will briefly describe a Majorana platform made of InAs/GaSb(including InAs/(In)GaSb)semiconductor-superconductor heterostructures.A unique advantage of this platform is that the quantum spin Hall edge state realized in inverted InAs/GaSb is a topologically protected spinless single mode,and can be tuned by front-back dual gates.Similar to a number of other platforms the proximity effect of a conventional s-wave superconductor on the helical edge has been proposed to realize Majorana bound state.We will present an introduction to this platform with a focus on the materials and devices aspects and those points that are particularly illustrative.
