A new method of nanocontact fabrication for Adreev reflection measurement based on the nanopore method using a SiN membrane with focused ion beam technique is presented. With this method, controllable, clean,tensionle...A new method of nanocontact fabrication for Adreev reflection measurement based on the nanopore method using a SiN membrane with focused ion beam technique is presented. With this method, controllable, clean,tensionless nano-contacts for spin polarization probing can be obtained. Measurements of the fabricated samples show complicated spectral structures with a zero bias anomaly and dip structures from quasipartical interactions. A control sample of Co40Fe40B20 is measured with Nb tip method. None of the measured spectra can be explained satisfactorily by present theory. Further analysis of the contact interface and a more complete theory are needed to extract a reliable spin polarization message with the point contact Andreev reflection method.展开更多
Andreev reflection （AR） in a normal-metal/quantum-dot/superconductor （N-QD-S） system with coupled Majorana bound states （MBSs） is investigated theoretically. We find that in the N--QD-S system, the AR can be enh...Andreev reflection （AR） in a normal-metal/quantum-dot/superconductor （N-QD-S） system with coupled Majorana bound states （MBSs） is investigated theoretically. We find that in the N--QD-S system, the AR can be enhanced when coupling to the MBSs is incorporated. Fano line-shapes can be observed in the AR conductance spectrum when there is an appropriate QD-MBS coupling or MBS-MBS coupling. The AR conductance is always e2/2h at the zero Fermi energy point when only QD--MBSs coupling is considered. In addition, the resonant AR occurs when the MBS-MBS coupling roughly equals to the QD energy level. We also find that an AR antiresonance appears when the QD energy level approximately equals to the sum of the QD-MBS coupling and the MBS-MBS coupling. These features may serve as characteristic signatures for the probe of MBSs.展开更多
We propose a four-terminal device consisting of two parallel quantum dots with Rashba spin-orbit interaction （RSOI）, coupled to two side superconductor leads and two common ferromagnetic leads, respectively. The two...We propose a four-terminal device consisting of two parallel quantum dots with Rashba spin-orbit interaction （RSOI）, coupled to two side superconductor leads and two common ferromagnetic leads, respectively. The two ferromagnetic leads and two quantum dots form a ring threaded by Aharonov-Bohm （AB） flux. This device possesses normal quasiparticle transmission between the two ferromagnetic leads, and normal and crossed Andreev reflections providing conductive holes. For the appropriate spin polarization of the ferromagnetic leads, RSOI and AB flux, the pure spin-up （or spin-down） current without net charge current in the right lead, which is due to the equal numbers of electrons and holes with the same spin-polarization moving along the same direction, can be obtained by adjusting the gate voltage, which may be used in practice as a pure spin-current injector.展开更多
In this work,we discuss the origin of several anomalies present in the point-contact Andreev reflection spectra of（Li1-xFex）OHFeSe,LiTi2O4,and La2-xCexCuO4.While these features are similar to those stemming from int...In this work,we discuss the origin of several anomalies present in the point-contact Andreev reflection spectra of（Li1-xFex）OHFeSe,LiTi2O4,and La2-xCexCuO4.While these features are similar to those stemming from intrinsic superconducting properties,such as Andreev reflection,electron-boson coupling,multigap superconductivity,d-wave and p-wave pairing symmetry,they cannot be accounted for by the modified Blonder–Tinkham–Klapwijk（BTK） model,but require to consider critical current effects arising from the junction geometry.Our results point to the importance of tracking the evolution of the dips and peaks in the differential conductance as a function of the bias voltage,in order to correctly deduce the properties of the superconducting state.展开更多
We report a systematic investigation on c-axis point-contact Andreev reflection （PCAR） in BaFe2-xNixAs2 superconducting single crystals from underdoped to overdoped regions （0.075≤ x ≤0.15）. At low temperatures,...We report a systematic investigation on c-axis point-contact Andreev reflection （PCAR） in BaFe2-xNixAs2 superconducting single crystals from underdoped to overdoped regions （0.075≤ x ≤0.15）. At low temperatures, an in-gap sharp peak at low-bias voltage is observed in PCAR for overdoped samples, in contrast to the case of underdoped junctions, in which an in-gap plateau is observed. The variety of the conductance spectra with doping can be well described by using a generalized Blonder-Tinkham-Klapwijk formalism with an angle-dependent gap. This gap shows a clear crossover from a nodeless in the underdoped side to a nodal feature in the overdoped region. This result provides evidence of the doping-induced evolution of the superconducting order parameter when the inter-pocket and intra-pocket scattering are tuned through doping, as expected in the s± scenario.展开更多
We theoretically studied the nonlocal Andreev reflection with Rashba spin-orbital interaction in a triple-quantumdot （QD） ring, which is introduced as Rashba spin-orbital interaction to act locally on one component ...We theoretically studied the nonlocal Andreev reflection with Rashba spin-orbital interaction in a triple-quantumdot （QD） ring, which is introduced as Rashba spin-orbital interaction to act locally on one component quantum dot. It is found that the electronic current and spin current are sensitive to the systematic parameters. The interdot spin-flip term does not play a leading role in causing electronic and spin currents. Otherwise the spin precessing terra leads to shift of the peaks of the the spin-up and spin-down electronic currents in different directions and results in the spin current. Moreover, the spin-orbital interaction suppresses the nonlocal Andreev reflection, so we cannot obtain the pure spin current.展开更多
We study spectroscopic signatures of a monochromatic boson mode interacting with a T-shape double quantum dot coupled between the metallic and superconducting leads. Focusing on a weak interdot coupling, we find that ...We study spectroscopic signatures of a monochromatic boson mode interacting with a T-shape double quantum dot coupled between the metallic and superconducting leads. Focusing on a weak interdot coupling, we find that the proximity effect together with the bosonic mode are responsible for the series of Fano-type resonances appearing simultaneously at negative and positive energies. We investigate these interferometric features and discuss their influence on the subgap Andreev conductance taking into account the correlation effects driven by the Coulomb repulsion.展开更多
This paper theoretically reports the nonlocal Andreev reflection and spin current in a normal metal-ferromagnetic metal-superconducting Aharonov-Bohm interferometer. It is found that the electronic current and spin cu...This paper theoretically reports the nonlocal Andreev reflection and spin current in a normal metal-ferromagnetic metal-superconducting Aharonov-Bohm interferometer. It is found that the electronic current and spin current are sensitive to systematic parameters, such as the gate voltage of quantum dots and the external magnetic flux. The electronic current in the normal metal lead results from two competing processes： quasiparticle transmission and nonlocal Andreev reflection. The appearance of zero spin-up electronic current （or spin-down electronic current） signals the existence of nonlocal Andreev reflection, and the presence of zero electronic current results in the appearance of pure spin current.展开更多
When two three-dimensional topological insulators （TIs） are brought close to each other with their surfaces aligned, the surfaces form a line junction. Similarly, three TI surfaces, not lying in a single plane, can ...When two three-dimensional topological insulators （TIs） are brought close to each other with their surfaces aligned, the surfaces form a line junction. Similarly, three TI surfaces, not lying in a single plane, can form an atomic-scale nanostep junction. In this paper, Andreev reflection in a TI-TI-superconductor nanostep junction is investigated theoretically. Be- cause of the existence of edge states along each line junction, the conductance for a nanostep junction is suppressed. When the incident energy （e） of an electron is larger than the superconductor gap （A）, the Andreev conductance in a step junction is less than unity while for a plane junction it is unity. The Andreev conductance is found to depend on the height of the step junction. The Andreev conductance exhibits oscillatory behavior as a function of the junction height with the amplitude of the oscillations remaining unchanged when e = 0, but decreasing for e = A, which is different from the case of the plane junction. The height of the step is therefore an important parameter for Andreev reflection in nanostep junctions, and plays a role similar to that of the delta potential barrier in normal metal-superconductor plane junctions.展开更多
We study Andreev tunneling through a ferromagnet/quantum-dot (QD)/superconductor system. By usingnonequilibrum Green function method, the averaged occupation of electrons in QD and the Andreev tunneling currentare stu...We study Andreev tunneling through a ferromagnet/quantum-dot (QD)/superconductor system. By usingnonequilibrum Green function method, the averaged occupation of electrons in QD and the Andreev tunneling currentare studied. Comparing to the norma-metal/quantum-dot/superconductor, the system shows significant changes: (i)The averaged occupations of spin-up and spin-down electrons are not equal. (ii) With the increase of the polarizationof ferromagnetic lead, the Andreev reflection current decreases. (iii) However, even the ferromagnetic lead reaches fullpolarization, the averaged occupation of spin-down electrons is not zero. The physics of these changes is discussed.展开更多
We investigate the effect of intra-dot Coulomb interaction on the Andreev reflection in a normalmetal/quantum-dot/superconductor (N-QD-S) system with multiple levels in the quantum dot, in the regime where the intra-d...We investigate the effect of intra-dot Coulomb interaction on the Andreev reflection in a normalmetal/quantum-dot/superconductor (N-QD-S) system with multiple levels in the quantum dot, in the regime where the intra-dot interacting constant is comparable to the energy gap of superconducting lead. By using nonequilibrium Green function method, the averaged occupation of electrons in the quantum dot and the Andreev reflection (AR) current are studied. Comparing to the case of non-interacting quantum dot, the system shows significant changes for the a two-step-like behavior; and the I-Vg shows two groups of peaks, separated by U and with equal heights, where Vg is the gate voltage and U denotes the intra-dot Coulomb interaction constant. (ii) For finite bias voltage, dips, superposed V ≥ U/2, extra AR current peaks occur between the two groups of the peaks. Besides, the properties of the heights of the AR current peaks are more complicated.展开更多
We study Andreev tunneling through a ferromagnet/quantum-dot (QD)/superconductor system. By usingnonequilibrum Green function method, the averaged occupation of electrons in QD and the Andreev tunneling currentare stu...We study Andreev tunneling through a ferromagnet/quantum-dot (QD)/superconductor system. By usingnonequilibrum Green function method, the averaged occupation of electrons in QD and the Andreev tunneling currentare studied. Comparing to the norma-metal/quantum-dot/superconductor, the system shows significant changes: (i)The averaged occupations of spin-up and spin-down electrons are not equal. (ii) With the increase of the polarizationof ferromagnetic lead, the Andreev reflection current decreases. (iii) However, even the ferromagnetic lead reaches fullpolarization, the averaged occupation of spin-down electrons is not zero. The physics of these changes is discussed.展开更多
The Ising spin–orbit coupling could give rise to the spin-triplet Cooper pairs and equal-spin Andreev reflection(AR)in Ising superconductors.Here we theoretically study the valley-dependent equal-spin AR in a ferroma...The Ising spin–orbit coupling could give rise to the spin-triplet Cooper pairs and equal-spin Andreev reflection(AR)in Ising superconductors.Here we theoretically study the valley-dependent equal-spin AR in a ferromagnet/Ising superconductor junction with a circularly polarized light applied to the ferromagnet.Because of the spin-triplet Cooper pairs and the optical irradiation,eight kinds of AR processes appear in the junction,including equal-spin AR and normal AR,the strengths and properties of which strongly depend on the valley degree of freedom.The AR probabilities for the incident electron from the two valleys exhibit certain symmetry with respect to the magnetization angle and the effective energy of light.The equal-spin AR and normal AR present different features and resonant behaviors near the superconducting gap edges.Due to equal-spin-triplet Cooper pairs,not only charge supercurrent but also spin supercurrent can transport in the Ising superconductors.The differential spin conductance for electron injecting from the two valleys can be controlled by the circularly polarized light.展开更多
We investigate the Andreev reflection across a uniaxial strained graphene-based superconducting junction.Compared with pristine graphene-based superconducting junction,three opposite properties are found.Firstly,in th...We investigate the Andreev reflection across a uniaxial strained graphene-based superconducting junction.Compared with pristine graphene-based superconducting junction,three opposite properties are found.Firstly,in the regime of the interband conversion of electron–hole,the Andreev retro-reflection happens.Secondly,in the regime of the intraband conversion of electron–hole,the specular Andreev reflection happens.Thirdly,the perfect Andreev reflection,electron–hole conversion with unit efficiency,happens at a nonzero incident angle of electron.These three exotic properties arise from the strain-induced anisotropic band structure of graphene,which breaks up the original relation between the direction of velocity of particle and the direction of the corresponding wavevector.Our finding gives an insight into the understanding of Andreev reflection and provides an alternative method to modulate the Andreev reflection.展开更多
文摘A new method of nanocontact fabrication for Adreev reflection measurement based on the nanopore method using a SiN membrane with focused ion beam technique is presented. With this method, controllable, clean,tensionless nano-contacts for spin polarization probing can be obtained. Measurements of the fabricated samples show complicated spectral structures with a zero bias anomaly and dip structures from quasipartical interactions. A control sample of Co40Fe40B20 is measured with Nb tip method. None of the measured spectra can be explained satisfactorily by present theory. Further analysis of the contact interface and a more complete theory are needed to extract a reliable spin polarization message with the point contact Andreev reflection method.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61176089 and 10974043)the Natural Science Foundation of Hebei Province,China(Grant Nos.A2011205092 and 2014205005)the Fund for Hebei Normal University for Nationalities,China(Grant No.201109)
文摘Andreev reflection （AR） in a normal-metal/quantum-dot/superconductor （N-QD-S） system with coupled Majorana bound states （MBSs） is investigated theoretically. We find that in the N--QD-S system, the AR can be enhanced when coupling to the MBSs is incorporated. Fano line-shapes can be observed in the AR conductance spectrum when there is an appropriate QD-MBS coupling or MBS-MBS coupling. The AR conductance is always e2/2h at the zero Fermi energy point when only QD--MBSs coupling is considered. In addition, the resonant AR occurs when the MBS-MBS coupling roughly equals to the QD energy level. We also find that an AR antiresonance appears when the QD energy level approximately equals to the sum of the QD-MBS coupling and the MBS-MBS coupling. These features may serve as characteristic signatures for the probe of MBSs.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10775091,10774094,10974124,and 11047172)the Excellent Youth and Midlife Scientist Scientific Research Encouragement Foundation of Shandong Province,China(Grant No. BS2010DS006)the Doctor Research Startup Foundation of Linyi University,China (Grant No. BS201023)
文摘We propose a four-terminal device consisting of two parallel quantum dots with Rashba spin-orbit interaction （RSOI）, coupled to two side superconductor leads and two common ferromagnetic leads, respectively. The two ferromagnetic leads and two quantum dots form a ring threaded by Aharonov-Bohm （AB） flux. This device possesses normal quasiparticle transmission between the two ferromagnetic leads, and normal and crossed Andreev reflections providing conductive holes. For the appropriate spin polarization of the ferromagnetic leads, RSOI and AB flux, the pure spin-up （or spin-down） current without net charge current in the right lead, which is due to the equal numbers of electrons and holes with the same spin-polarization moving along the same direction, can be obtained by adjusting the gate voltage, which may be used in practice as a pure spin-current injector.
基金Project supported by the National Key Basic Research Program of China(Grant Nos.2015CB921000,2016YFA0300301,and 2017YFA0302902)the National Natural Science Foundation of China(Grant Nos.11674374 and 1474338)+5 种基金the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(Grant No.QYZDB-SSW-SLH008)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDB07020100 and XDB07030200)the Beijing Municipal Science and Technology Project(Grant No.Z161100002116011)the Fonds de la Recherche Scientifique–FNRS and the ARC Grant 13/18-08 for Concerted Research Actions,financed by the French Community of Belgium(Wallonia-Brussels Federation)Jérémy Brisbois acknowledges the support from F.R.S.–FNRS(Research Fellowship)The work of Alejandro V Silhanek is partially supported by PDR T.0106.16 of the F.R.S.–FNRS
文摘In this work,we discuss the origin of several anomalies present in the point-contact Andreev reflection spectra of（Li1-xFex）OHFeSe,LiTi2O4,and La2-xCexCuO4.While these features are similar to those stemming from intrinsic superconducting properties,such as Andreev reflection,electron-boson coupling,multigap superconductivity,d-wave and p-wave pairing symmetry,they cannot be accounted for by the modified Blonder–Tinkham–Klapwijk（BTK） model,but require to consider critical current effects arising from the junction geometry.Our results point to the importance of tracking the evolution of the dips and peaks in the differential conductance as a function of the bias voltage,in order to correctly deduce the properties of the superconducting state.
基金Supported by the National Basic Research Program of China under Grant Nos 2011CBA00100 and 2012CB821404the Project of International Team on Superconductivity and Novel Electronic Materials of Chinese Academy of Sciences
文摘We report a systematic investigation on c-axis point-contact Andreev reflection （PCAR） in BaFe2-xNixAs2 superconducting single crystals from underdoped to overdoped regions （0.075≤ x ≤0.15）. At low temperatures, an in-gap sharp peak at low-bias voltage is observed in PCAR for overdoped samples, in contrast to the case of underdoped junctions, in which an in-gap plateau is observed. The variety of the conductance spectra with doping can be well described by using a generalized Blonder-Tinkham-Klapwijk formalism with an angle-dependent gap. This gap shows a clear crossover from a nodeless in the underdoped side to a nodal feature in the overdoped region. This result provides evidence of the doping-induced evolution of the superconducting order parameter when the inter-pocket and intra-pocket scattering are tuned through doping, as expected in the s± scenario.
基金Project supported by the Natural Science Foundation of Education Bureau of Jiangsu Province of China (Grant Nos. 08KJB140002 and 09KJD430004)
文摘We theoretically studied the nonlocal Andreev reflection with Rashba spin-orbital interaction in a triple-quantumdot （QD） ring, which is introduced as Rashba spin-orbital interaction to act locally on one component quantum dot. It is found that the electronic current and spin current are sensitive to the systematic parameters. The interdot spin-flip term does not play a leading role in causing electronic and spin currents. Otherwise the spin precessing terra leads to shift of the peaks of the the spin-up and spin-down electronic currents in different directions and results in the spin current. Moreover, the spin-orbital interaction suppresses the nonlocal Andreev reflection, so we cannot obtain the pure spin current.
基金Project supported by the National Center of Science(Grant No.NN202 263138)
文摘We study spectroscopic signatures of a monochromatic boson mode interacting with a T-shape double quantum dot coupled between the metallic and superconducting leads. Focusing on a weak interdot coupling, we find that the proximity effect together with the bosonic mode are responsible for the series of Fano-type resonances appearing simultaneously at negative and positive energies. We investigate these interferometric features and discuss their influence on the subgap Andreev conductance taking into account the correlation effects driven by the Coulomb repulsion.
基金Project supported by the Special Funds of the National Natural Science Foundation of China (Grant Nos 10847133 and 10847132)the Natural Science Foundation of Education Bureau of Jiangsu Province,China (Grant No 08KJB140002)
文摘This paper theoretically reports the nonlocal Andreev reflection and spin current in a normal metal-ferromagnetic metal-superconducting Aharonov-Bohm interferometer. It is found that the electronic current and spin current are sensitive to systematic parameters, such as the gate voltage of quantum dots and the external magnetic flux. The electronic current in the normal metal lead results from two competing processes： quasiparticle transmission and nonlocal Andreev reflection. The appearance of zero spin-up electronic current （or spin-down electronic current） signals the existence of nonlocal Andreev reflection, and the presence of zero electronic current results in the appearance of pure spin current.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11204065 and 11474085)the Natural Science Foundation of Hebei Province,China(Grant Nos.A2013205168 and A2014205005)
文摘When two three-dimensional topological insulators （TIs） are brought close to each other with their surfaces aligned, the surfaces form a line junction. Similarly, three TI surfaces, not lying in a single plane, can form an atomic-scale nanostep junction. In this paper, Andreev reflection in a TI-TI-superconductor nanostep junction is investigated theoretically. Be- cause of the existence of edge states along each line junction, the conductance for a nanostep junction is suppressed. When the incident energy （e） of an electron is larger than the superconductor gap （A）, the Andreev conductance in a step junction is less than unity while for a plane junction it is unity. The Andreev conductance is found to depend on the height of the step junction. The Andreev conductance exhibits oscillatory behavior as a function of the junction height with the amplitude of the oscillations remaining unchanged when e = 0, but decreasing for e = A, which is different from the case of the plane junction. The height of the step is therefore an important parameter for Andreev reflection in nanostep junctions, and plays a role similar to that of the delta potential barrier in normal metal-superconductor plane junctions.
基金国家自然科学基金，国家自然科学基金，the State Key Laboratory for Mesoscopic Physics in Peking University
文摘We study Andreev tunneling through a ferromagnet/quantum-dot (QD)/superconductor system. By usingnonequilibrum Green function method, the averaged occupation of electrons in QD and the Andreev tunneling currentare studied. Comparing to the norma-metal/quantum-dot/superconductor, the system shows significant changes: (i)The averaged occupations of spin-up and spin-down electrons are not equal. (ii) With the increase of the polarizationof ferromagnetic lead, the Andreev reflection current decreases. (iii) However, even the ferromagnetic lead reaches fullpolarization, the averaged occupation of spin-down electrons is not zero. The physics of these changes is discussed.
基金the State Key Laboratory for Mesoscopic Physics in Peking University，国家自然科学基金
文摘We investigate the effect of intra-dot Coulomb interaction on the Andreev reflection in a normalmetal/quantum-dot/superconductor (N-QD-S) system with multiple levels in the quantum dot, in the regime where the intra-dot interacting constant is comparable to the energy gap of superconducting lead. By using nonequilibrium Green function method, the averaged occupation of electrons in the quantum dot and the Andreev reflection (AR) current are studied. Comparing to the case of non-interacting quantum dot, the system shows significant changes for the a two-step-like behavior; and the I-Vg shows two groups of peaks, separated by U and with equal heights, where Vg is the gate voltage and U denotes the intra-dot Coulomb interaction constant. (ii) For finite bias voltage, dips, superposed V ≥ U/2, extra AR current peaks occur between the two groups of the peaks. Besides, the properties of the heights of the AR current peaks are more complicated.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10074001 and 90103027 and the State KeyLaboratory for Mesoscopic Physics in Peking University
文摘We study Andreev tunneling through a ferromagnet/quantum-dot (QD)/superconductor system. By usingnonequilibrum Green function method, the averaged occupation of electrons in QD and the Andreev tunneling currentare studied. Comparing to the norma-metal/quantum-dot/superconductor, the system shows significant changes: (i)The averaged occupations of spin-up and spin-down electrons are not equal. (ii) With the increase of the polarizationof ferromagnetic lead, the Andreev reflection current decreases. (iii) However, even the ferromagnetic lead reaches fullpolarization, the averaged occupation of spin-down electrons is not zero. The physics of these changes is discussed.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11974153,12374034 and 11921005)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302403)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB28000000)。
文摘The Ising spin–orbit coupling could give rise to the spin-triplet Cooper pairs and equal-spin Andreev reflection(AR)in Ising superconductors.Here we theoretically study the valley-dependent equal-spin AR in a ferromagnet/Ising superconductor junction with a circularly polarized light applied to the ferromagnet.Because of the spin-triplet Cooper pairs and the optical irradiation,eight kinds of AR processes appear in the junction,including equal-spin AR and normal AR,the strengths and properties of which strongly depend on the valley degree of freedom.The AR probabilities for the incident electron from the two valleys exhibit certain symmetry with respect to the magnetization angle and the effective energy of light.The equal-spin AR and normal AR present different features and resonant behaviors near the superconducting gap edges.Due to equal-spin-triplet Cooper pairs,not only charge supercurrent but also spin supercurrent can transport in the Ising superconductors.The differential spin conductance for electron injecting from the two valleys can be controlled by the circularly polarized light.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12104232,11805103,and 11804167)the Natural Science Foundation of Jiangsu Province,China(Grant Nos.BK20190137 and BK20180739)+1 种基金the Innovation Research Project of Jiangsu Province,China(Grant No.CZ0070619002)NJUPT-SF(Grant No.NY218128)。
文摘We investigate the Andreev reflection across a uniaxial strained graphene-based superconducting junction.Compared with pristine graphene-based superconducting junction,three opposite properties are found.Firstly,in the regime of the interband conversion of electron–hole,the Andreev retro-reflection happens.Secondly,in the regime of the intraband conversion of electron–hole,the specular Andreev reflection happens.Thirdly,the perfect Andreev reflection,electron–hole conversion with unit efficiency,happens at a nonzero incident angle of electron.These three exotic properties arise from the strain-induced anisotropic band structure of graphene,which breaks up the original relation between the direction of velocity of particle and the direction of the corresponding wavevector.Our finding gives an insight into the understanding of Andreev reflection and provides an alternative method to modulate the Andreev reflection.
