Chirality blockade of Andreev reflection in a magnetic Weyl semimetal

Bovenzi, N.; Breitkreiz, Maxim; Baireuther, Paul; O’Brien, Thomas E.; Tworzydło, J.; Adagideli, İnanç; Beenakker, C. W. J.

doi:10.1103/physrevb.96.035437

Cited by 46 publications

(68 citation statements)

References 36 publications

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“…4(b) and (c), where we have also taken the transverse momentum to be zero. As in the scattering matrix calculation, here again, the current oscillates as a function of both k 0 L/π and V 0 L/πv F , which clearly confirms the central result of our paper that inter-node Andreev reflection, if not prohibited by additional symmetries of the problem 32 , plays a crucial role in determining transport properties of the Weyl semimetalsuperconducting interface.…”

supporting

confidence: 88%

“…We summarize our results from the scattering matrix approach in Fig. 3 and we emphasize the following: first, the oscillation in the conductance is present even for normal-incidence, as expected from earlier results 13,21,32 which showed that the probability of normal-reflection at a WSM-SC junction is finite at normal incidence. Next, the oscillations in the conductance appear due to multiple reflections in the dot region, similar to those of a quantum mechanical double barrier problem.…”

supporting

confidence: 77%

“…A quantum dot made of WSM material in the presence of superconductors is of particular interest due to the distinctive nature of transport at a WSM-Superconductor (SC) interface 13,21,[30][31][32] and provides the possibility of capturing the otherwise elusive physics associated with the chiral excitation in the WSM 30 . In this manuscript we study transport through the Andreev states of a WSM quantum dot in a simple setup where we sandwich the dot in between a superconductor and a normal lead (see Fig.…”

mentioning

confidence: 99%

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Transport through Andreev bound states in a Weyl semimetal quantum dot

2017

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We study transport through a Weyl semimetal quantum dot sandwiched between an s-wave superconductor and a normal lead. The conductance peaks at regular intervals and exhibits double periodicity with respect to two characteristic frequencies of the system, one that originates from Klein tunneling in the system and the other coming from the chiral nature of the excitations. Using a scattering matrix approach as well as a lattice simulation, we demonstrate the universal features of the conductance through the system and discuss the feasibility of observing them in experiments.

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supporting

confidence: 88%

supporting

confidence: 77%

mentioning

confidence: 99%

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Transport through Andreev bound states in a Weyl semimetal quantum dot

2017

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“…Note.-During the review of our manuscript, we noticed the work of Bovenzi et al 58 . They study the normal and Andreev reflection processes at the junction of a WSM (with broken T symmetry) with a normal superconductor and observe that, while reflection within the same node is always blocked, Andreev reflection from one node to another can also be blocked at a WS junction if the interface or pair potential does not couple the two chiralities.…”

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confidence: 98%

0−π transitions in a Josephson junction of an irradiated Weyl semimetal

2017

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We propose a setup for the experimental realization of anisotropic 0-π transitions of the Josephson current, in a junction whose link is made of irradiated Weyl semi-metal (WSM), due to the presence of chiral nodes. The Josephson current through a time-reversal symmetric WSM has anisotropic (with respect to the orientation of the chiral nodes) periodic oscillations as a function of k0L, where k0 is the (relevant) separation of the chiral nodes and L is the length of the sample. We then show that the effective value of k0 can be tuned with precision by irradiating the sample with linearly polarized light, which does not break time-reversal invariance, resulting in 0-π transitions of the critical current. We also discuss the feasibility and robustness of our setup.

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“…(iii) Factors such as intervalley scattering, interfacial barrier, Fermi surface mismatch, and spatial profile of pair potential are inessential for the shift. And when symmetry argument applies, they have no effect on the value of the shift (as defined for a definite scattering process of the wavepacket), although they do affect the probability of the process [29,37].…”

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confidence: 99%

Transverse shift in Andreev reflection

Liu

Yang

2017

Phys. Rev. B

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An incoming electron is reflected back as a hole at a normal-metal-superconductor interface, a process known as Andreev reflection. We predict that there exists a universal transverse shift in this process due to the effect of spin-orbit coupling in the normal metal. Particularly, using both the scattering approach and the argument of angular momentum conservation, we demonstrate that the shifts are pronounced for lightly-doped Weyl semimetals, and are opposite for incoming electrons with different chirality, generating a chirality-dependent Hall effect for the reflected holes. The predicted shift is not limited to Weyl systems, but exists for a general three-dimensional spin-orbitcoupled metal interfaced with a superconductor.Spin-orbit coupling (SOC) underlies many topics that are at the frontier of current research. Intuitively, under SOC, the change of a particle's spin polarization will tend to alter its orbital motion. The effect is particularly pronounced when particles are scattered at certain interfaces. For example, when reflected at an interface, a circularly-polarized light beam acquires a transverse shift normal to its plane of incidence, known as ImbertFedorov shift [1][2][3][4][5][6], due to the intrinsic SOC of light [7]. Recently, an analogous transverse shift is predicted for Weyl electrons [8,9], the fermionic cousin of photons with strong SOC in so-called Weyl semimetals [10][11][12][13][14][15][16][17][18][19], when they are scattered by electrostatic potentials or velocity gradients. This discovery has generated great interest [20,21], and hints at possible universality of such effect in spin-orbit-coupled systems.There is an intriguing scattering process unique for the normal-metal-superconductor (NS) interface-Andreev reflection [22], in which an incoming electron excitation from the normal metal at energy ε above the Fermi level E F is reflected back as a hole excitation with energy ε below E F [23]. The process conserves energy and momentum but not charge: the missing charge of (−2e) is absorbed as a Cooper pair at Fermi level into the superconductor. For excitation energies below the superconducting gap, electrons cannot penetrate into the superconudctor, and Andreev reflection becomes the dominating mechanism for transport through the NS interface. A natural question arises: Is there a transverse shift associated with Andreev reflection? This question is not trivial, since the incoming and outgoing particles possess distinct identities with opposite charges. To our knowledge, it has not been posed or studied before.In this work, we answer the above question in the affirmative. We predict that a transverse shift generally exists in Andreev reflection between a three-dimensional spin-orbit-coupled metal and a conventional superconductor. We explicitly demonstrate the effect for two examples: a lightly-doped Weyl semimetal and a spin-orbitcoupled metal without any band-crossing. The result is derived via the quantum mechanical scattering approach, and in special cases can be exactly veri...

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Chirality blockade of Andreev reflection in a magnetic Weyl semimetal

Cited by 46 publications

References 36 publications

Transport through Andreev bound states in a Weyl semimetal quantum dot

Transport through Andreev bound states in a Weyl semimetal quantum dot

0−π transitions in a Josephson junction of an irradiated Weyl semimetal

Transverse shift in Andreev reflection

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