Chiral anomaly induced oscillations in the Josephson current in Weyl semimetals

Uddin, Salah; Duan, Wenye; Wang, Jun; Ma, Zhongshui; Liu, Jun-Feng

doi:10.1103/physrevb.99.045426

Cited by 16 publications

(8 citation statements)

References 54 publications

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“…When there is no light field applied, the critical current exhibits a smooth oscillation behavior as the junction length increasing. The smooth oscillation is attributed to the normal multi-reflection at the normal metal/superconductor interfaces and indicates that the junction is always in the 0-state [50]. When the light field is on, the critical current curve shows some cuspidal dips, which indicate the 0-π transition.…”

Section: A Kek-o Patterned Junctionmentioning

confidence: 97%

Light-modulated Josephson effect in Kekulé patterned graphene

Zeng,

Shen

2021

Preprint

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We theoretically study the Josephson effect in a superconductor/normal metal/superconductor junction based on Kekulé patterned graphene. For the Kekulé-O patterned junctions, a Fermi momentum-splitting Andreev reflection at the interface can be induced by the off-resonant circularly polarized light applied in the normal region, which results in the possible π-state. In contrast, for the Kekulé-Y patterned junctions, the Fermi momentum-splitting Andreev reflection is strongly suppressed due to the valley-momentum locking and the junction always exhibits the 0-state. The dependence of the critical current on the junction length and the illumination parameter of the light field is also presented in detail. I. INTRODUCTIONKekulé (Kek) patterned graphene is a two-dimensional superlattice consisting of periodic thin and thick atomic bonds [1][2][3][4]. These alternating bonds form a √ 3 × √ 3 supercell, where the K and K valleys of the pristine graphene are folded on top of each other [5][6][7]. Recent experiments demonstrated that a carbon atom-centered bond texture can be realized in the graphene sheet grown on Cu(111) [4,8], which is known as the Kek-Y patterned graphene. The valley-momentum locking[5] predicted in this system leads to many peculiar properties, such as the enhanced Andreev reflection[9], the valley precession effect[10], the resonant transport [11], and the tunable optical absorption [12]. However, the pattern in which the C-C bond strength is altered as in a benzene ring is known as the Kek-O bond texture with a gap opened at the Dirac point[5]. Recently, in the Kek-O patterned graphene, Beenakker et al. predicted a valley switch effect by use of the Andreev-like reflection[13] and Wang et al. subsequently reported the valley supercurrent[14].The Josephson effect is an example of a macroscopic quantum phenomenon first predicted by B. D Josephson in 1962[15, 16]. A Josephson junction consists of two superconductors coupled by a weak link [17][18][19][20][21]. The current flowing continuously across the junction without any voltage applied is called the dc Josephson current [22][23][24][25], which is driven by the superconducting phase difference φ and can be expressed as I ∼ sin(φ + φ 0 ) with φ 0 representing the additional phase shift. The ground state of the junction usually has a zero phase shift at φ 0 = 0 due to the time-reversal symmetry [26][27][28]. With a ferromagnetic link, an extra π phase shift can appear in the junction leading to the π-state junctions with the supercurrent reversals [29][30][31][32][33]. As an analogy to the spin polarization, several studies have revealed that the valley isospin polarizations in graphene-like materials can also result in the π-state junctions, such as the irradiated graphene-and silicene-based Josephson junctions [34,35].

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Section: A Kek-o Patterned Junctionmentioning

confidence: 97%

Light-modulated Josephson effect in Kekulé patterned graphene

Zeng,

Shen

2021

Preprint

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“…These include superconductor -ferromagnet-superconductor Josephson junction 29,30 , Josephson junction with unconventional superconducting order parameter 31,32 , Josephson junctions based on topological insulators or nanowire in presence of Zeeman field [33][34][35] , Josephson junction of an irradiated Weyl semimetal 36 and strong spin-orbit coupled two dimensional materials 37 . A chirality imbalanced potential also leads 0-π transition for BCS-like pairing of a TR broken WSM 38 . The anomalous supercurrent can flow in φ state with a free energy ground state other than 0 or π 39,40 .…”

Section: Introductionmentioning

confidence: 94%

“…The ABS for H − B is obtained by replacing (36,37) and φ t → −φ t in Eq. (38). The total Josephson current is now given by,…”

Section: B Bcs-like Pairingmentioning

confidence: 99%

Josephson effect in type-I Weyl Semimetals

Sinha

2020

Preprint

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The emergent Weyl fermions in condensed matter generally break the Lorentz invariance resulting in a tilted (type-I) or over-tilted (type-II) energy dispersion. The tilting energy spectrums can lead to exotic quantum interference effects in a junction set up. Here, we theoretically investigate the Josephson current in a Weyl superconductor-Weyl (semi)metal-Weyl superconductor junction of a time-reversal (TR) broken type-I Weyl semimetal. We demonstrate that the Cooper pairs of BCS-like pairing acquire a finite momentum in case of inversion symmetric tilt. Consequently, the system exhibits tilt induced anomalous current phase relations which are manifested by supercurrent 0-π transition and Josephson φ junction. On the contrary, these effects remain absent in case of inversion breaking tilt and for FFLO-like pairing in the Weyl superconductor. We further chart out qualitative differences between the two distinct types of pairings by studying the critical current dependency on junction length. Our study opens a new avenue to probe the unconventional superconducting pairings in TR-broken Weyl semimetals. It is also quite interesting that the tilting in Weyl nodes naturally leads to anomalous current phase relations in this model without any magnetic manipulation!

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“…An alternative route to achieve superconducting phases in Weyl semimetals is to make use of the proximity-induced superconductivity in heterostructures by combining an otherwise non-superconducting Weyl semimetal (N) and a conventional superconductor (S) [17][18][19][20]. One prominent type of such heterostructures is the Josephson junction (SNS-heterostructure), which has been extensively studied theoretically exploring the influence of various types of superconducting pairing mechanisms [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35], and has also been realized experimentally [19,[36][37][38][39][40]. Other examples of similar heterostructures are NS-type [17,20,[41][42][43][44][45][46][47][48][49][50][51], and NSN-type [52][53][54][55][56] heterostructures.…”

Section: Introductionmentioning

confidence: 99%

Equilibrium current in a Weyl-semimetal - superconductor heterostructure

Madsen,

Brouwer,

Breitkreiz

2021

Preprint

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A heterostructure consisting of a magnetic Weyl semimetal and a conventional superconductor exhibits an equilibrium current parallel to the superconductor interface and perpendicular to the magnetization. Analyzing a minimal model, which as a function of parameters may be in a trivial magnetic insulator phase, a Weyl semimetal phase, or a three-dimensional weak Chern insulator phase, we find that the equilibrium current is sensitive to the presence of surface states, such as the topological Fermi-arc states of the Weyl semimetal or the chiral surface states of the weak Chern insulator. While there is a nonzero equilibrium current in all three phases, the appearance of the surface states in the topological regime leads to a reversal of the direction of the current, compared to the current direction for the trivial magnetic insulator phase. We discuss the interpretation of the surface-state contribution to the equilibrium current as a real-space realization of the superconductivity-enabled equilibrium chiral magnetic effect of a single chirality, predicted to occur in bulk Weyl superconductors.

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Chiral anomaly induced oscillations in the Josephson current in Weyl semimetals

Cited by 16 publications

References 54 publications

Light-modulated Josephson effect in Kekulé patterned graphene

Light-modulated Josephson effect in Kekulé patterned graphene

Josephson effect in type-I Weyl Semimetals

Equilibrium current in a Weyl-semimetal - superconductor heterostructure

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