Bulk and surface states carried supercurrent in ballistic Nb-Dirac semimetal 
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 nanowire-Nb junctions

Li, Cai Zhen; Li, Chuan; Wang, Li Xian; Wang, Shuo; Liao, Zhi-Min; Brinkman, Alexander; Yu, Dakuan

doi:10.1103/physrevb.97.115446

Cited by 35 publications

(19 citation statements)

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“…Additional indications of the SC phase in Cd 3 As 2 were also observed in the point-contact spectroscopy experiments and attributed to the local crystal distortions under point-contact [19,20]. It is important to note, that up to now, all indications of the SC phase emergence in Cd 3 As 2 were related either to the pressureinduced structural changes or to the proximity effect with the conventional s-wave SC [21,22].Recent studies of Cd 3 As 2 thin films outlined their specific features. The observation of quantum Hall state [23,24] and consecutive analysis of magnetoresistance of Cd 3 As 2 films suggest the existence of closed Fermi loops (Weyl orbits) related to the surface states, below some critical thickness [25,26].…”

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confidence: 54%

Observation of subkelvin superconductivity in Cd3As2 thin films

et al. 2019

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We report the first experimental observation of superconductivity in Cd3As2 thin films without application of external pressure. Surface studies suggest that the observed transport characteristics are related to the polycrystalline continuous part of investigated films with homogeneous distribution of elements and the Cd-to-As ratio close to stoichiometric Cd3As2. The latter is also supported by Raman spectra of the studied films, which are similar to those of Cd3As2 single crystals. The formation of superconducting phase in films under study is confirmed by the characteristic behavior of temperature and magnetic field dependence of samples resistances, as well as by the presence of pronounced zero-resistance plateaux in dV /dI characteristics. The corresponding Hc−Tc plots reveal a clearly pronounced linear behavior within the intermediate temperature range, similar to that observed for bulk Cd3As2 and Bi2Se3 films under pressure, suggesting the possibility of nontrivial pairing in the films under investigation. We discuss a possible role of sample inhomogeneities and crystal strains in the observed phenomena.Weyl and Dirac semimetals (WSM and DSM) currently attract wide interest related to the existence of Dirac nodes in their electron spectrum and related nontrivial topological characteristics of both bulk and surface states [1][2][3]. A special attention is drawn to the Cd 3 As 2 compound, which proved to be air-stable, unlike some other DSM materials [4][5][6][7][8]. This compound is known and has been studied for quite a long time [9][10][11][12]. Nevertheless, it is still very popular since the Dirac nodes of this semimetal are protected by the crystal symmetry and the electron states exhibit interesting topological properties, such as spin-momentum locking. Due to the high symmetry, DSM materials can undergo transitions to other topological phases (e.g. WSM) as a result of breaking certain symmetries or applying some external factors.The existence of topologically protected electron states gives a new impetus to the problem of topological superconductivity (TSC) being discussed for a long time [13][14][15]. In particular, Refs. [16,17] provide a theoretical analysis of the possible types of SC pairing in the systems of Cd 3 As 2 type, including topologically nontrivial ones. Basically, the existence of nontrivial pairing potential (leading to the emergence of triplet Cooper pairs) should induce the formation of Majoranna modes at the surface of the crystal, which can be used in the faulttolerant quantum computing [14]. The SC phase emergence in Cd 3 As 2 was reported in Ref.[18], however, it was observed at pressures above the structural transition from the tetragonal to trigonal phase. While theoretical works suggest the stabilization of TSC phase upon such symmetry lowering [16,17], such transition also implies appearance of the gap at Dirac nodes, thus, suppressing the DSM phase. Additional indications of the SC phase in Cd 3 As 2 were also observed in the point-contact spectroscopy experiments and att...

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confidence: 54%

Observation of subkelvin superconductivity in Cd3As2 thin films

et al. 2019

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“…In this regard, we want to mention non-ambitiously observation of the Ic(sf,T) upturn reported by Li et al [44] in their Fig. 4 (a) at T = 2.5 K in Nb/Cd3As2-nanowire/Nb junction.…”

Section: Discussionmentioning

confidence: 84%

“…4 (a) at T = 2.5 K in Nb/Cd3As2-nanowire/Nb junction. However, raw experimental Ic(sf,T) dataset [44] was limited by measurements at T < 3.5 K, and thus, we are not able to perform the analysis for this very interesting atomically-narrow S/TI/S junction at the moment.…”

Section: Discussionmentioning

confidence: 99%

“…Many interesting physical effects are expected if non-superconducting part of S/N/S junction will be made of single-layer graphene (SLG) [7], multiple-layer graphene (MLG) [8], graphene-like materials [9], and many other new 2D-and nano-DCMs which are under on-going discover/invent/exploration stage now . One certainly interesting class of S/N/S junctions is when non-superconducting part of the device made of topological insulators (TI) [40][41][42][43][44][45][46][47]. Temperature dependent self-field critical currents, Ic(sf,T) in this class of junctions were first reported by Veldhorst et al in Nb/Bi2Te3/Nb [18], and later by Kurter et al in Nb/Bi2Se3/Nb [19], by Charpentier et al in Al/Bi2Te3/Al [42], and by other research groups in different systems (extended reference list for studied S/TI/S junctions can be found in Refs.…”

Section: Introductionmentioning

confidence: 99%

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Classifying Induced Superconductivity in Atomically Thin Dirac-Cone Materials

Talantsev

2019

Condensed Matter

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Recently, Kayyalha et al. (Phys. Rev. Lett., 2019, 122, 047003) reported on anomalous enhancement of the self-field critical currents, Ic(sf,T), at low temperatures in Nb/BiSbTeSe2nanoribbon/Nb Josephson junctions. The enhancement was attributed to the low-energy Andreev bound states arising from winding of the electronic wave function around the circumference of the topological insulator BiSbTeSe2 nanoribbon. In this paper, we show that identical enhancement in Ic(sf,T) and in the upper critical field, Bc2(T), at approximately same reduced temperatures, were reported by several research groups in atomically thin junctions based on a variety of Dirac-cone materials (DCM) earlier. Our analysis shows that in all these S/DCM/S systems the enhancement is due to a new superconducting band opening. Taking in account that several intrinsic superconductors also exhibit the effect of new superconducting band(s) opening when sample thickness becomes thinner than the ground state out-of-plane coherence length, c(0), we strength our previous proposal that there is a new phenomenon of additional superconducting band(s) opening in atomically thin films.

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“…1(a). Several junctions of different channel lengths were fabricated and investigated, revealing the surface states carried supercurrent [38]. In this work, we mainly focus on the unconventional rf response of the surface state transport.…”

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confidence: 99%

4π -Periodic Supercurrent from Surface States in Cd3As2 Nanowire-Base

Wang

et al. 2018

Phys. Rev. Lett.

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The combination of superconductivity and surface states in Dirac semimetal can produce a 4π-periodic supercurrent in a Josephson junction configuration, which can be revealed by the missing of odd Shapiro steps (especially the n ¼ 1 step). However, the suppression of the n ¼ 1 step is also anticipated in the high-power oscillatory regime of the ordinary 2π-periodic Josephson effect, which is irrelevant to the 4π-periodic supercurrent. Here, in order to identify the origin of the suppressed n ¼ 1 step, we perform the measurements of radio frequency irradiation on Nb-Dirac semimetal Cd 3 As 2 nanowire-Nb junctions with continuous power dependence at various frequencies. Besides the n ¼ 1 step suppression, we uncover a residual supercurrent of first node at the n ¼ 0 step, which provides a direct and predominant signature of the 4π-periodic supercurrent. Furthermore, by tuning the gate voltage, we can modulate the surface and bulk state contribution and the visibility of the n ¼ 1 step. Our results provide deep insights to explore the topological superconductivity in Dirac semimetals.

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Bulk and surface states carried supercurrent in ballistic Nb-Dirac semimetal Cd3As2 nanowire-Nb junctions

Cited by 35 publications

References 40 publications

Observation of subkelvin superconductivity in Cd3As2 thin films

Observation of subkelvin superconductivity in Cd3As2 thin films

Classifying Induced Superconductivity in Atomically Thin Dirac-Cone Materials

4π -Periodic Supercurrent from Surface States in Cd3As2 Nanowire-Base

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