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Induced superconductivity in high-mobility two-dimensional electron gas in gallium arsenide heterostructures.

Wan Z, Kazakov A, Manfra MJ, Pfeiffer LN, West KW, Rokhinson LP - Nat Commun (2015)

Bottom Line: Search for Majorana fermions renewed interest in semiconductor-superconductor interfaces, while a quest for higher-order non-Abelian excitations demands formation of superconducting contacts to materials with fractionalized excitations, such as a two-dimensional electron gas in a fractional quantum Hall regime.Here we report induced superconductivity in high-mobility two-dimensional electron gas in gallium arsenide heterostructures and development of highly transparent semiconductor-superconductor ohmic contacts.High critical fields (>16 T) in NbN contacts enables investigation of an interplay between superconductivity and strongly correlated states in a two-dimensional electron gas at high magnetic fields.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, USA.

ABSTRACT
Search for Majorana fermions renewed interest in semiconductor-superconductor interfaces, while a quest for higher-order non-Abelian excitations demands formation of superconducting contacts to materials with fractionalized excitations, such as a two-dimensional electron gas in a fractional quantum Hall regime. Here we report induced superconductivity in high-mobility two-dimensional electron gas in gallium arsenide heterostructures and development of highly transparent semiconductor-superconductor ohmic contacts. Supercurrent with characteristic temperature dependence of a ballistic junction has been observed across 0.6 μm, a regime previously achieved only in point contacts but essential to the formation of well separated non-Abelian states. High critical fields (>16 T) in NbN contacts enables investigation of an interplay between superconductivity and strongly correlated states in a two-dimensional electron gas at high magnetic fields.

No MeSH data available.


Related in: MedlinePlus

Temperature dependence of superconductivity in a ballistic junction.(a) Evolution of the induced superconductivity with T for sample B. The R(I) curves are offset proportional to T for T>50 mK. (b) Temperature dependence of critical current Ic(T) is extracted from (a) and compared with the expected T-dependence for ballistic and diffusive regimes (reduced Ic compared with Fig. 2 is due to larger Ia.c.=10 nA used in this experiment). (c) High-temperature data shows Andreev reflection (excess current and reduced dV/dI around V=0. The curves are not offset. In d, excess current is modelled within the Blonder–Tinkham–Klapwijk theory39 with Z=0.2.
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f3: Temperature dependence of superconductivity in a ballistic junction.(a) Evolution of the induced superconductivity with T for sample B. The R(I) curves are offset proportional to T for T>50 mK. (b) Temperature dependence of critical current Ic(T) is extracted from (a) and compared with the expected T-dependence for ballistic and diffusive regimes (reduced Ic compared with Fig. 2 is due to larger Ia.c.=10 nA used in this experiment). (c) High-temperature data shows Andreev reflection (excess current and reduced dV/dI around V=0. The curves are not offset. In d, excess current is modelled within the Blonder–Tinkham–Klapwijk theory39 with Z=0.2.

Mentions: The most attractive property of a high-mobility 2DEG is large mean free path l≫ξ0, with l=24 μm and the Bardeen-Cooper-Schrieffer (BCS) coherence length ξ0=ℏvF/πΔ=0.72 μm for sample B. Here is the Fermi velocity, n is a 2D gas density, m is an effective mass and Δ=1.76kBTc=46 μeV is the induced superconducting gap. Evolution of V(I) with T is shown in Fig. 3a. Experimentally obtained T-dependence of Ic is best described by the Kulik–Omelyanchuk theory for ballistic junctions (L<<l) (ref. 35), the blue curve in Fig. 3b. For comparison, we also plot Ic(T) dependence for the dirty limit (ref. 36), which exhibits characteristic saturation of Ic at low temperatures.


Induced superconductivity in high-mobility two-dimensional electron gas in gallium arsenide heterostructures.

Wan Z, Kazakov A, Manfra MJ, Pfeiffer LN, West KW, Rokhinson LP - Nat Commun (2015)

Temperature dependence of superconductivity in a ballistic junction.(a) Evolution of the induced superconductivity with T for sample B. The R(I) curves are offset proportional to T for T>50 mK. (b) Temperature dependence of critical current Ic(T) is extracted from (a) and compared with the expected T-dependence for ballistic and diffusive regimes (reduced Ic compared with Fig. 2 is due to larger Ia.c.=10 nA used in this experiment). (c) High-temperature data shows Andreev reflection (excess current and reduced dV/dI around V=0. The curves are not offset. In d, excess current is modelled within the Blonder–Tinkham–Klapwijk theory39 with Z=0.2.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4490403&req=5

f3: Temperature dependence of superconductivity in a ballistic junction.(a) Evolution of the induced superconductivity with T for sample B. The R(I) curves are offset proportional to T for T>50 mK. (b) Temperature dependence of critical current Ic(T) is extracted from (a) and compared with the expected T-dependence for ballistic and diffusive regimes (reduced Ic compared with Fig. 2 is due to larger Ia.c.=10 nA used in this experiment). (c) High-temperature data shows Andreev reflection (excess current and reduced dV/dI around V=0. The curves are not offset. In d, excess current is modelled within the Blonder–Tinkham–Klapwijk theory39 with Z=0.2.
Mentions: The most attractive property of a high-mobility 2DEG is large mean free path l≫ξ0, with l=24 μm and the Bardeen-Cooper-Schrieffer (BCS) coherence length ξ0=ℏvF/πΔ=0.72 μm for sample B. Here is the Fermi velocity, n is a 2D gas density, m is an effective mass and Δ=1.76kBTc=46 μeV is the induced superconducting gap. Evolution of V(I) with T is shown in Fig. 3a. Experimentally obtained T-dependence of Ic is best described by the Kulik–Omelyanchuk theory for ballistic junctions (L<<l) (ref. 35), the blue curve in Fig. 3b. For comparison, we also plot Ic(T) dependence for the dirty limit (ref. 36), which exhibits characteristic saturation of Ic at low temperatures.

Bottom Line: Search for Majorana fermions renewed interest in semiconductor-superconductor interfaces, while a quest for higher-order non-Abelian excitations demands formation of superconducting contacts to materials with fractionalized excitations, such as a two-dimensional electron gas in a fractional quantum Hall regime.Here we report induced superconductivity in high-mobility two-dimensional electron gas in gallium arsenide heterostructures and development of highly transparent semiconductor-superconductor ohmic contacts.High critical fields (>16 T) in NbN contacts enables investigation of an interplay between superconductivity and strongly correlated states in a two-dimensional electron gas at high magnetic fields.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, USA.

ABSTRACT
Search for Majorana fermions renewed interest in semiconductor-superconductor interfaces, while a quest for higher-order non-Abelian excitations demands formation of superconducting contacts to materials with fractionalized excitations, such as a two-dimensional electron gas in a fractional quantum Hall regime. Here we report induced superconductivity in high-mobility two-dimensional electron gas in gallium arsenide heterostructures and development of highly transparent semiconductor-superconductor ohmic contacts. Supercurrent with characteristic temperature dependence of a ballistic junction has been observed across 0.6 μm, a regime previously achieved only in point contacts but essential to the formation of well separated non-Abelian states. High critical fields (>16 T) in NbN contacts enables investigation of an interplay between superconductivity and strongly correlated states in a two-dimensional electron gas at high magnetic fields.

No MeSH data available.


Related in: MedlinePlus