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Andreev Reflection at the Interface with an Oxide in the Quantum Hall Regime

Kozuka, Yusuke and Sakaguchi, Atsushi and Falson, Joseph and Tsukazaki, Atsushi and Kawasaki, Masashi (2018) Andreev Reflection at the Interface with an Oxide in the Quantum Hall Regime. Journal of the Physical Society of Japan, 87 (12). Art. No. 124712. ISSN 0031-9015. doi:10.7566/jpsj.87.124712.

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Quantum Hall/superconductor junctions have been an attractive topic as the two macroscopically quantum states join at the interface. Despite longstanding efforts, however, experimental understanding of this system has not been settled yet. One of the reasons is that most semiconductors hosting high-mobility two-dimensional electron systems (2DES) usually form Schottky barriers at the metal contacts, preventing efficient proximity between the quantum Hall edge states and Cooper pairs. Only recently have relatively transparent 2DES/superconductor junctions been investigated in graphene. In this study, we propose another material system for investigating 2DES/superconductor junctions, that is ZnO-based heterostructure. Due to the ionic nature of ZnO, a Schottky barrier is not effectively formed at the contact with a superconductor MoGe, as evidenced by the appearance of Andreev reflection at low temperatures. With applying magnetic field, while clear quantum Hall effect is observed for ZnO 2DES, conductance across the junction oscillates with the filling factor of the quantum Hall states. We find that Andreev reflection is suppressed in the well developed quantum Hall regimes, which we interpret as a result of equal probabilities of normal and Andreev reflections as a result of multiple Andreev reflection at the 2DES/superconductor interface.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper ItemCommentary
Kozuka, Yusuke0000-0001-7674-600X
Falson, Joseph0000-0003-3183-9864
Tsukazaki, Atsushi0000-0003-0251-063X
Kawasaki, Masashi0000-0001-6397-4812
Additional Information:© 2018 The Physical Society of Japan. Received May 31, 2018; Accepted November 6, 2018; Published December 3, 2018. We appreciate T. Tamegai and M. Kawamura for valuable suggestions. This research was supported by JST, PRESTO Grant Number JPMJPR1763 and JST, CREST Grant Number JPMJCR16F1, Japan, as well as by Mitsubishi Foundation (Y.K.). This work was carried out by joint research of the Cryogenic Research Center, the University of Tokyo.
Funding AgencyGrant Number
Japan Science and Technology AgencyJPMJPR1763
Japan Science and Technology AgencyJPMJCR16F1
Mitsubishi FoundationUNSPECIFIED
Issue or Number:12
Record Number:CaltechAUTHORS:20200402-144732537
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Official Citation:Andreev Reflection at the Interface with an Oxide in the Quantum Hall Regime Yusuke Kozuka, Atsushi Sakaguchi, Joseph Falson, Atsushi Tsukazaki, Masashi Kawasaki Journal of the Physical Society of Japan, 87, 124712 (2018) 10.7566/JPSJ.87.124712
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:102283
Deposited By: George Porter
Deposited On:03 Apr 2020 17:32
Last Modified:16 Nov 2021 18:10

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