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2. Width dependence of the 0.5 × (2e2/h) conductance plateau in InAs quantum point contacts in presence of lateral spin-orbit coupling

Author

Department of Physics, National Institute of Technology Karnataka, Surathkal, 575025, India, Spintronics and Vacuum Nanoelectronics Laboratory, University of Cincinnati, Cincinnati, Ohio, 45040, USA, Department of Electronics and Communication Engineering, Tezpur University, Tezpur, Assam, 784028, India, Department of Chemistry, National Institute of Technology Karnataka, Surathkal, 575025, India, Department of Materials Science and Engineering, Kyushu Institute of Technology, Tobata-ku, Kitakyushu, 804-8550, Japan, Das, Partha Pratim, Cahay, Marc, Kalita, Shashikala, Mal, Sib Sankar, Jha, Alok Kumar, Department of Physics, National Institute of Technology Karnataka, Surathkal, 575025, India, Spintronics and Vacuum Nanoelectronics Laboratory, University of Cincinnati, Cincinnati, Ohio, 45040, USA, Department of Electronics and Communication Engineering, Tezpur University, Tezpur, Assam, 784028, India, Department of Chemistry, National Institute of Technology Karnataka, Surathkal, 575025, India, Department of Materials Science and Engineering, Kyushu Institute of Technology, Tobata-ku, Kitakyushu, 804-8550, Japan, Das, Partha Pratim, Cahay, Marc, Kalita, Shashikala, Mal, Sib Sankar, and Jha, Alok Kumar

Abstract

type:Journal Article, The evolution of the 0.5Go (Go = 2e2/h) conductance plateau and the accompanying hysteresis loop in a series of asymmetrically biased InAs based quantum point contacts (QPCs) in the presence of lateral spin-orbit coupling (LSOC) is studied using a number of QPCs with varying lithographic channel width but fixed channel length. It is found that the size of the hysteresis loops is larger for QPCs of smaller aspect ratio (QPC channel width/length) and gradually disappears as their aspect ratio increases. The physical mechanisms responsible for a decrease in size of the hysteresis loops for QPCs with increasing aspect ratio are: (1) multimode transport in QPCs with larger channel width leading to spin-flip scattering events due to both remote impurities in the doping layer of the heterostructure and surface roughness and impurity (dangling bond) scattering on the sidewalls of the narrow portion of the QPC, and (2) an increase in carrier density resulting in a screening of the electron-electron interactions in the QPC channel. Both effects lead to a progressive disappearance of the net spin polarization in the QPC channel and an accompanying reduction in the size of the hysteresis loops as the lithographic width of the QPC channel increases.

Published
2020

3. Width dependence of the 0.5 × (2e2/h) conductance plateau in InAs quantum point contacts in presence of lateral spin-orbit coupling.

Author

Das, Partha Pratim, Cahay, Marc, Kalita, Shashikala, Mal, Sib Sankar, and Jha, Alok Kumar

Subjects
HYSTERESIS loop, SURFACE roughness, CARRIER density, CONDUCTION bands, NANOWIRES
Abstract

The evolution of the 0.5Go (Go = 2e2/h) conductance plateau and the accompanying hysteresis loop in a series of asymmetrically biased InAs based quantum point contacts (QPCs) in the presence of lateral spin-orbit coupling (LSOC) is studied using a number of QPCs with varying lithographic channel width but fixed channel length. It is found that the size of the hysteresis loops is larger for QPCs of smaller aspect ratio (QPC channel width/length) and gradually disappears as their aspect ratio increases. The physical mechanisms responsible for a decrease in size of the hysteresis loops for QPCs with increasing aspect ratio are: (1) multimode transport in QPCs with larger channel width leading to spin-flip scattering events due to both remote impurities in the doping layer of the heterostructure and surface roughness and impurity (dangling bond) scattering on the sidewalls of the narrow portion of the QPC, and (2) an increase in carrier density resulting in a screening of the electron-electron interactions in the QPC channel. Both effects lead to a progressive disappearance of the net spin polarization in the QPC channel and an accompanying reduction in the size of the hysteresis loops as the lithographic width of the QPC channel increases. [ABSTRACT FROM AUTHOR]

Published
2019
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