Spatial detection of 1D double-row formation using transverse magnetic focusing technique
Heng-Jian Chang1*, Chiahua Chang1, Sheng-Chin Ho1, G. Creeth2, I. Farrer2, D.A. Ritchie2, T.-M. Chen1
1Department of Physics, National Cheng Kung University, Tainan, Taiwan
2Cavendish Laboratory, University of Cambridge, Cambridge, United Kingdom
* presenting author:張恆健,
It is established that the one-dimensional (1D) system in a quantum point contact can bifurcate into two electron rows when the electron-electron interactions within the channel overcome the confinement potential, which can be achieved by tuning the carrier density as well as the confinement [1]. Previous studies, which were performed on quantum point contacts consisting of two pairs of split gates and a top gate, imply that the double-row forms when quantum point contacts are experimentally tuned to be weakly confined [2]. However, direct observation of the double-row formation is still absent.
Here, we design a device which is based on magnetic focusing geometry [3,4] but with an additional top gate to directly detect the double-row formation. By the means of measuring focusing peaks, we could study the physics of double row transport within the channel. Focusing peaks are expected to gradually spread into two peaks, as the double-rows form. This experiment allows us to verify the double-row transport and investigate the electron-electron interactions in a quantum point contact.

[1] G. Piacente et al., Phys. Rev. B 69 045324 (2004)
[2] L.W. Smith et al., Phys. Rev. B 80 041306 (2009)
[3] R.M. Potok et al., Phys. Rev Lett. 89 266602 (2002)
[4] T.-M. Chen et al., Phys. Rev Lett. 109 17202 (2012)

Keywords: double-row, magnetic focusing