Resistively detected NMR in a triple-gate quantum point contact: Magnetic field dependence

Noorhidayati, Annisa; Fauzi, M. H.; Sahdan, Muhammad Fauzi; Maeda, Shunta; Sato, Ken; Nagase, Kenzo; Hirayama, Y.

doi:10.1103/physrevb.101.035425

Cited by 6 publications

(11 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The electron mobility of the GaAs quantum well, on which the QPCs are fabricated, determines a broadening of the spin‐resolved Landau‐level as shown in Figure 1c so that the minimum magnetic field necessary for the RDNMR detection increases with decreasing the mobility. [ 11 ] Typical RDNMR signals obtained for high‐mobility (

μ = 1.47 \times 10^{6}

cm 2 V −1 s −1 at electron density of

1.8 \times 10^{11}

cm −2 ) and low‐mobility (

μ = 2.8 \times 10^{5}

cm 2 V −1 s −1 at electron density of

1.8 \times 10^{11}

cm −2 ) QPCs are shown in Figure 1d,e, respectively. They are obtained by setting

ν_{normalb} = 2

and

ν_{qpc}

slightly less than 1, corresponding to a strong tunneling regime discussed later.…”

Section: Basic Of Rdnmr In a Qpcmentioning

confidence: 99%

“…For the high‐mobility QPCs, we could clearly observe the RDNMR signal down to

B = 1.25

T. For the low‐mobility QPCs, successful observation of the signal is limited to

B > 3

T. However, all signals reflect the Larmor frequency of 75 As as shown in Figure 1f and, more importantly, both lineshape and broadening showed the same tendency, independent of the mobility. [ 11 ] It means that we can see intrinsic characteristics of the RDNMR signals even for the low‐mobility QPC device when we set the magnetic field high enough so that the up and down spin edge channels are well resolved.…”

Section: Basic Of Rdnmr In a Qpcmentioning

confidence: 99%

“…The Knight shift is proportional to the number of spin‐polarized electrons, so that the information provides us a hint about electron distribution in the channel. [ 11 ] Although many experiments including our previous experiments carried out in the regime of

ν_{qpc}

slightly less than 1 and the typical RDNMR signals are conductance peak (resistance dip), [ 8,10,11 ] the lineshapes changed depending on the experimental conditions and there is no systematic studies focusing on how the lineshapes change as a function of

ν_{qpc}

. In this article, we focus to the RDNMR lineshapes of the QPC in the quantum Hall breakdown regime with

0 < ν_{qpc} < 1

.…”

Section: Basic Of Rdnmr In a Qpcmentioning

confidence: 99%

“…[ 5,6,9 ] Although the RDNMR signal is mainly dominated by positive nuclear polarization, that is, parallel to the applied magnetic field, due to forward edge‐channel scattering events when

ν_{qpc}

is tuned slightly lower than 1. [ 8–11 ] However, the negative nuclear polarization also plays a role and a complicated dispersive line‐shape signal appears in some conditions. [ 9 ] The observed dispersive lineshapes have been reported in a two‐dimensional system [ 12–19 ] and are interpreted due to the formation of spin unpolarized puddles in the sea of spin‐polarized background.…”

Section: Introductionmentioning

confidence: 99%

“…Previous RDNMR studies are overwhelmingly reported in a single QPC device and in a strong tunneling regime between the two‐edge channels at the lowest Landau level. [ 8–11,20–23 ] In attempt to comprehensively study local hyperfine‐mediated transport in the lowest Landau level, in this study, we investigate RDNMR spectra in a wide range of local filling factor

0 < ν_{qpc} < 1

, encompassing strong to weak tunneling regime between the inner and outer edge channel at the lowest Landau level. Furthermore, we use a QPC device with multiple gate structures to control a potential shape in and near the QPC channel.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Resistively Detected NMR Lineshapes in a Local Filling ν<1 Quantum Hall Breakdown

Fauzi¹,

Sobue

Noorhidayati

et al. 2021

Physica Status Solidi (b)

Self Cite

View full text Add to dashboard Cite

Resistively‐detected nuclear magnetic resonance (RDNMR) is a unique characterization method enabling highly sensitive NMR detection for a single quantum nanostructure, such as a quantum point contact (QPC). In many studies, dynamic nuclear polarization and RDNMR detection are used in a quantum Hall breakdown regime of a local QPC filling factor of 1 (νqpc = 1). However, the RDNMR lineshapes are complicated and still not fully understood yet. Herein, the nuclear spins are systematically polarized by current pumping from the close vicinity of the νqpc = 1 conductance plateau all the way down to pinch‐off point, providing clear evidence that the spin‐flip scattering between two edge channels at the lowest Landau level still occurs in the constriction even when it is close to the pinch off point. The collected RDNMR spectra reveal two sets of distinguished features. First, in a strong to intermediate tunneling regime, we observe an ordinary resistance dip lineshape with snake‐like transition frequencies, indicative of spatial modulation of electron density in the QPC. Second, in a weak tunneling regime, the spectrum turns into a dispersive lineshape, which is interpreted due to the build‐up of two sets of nuclear spin polarization that are in contact with different electron spin polarization.

show abstract

μ = 1.47 \times 10^{6}

cm 2 V −1 s −1 at electron density of

1.8 \times 10^{11}

cm −2 ) and low‐mobility (

μ = 2.8 \times 10^{5}

cm 2 V −1 s −1 at electron density of

1.8 \times 10^{11}

cm −2 ) QPCs are shown in Figure 1d,e, respectively. They are obtained by setting

ν_{normalb} = 2

and

ν_{qpc}

slightly less than 1, corresponding to a strong tunneling regime discussed later.…”

Section: Basic Of Rdnmr In a Qpcmentioning

confidence: 99%

“…For the high‐mobility QPCs, we could clearly observe the RDNMR signal down to

B = 1.25

T. For the low‐mobility QPCs, successful observation of the signal is limited to

B > 3

Section: Basic Of Rdnmr In a Qpcmentioning

confidence: 99%

ν_{qpc}

ν_{qpc}

. In this article, we focus to the RDNMR lineshapes of the QPC in the quantum Hall breakdown regime with

0 < ν_{qpc} < 1

.…”

Section: Basic Of Rdnmr In a Qpcmentioning

confidence: 99%

“…[ 5,6,9 ] Although the RDNMR signal is mainly dominated by positive nuclear polarization, that is, parallel to the applied magnetic field, due to forward edge‐channel scattering events when