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Angle-dependent magnetotransport in GaAs/InAs core/shell nanowires.

Haas F, Wenz T, Zellekens P, Demarina N, Rieger T, Lepsa M, Grützmacher D, Lüth H, Schäpers T - Sci Rep (2016)

Bottom Line: These are attributed to transport via angular momentum states, formed by electron waves within the InAs shell.Universal conductance fluctuations are observed for all tilt angles, however with increasing amplitudes for large tilt angles.We record this evolution of the electron propagation from a circling motion around the core to a diffusive transport through scattering loops and give explanations for the observed different transport regimes separated by the magnetic field orientation.

View Article: PubMed Central - PubMed

Affiliation: Peter Grünberg Institute 9, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.

ABSTRACT
We study the impact of the direction of magnetic flux on the electron motion in GaAs/InAs core/shell nanowires. At small tilt angles, when the magnetic field is aligned nearly parallel to the nanowire axis, we observe Aharonov-Bohm type h/e flux periodic magnetoconductance oscillations. These are attributed to transport via angular momentum states, formed by electron waves within the InAs shell. With increasing tilt of the nanowire in the magnetic field, the flux periodic magnetoconductance oscillations disappear. Universal conductance fluctuations are observed for all tilt angles, however with increasing amplitudes for large tilt angles. We record this evolution of the electron propagation from a circling motion around the core to a diffusive transport through scattering loops and give explanations for the observed different transport regimes separated by the magnetic field orientation.

No MeSH data available.


Related in: MedlinePlus

(a) Normalized amplitudes of the Fourier transformation of the magnetoconductance of sample B at low tilt angles and with high resolution to follow the evolution of the Aharonov–Bohm type oscillation pattern. The white dotted lines indicate the bounds of the frequency spreading with increased tilt proportional to sin (γ) as given by equation 3, caused by loop projections tilted in field as described in the text. (b) Medians of the frequency distribution from (a) determined from fitting a Gauss normal distribution on the data. The data is well described by a cosine dependence in tilt angle γ as described in the text. (c) The illustrations show contributions of different areas picking up magnetic flux. At parallel field (γ = 0°) mainly the perpendicular flux through the cross section determines the oscillations frequency. With increasing tilt, slightly tilted projections can also contribute to the oscillation pattern causing a spread of the observed frequencies.
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f5: (a) Normalized amplitudes of the Fourier transformation of the magnetoconductance of sample B at low tilt angles and with high resolution to follow the evolution of the Aharonov–Bohm type oscillation pattern. The white dotted lines indicate the bounds of the frequency spreading with increased tilt proportional to sin (γ) as given by equation 3, caused by loop projections tilted in field as described in the text. (b) Medians of the frequency distribution from (a) determined from fitting a Gauss normal distribution on the data. The data is well described by a cosine dependence in tilt angle γ as described in the text. (c) The illustrations show contributions of different areas picking up magnetic flux. At parallel field (γ = 0°) mainly the perpendicular flux through the cross section determines the oscillations frequency. With increasing tilt, slightly tilted projections can also contribute to the oscillation pattern causing a spread of the observed frequencies.

Mentions: To further analyse the evolution of the Aharonov–Bohm type oscillations with increasing tilt, we measured the magnetoconductance of sample B at low angles γB = 5° to 30° with higher resolution in angle and magnetic field. In Fig. 5(a) we have plotted the amplitudes of the Fourier spectrum of this measurement for these small tilt angles. High pass filtering was used on the differentiated data prior to Fourier transformation to remove the low frequency background and isolate the oscillation. The centre frequency of the flux periodic oscillations is moving to lower frequencies, as can be seen from Fig. 5(b) where we have fitted a Gauss normal distribution to the Fourier transformation of Fig. 5(a) to determine the frequencies median. Furthermore, the distribution of the frequency components becomes broader the further we tilt the nanowire away from the parallel orientation to the magnetic field.


Angle-dependent magnetotransport in GaAs/InAs core/shell nanowires.

Haas F, Wenz T, Zellekens P, Demarina N, Rieger T, Lepsa M, Grützmacher D, Lüth H, Schäpers T - Sci Rep (2016)

(a) Normalized amplitudes of the Fourier transformation of the magnetoconductance of sample B at low tilt angles and with high resolution to follow the evolution of the Aharonov–Bohm type oscillation pattern. The white dotted lines indicate the bounds of the frequency spreading with increased tilt proportional to sin (γ) as given by equation 3, caused by loop projections tilted in field as described in the text. (b) Medians of the frequency distribution from (a) determined from fitting a Gauss normal distribution on the data. The data is well described by a cosine dependence in tilt angle γ as described in the text. (c) The illustrations show contributions of different areas picking up magnetic flux. At parallel field (γ = 0°) mainly the perpendicular flux through the cross section determines the oscillations frequency. With increasing tilt, slightly tilted projections can also contribute to the oscillation pattern causing a spread of the observed frequencies.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4835758&req=5

f5: (a) Normalized amplitudes of the Fourier transformation of the magnetoconductance of sample B at low tilt angles and with high resolution to follow the evolution of the Aharonov–Bohm type oscillation pattern. The white dotted lines indicate the bounds of the frequency spreading with increased tilt proportional to sin (γ) as given by equation 3, caused by loop projections tilted in field as described in the text. (b) Medians of the frequency distribution from (a) determined from fitting a Gauss normal distribution on the data. The data is well described by a cosine dependence in tilt angle γ as described in the text. (c) The illustrations show contributions of different areas picking up magnetic flux. At parallel field (γ = 0°) mainly the perpendicular flux through the cross section determines the oscillations frequency. With increasing tilt, slightly tilted projections can also contribute to the oscillation pattern causing a spread of the observed frequencies.
Mentions: To further analyse the evolution of the Aharonov–Bohm type oscillations with increasing tilt, we measured the magnetoconductance of sample B at low angles γB = 5° to 30° with higher resolution in angle and magnetic field. In Fig. 5(a) we have plotted the amplitudes of the Fourier spectrum of this measurement for these small tilt angles. High pass filtering was used on the differentiated data prior to Fourier transformation to remove the low frequency background and isolate the oscillation. The centre frequency of the flux periodic oscillations is moving to lower frequencies, as can be seen from Fig. 5(b) where we have fitted a Gauss normal distribution to the Fourier transformation of Fig. 5(a) to determine the frequencies median. Furthermore, the distribution of the frequency components becomes broader the further we tilt the nanowire away from the parallel orientation to the magnetic field.

Bottom Line: These are attributed to transport via angular momentum states, formed by electron waves within the InAs shell.Universal conductance fluctuations are observed for all tilt angles, however with increasing amplitudes for large tilt angles.We record this evolution of the electron propagation from a circling motion around the core to a diffusive transport through scattering loops and give explanations for the observed different transport regimes separated by the magnetic field orientation.

View Article: PubMed Central - PubMed

Affiliation: Peter Grünberg Institute 9, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.

ABSTRACT
We study the impact of the direction of magnetic flux on the electron motion in GaAs/InAs core/shell nanowires. At small tilt angles, when the magnetic field is aligned nearly parallel to the nanowire axis, we observe Aharonov-Bohm type h/e flux periodic magnetoconductance oscillations. These are attributed to transport via angular momentum states, formed by electron waves within the InAs shell. With increasing tilt of the nanowire in the magnetic field, the flux periodic magnetoconductance oscillations disappear. Universal conductance fluctuations are observed for all tilt angles, however with increasing amplitudes for large tilt angles. We record this evolution of the electron propagation from a circling motion around the core to a diffusive transport through scattering loops and give explanations for the observed different transport regimes separated by the magnetic field orientation.

No MeSH data available.


Related in: MedlinePlus