University of Cambridge > Talks.cam > Semiconductor Physics Group Seminars > Multiplexer on the 0.7 anomaly in quantum point contacts (SP Workshop)

Multiplexer on the 0.7 anomaly in quantum point contacts (SP Workshop)

Add to your list(s) Download to your calendar using vCal

If you have a question about this talk, please contact Teri Bartlett.

The ‘0.7 anomaly’ refers to an unexpected shoulder at ~0.7*(2e2/h) in the linear conductance of a quantum point contact (QPC) [1], which occurs as a result of electron-electron (e-e) interactions. However, its origin is still under debate over twenty years. We measured thousands of QPC devices using a multiplexer statistic technique [2-3] and try to experimentally verify a recent van Hove scenario theory [4] that governs the 0.7 anomaly, compared with the phenomenological model of spontaneous spin polarization. VG Dependence: By sweeping the split-gate voltage (VG), the 0.7 anomaly forms at the maximum of the van Hove ridge-like local density of states (LDOS), which amplifies the e-e interactions to be strongest and thus make the suppression of conductance largest. Ex Dependence: Decreasing the curvature of the longitudinal potential barrier (Ex) has qualitatively similar effects compared with increasing e-e interaction strength, in that both can cause the 0.7 anomaly more prominent. B Dependence: In low parallel field, the magnetoconductance depends quadratically on the field in the sub-open regime. This Fermi-liquid property links the magnetoresponse strength to the local spin susceptibility fluctuations, which is largest also at the maximum of LDOS .

Reference:

[1] K. J. Thomas et al Phys. Rev. Lett. 77, 135 (1996) [2] H. Al-Taie et al App. Phys. Lett. 102, 243102 (2013) [3] L. W. Smith et al Phys. Rev. Applied 5, 044015 (2016) [4] F. Bauer et al Nature 501, 73 (2013).

This talk is part of the Semiconductor Physics Group Seminars series.

Tell a friend about this talk:

This talk is included in these lists:

Note that ex-directory lists are not shown.

 

© 2006-2024 Talks.cam, University of Cambridge. Contact Us | Help and Documentation | Privacy and Publicity