Spin-Dependent Transport Signatures of Bound States: From Finger to Top Gates
Abstract:Spin-orbit gap feature in energy dispersion of
one-dimensional devices is revealed via strong spin-orbit interaction
(SOI) effects under Zeeman field. We describe the utilization
of a finger-gate or a top-gate to control the spin-dependent
transport characteristics in the SOI-Zeeman influenced split-gate
devices by means of a generalized spin-mixed propagation matrix
method. For the finger-gate system, we find a bound state in
continuum for incident electrons within the ultra-low energy regime.
For the top-gate system, we observe more bound-state features
in conductance associated with the formation of spin-associated
hole-like or electron-like quasi-bound states around band thresholds,
as well as hole bound states around the reverse point of the
energy dispersion. We demonstrate that the spin-dependent transport
behavior of a top-gate system is similar to that of a finger-gate system
only if the top-gate length is less than the effective Fermi wavelength.
 D. A. Wharam, T. J. Thornton, R. Newbury, M. Pepper, H. Ahmed,
J. E. F. Frost, D. G. Hasko, D. C. Peacock, D. A. Ritchie, G. A. C.
Jones, “One-dimensional transport and the quantisation of the ballistic
resistance”, J. Phys. C: Solid State Phys., vol. 21, pp.209-214, 1988.
 B. J. van Wees, H. van Houten, C. W. J. Beenakker, J. G. Williamson, L.
P. Kouwenhoven, D. van der Marel, C. T. Foxon, “Quantized Conductance
of Point Contacts in a Two-Dimensional Electron Gas”, Phys. Rev. Lett.,
vol. 60, no. 9, pp.848-850, 1988.
 K. J. Thomas, J. T. Nicholls, M. Y. Simmons, M. Pepper, D. R. Mace, and
D. A. Ritchie, “Possible Spin Polarization in a One-Dimensional Electron
Gas”, Phys. Rev. Lett., vol. 77, no. 1, pp.135-138, 1996.
 J. H. Bardarson, I. Magnusdottir, G. Gudmundsdottir, C.-S. Tang, A.
Manolescu, and V. Gudmundsson , “Coherent electronic transport in a
multimode quantum channel with Gaussian-type scatterers”, Phys. Rev.
B, vol. 70, no. 24, 245308, 2004.
 S. Datta and B. Das, “Electronic analog of the electro-optic modulator”,
Appl. Phys. Lett., vol. 56, pp.665-667, 1990.
 M. Governale, D. Boese, U. ZLulicke, and C. Schroll, “Filtering spin
with tunnel-coupled electron wave guides”, Phys. Rev. B, vol. 65, no. 14,
 A. Aharony, O. Entin-Wohlman, Y. Tokura, and S. Katsumoto, “Spin
filtering by a periodic spintronic device”, Phys. Rev. B, vol. 78, no.12,
 D. D. Awschalom, D. Loss, and N. Samarth, Semiconductor Sprintronics
and Quantum Computation (Springer, Berlin, 2002).
 A. G. Mal’shukov, C. S. Tang, C. S. Chu, and K. A. Chao, “Spin-current
generation and detection in the presence of an ac gate”, Phys. Rev. B,
vol. 68, no.23, 233307, 2003.
 A. G. Mal’shukov, C. S. Tang, C. S. Chu, and K. A. Chao,
“Strain-induced coupling of spin current to nanomechanical oscillations”,
Phys. Rev. Lett., vol. 95, no. 10, 107203, 2005.
 J. Nitta, T. Akazaki, H. Takayanagi, and T. Enoki, “Gate Control
of Spin-Orbit Interaction in an Inverted In0.53Ga0.47/In0.52Al0.48As
Heterostructure”, Phys. Rev. Lett., vol. 78, no. 7, pp.1335-1338, 1997.
 P. S. Eldridge, W. J. H. Leyland, P. G. Lagoudakis, O. Z. Karimov,
M. Henini, D. Taylor, R. T. Phillips, and R. T. Harley, “All-optical
measurement of Rashba coefficient in quantum wells”, Phys. Rev. B, vol.
77, no. 12, 125344, 2008.
 A. S. Sheremet, O. V. Kibis, A. V. Kavokin, and I. A.
Shelykh, “Datta-and-Das spin transistor controlled by a high-frequency
electromagnetic field”, Phys. Rev. B, vol. 93, no. 16, 165307, 2016.
 S. D. Ganichev and L. E. Golub, “Interplay of Rashba/Dresselhaus spin
splittings probed by photogalvanic spectroscopyVA review”, Phys. Status
Solidi B, vol. 251, pp.1801-1823, 2014.
 I. Zailer, J. E. F. Frost, V. Chabasseur-Molyneux, C. J. B. Ford,
and M. Pepper, “Crosslinked PMMA as a highresolution negative
resist for electron beam lithography and applications for physics of
low-dimensional structures”, Semicond. Sci. Technol., vol. 11, pp.
 C.-S. Tang, J.-A. Keng, N. R. Abdullah, V. Gudmundsson, “Spin
magneto-transport in a RashbaVDresselhaus quantum channel with single
and double finger gates”, Phys. Lett. A, vol. 381, pp. 1529-1533, 2017.
 C.-S. Tang, Y.-H. Yu, N. R. Abdullah, V. Gudmundsson, “Transport
signatures of top-gate bound states with strong RashbaVZeeman effect”,
Phys. Lett. A, vol. 381, pp. 3960-3963, 2017.
 S. Giglberger, L. E. Golub, V. V. Belkov, S. N. Danilov, D. Schuh,
C. Gerl, F. Rohlfing, J. Stahl,W.Wegscheider, D.Weiss, W. Prettl, and S.
D. Ganichev, “Rashba and Dresselhaus spin splittings in semiconductor
quantum wells measured by spin photocurrents”, Phys. Rev. B, vol. 75,
no. 3, 035327, 2007.
 C. L´opez-Bastidas, J. A. Maytorena, and F. Mireles, “Interplay of
the Rashba and Dresselhaus spin-orbit coupling in the optical spin
susceptibility of 2D electron systems”, Phys. Status Solidi C, vol. 4,
 Y. V. Pershin, J. A. Nesteroff, and V. Privman, “Effect of spin-orbit
interaction and in-plane magnetic field on the conductance of a
quasi-one-dimensional system”, Phys. Rev. B, vol. 69, no. 12, 121306(R),
 C. H. L. Quay, T. L. Hughes, J. A. Sulpizio, L. N. Pfeiffer,
K.W. Baldwin, K.W.West, D. Goldhaber-Gordon, and R. de Picciotto,
“Observation of a one-dimensional spinVorbit gap in a quantum wire”,
Nat. Phys., vol. 6, pp.336-339, 2010.
 C.-S. Tang, S. Y. Chang, and S. J. Cheng, “Finger-gate manipulated
quantum transport in a semiconductor narrow constriction with spin-orbit
interactions and Zeeman effect”, Phys. Rev. B, vol. 86, no. 12, 125321,
 A. F. Sadreev and E. Ya. Sherman, “Effect of gate-driven spin resonance
on the conductance through a one-dimensional quantum wire”, Phys. Rev.
B, vol. 88, no. 11, 115302, 2013.
 D. Rainis and D. Loss, “Conductance behavior in nanowires with
spin-orbit interaction: A numerical study”, Phys. Rev. B, vol. 90, no. 23,
 C.-S. Tang, S.-T. Tseng, V. Gudmundsson, and S.-J. Cheng,
“Double-finger-gate controlled spin-resolved resonant quantum transport
in the presence of a RashbaVZeeman gap”, J. Phys. Cond. Mat., vol. 27,
 R. Landauer, “Electrical resistance of disordered one-dimensional
lattices”, Philos. Mag., vol. 21, pp.863-867, 1970.
 M. B¨uttiker, “Quantized transmission of a saddle-point constriction”,
Phys. Rev. B, vol. 41, no. 11, pp.7906-7909, 1990.