2009
Mesaros, A.; Sadri, D.; Zaanen, J.
Berry phase of dislocations in graphene and valley conserving decoherence Tijdschriftartikel
In: PHYSICAL REVIEW B, vol. 79, nr. 15, 2009, ISSN: 2469-9950.
Abstract | Links | BibTeX | Tags: Aharonov-Bohm effect; Berry phase; dislocations; graphene; magnetoresistance
@article{WOS:000265944200042,
title = {Berry phase of dislocations in graphene and valley conserving
decoherence},
author = {A. Mesaros and D. Sadri and J. Zaanen},
doi = {10.1103/PhysRevB.79.155111},
issn = {2469-9950},
year = {2009},
date = {2009-04-01},
journal = {PHYSICAL REVIEW B},
volume = {79},
number = {15},
publisher = {AMER PHYSICAL SOC},
address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA},
abstract = {We demonstrate that dislocations in the graphene lattice give rise to
electron Berry phases equivalent to quantized values 0,+/- 1/3 in
units of the flux quantum but with an opposite sign for the two valleys.
An elementary scale consideration of a graphene Aharonov-Bohm ring
equipped with valley filters on both terminals, encircling a
dislocation, says that in the regime where the intervalley mean-free
path is large compared to the intravalley phase coherence length, such
that the valley quantum numbers can be regarded as conserved on the
relevant scale, the coherent valley-polarized currents sensitive to the
topological phases have to traverse the device many times before both
valleys contribute, and this is not possible at intermediate
temperatures where the latter length becomes of the order of the device
size, thus leading to an apparent violation of the basic law of linear
transport that magnetoconductance is even in the applied flux. We
discuss this discrepancy in the Feynman path picture of dephasing when
addressing the transition from quantum to classical dissipative
transport. We also investigate this device in the scattering matrix
formalism, accounting for the effects of decoherence by the Buttiker
dephasing voltage probe type model which conserves the valleys, where
the magnetoconductance remains even in the flux, also when different
decoherence times are allowed for the individual, time-reversal
connected, valleys.},
keywords = {Aharonov-Bohm effect; Berry phase; dislocations; graphene; magnetoresistance},
pubstate = {published},
tppubtype = {article}
}
We demonstrate that dislocations in the graphene lattice give rise to
electron Berry phases equivalent to quantized values 0,+/- 1/3 in
units of the flux quantum but with an opposite sign for the two valleys.
An elementary scale consideration of a graphene Aharonov-Bohm ring
equipped with valley filters on both terminals, encircling a
dislocation, says that in the regime where the intervalley mean-free
path is large compared to the intravalley phase coherence length, such
that the valley quantum numbers can be regarded as conserved on the
relevant scale, the coherent valley-polarized currents sensitive to the
topological phases have to traverse the device many times before both
valleys contribute, and this is not possible at intermediate
temperatures where the latter length becomes of the order of the device
size, thus leading to an apparent violation of the basic law of linear
transport that magnetoconductance is even in the applied flux. We
discuss this discrepancy in the Feynman path picture of dephasing when
addressing the transition from quantum to classical dissipative
transport. We also investigate this device in the scattering matrix
formalism, accounting for the effects of decoherence by the Buttiker
dephasing voltage probe type model which conserves the valleys, where
the magnetoconductance remains even in the flux, also when different
decoherence times are allowed for the individual, time-reversal
connected, valleys.
electron Berry phases equivalent to quantized values 0,+/- 1/3 in
units of the flux quantum but with an opposite sign for the two valleys.
An elementary scale consideration of a graphene Aharonov-Bohm ring
equipped with valley filters on both terminals, encircling a
dislocation, says that in the regime where the intervalley mean-free
path is large compared to the intravalley phase coherence length, such
that the valley quantum numbers can be regarded as conserved on the
relevant scale, the coherent valley-polarized currents sensitive to the
topological phases have to traverse the device many times before both
valleys contribute, and this is not possible at intermediate
temperatures where the latter length becomes of the order of the device
size, thus leading to an apparent violation of the basic law of linear
transport that magnetoconductance is even in the applied flux. We
discuss this discrepancy in the Feynman path picture of dephasing when
addressing the transition from quantum to classical dissipative
transport. We also investigate this device in the scattering matrix
formalism, accounting for the effects of decoherence by the Buttiker
dephasing voltage probe type model which conserves the valleys, where
the magnetoconductance remains even in the flux, also when different
decoherence times are allowed for the individual, time-reversal
connected, valleys.