Rashba spin–orbit coupling and spin precession in carbon nanotubes

Martino, Alessandro De; Egger, Reinhold

doi:10.1088/0953-8984/17/36/008

Cited by 17 publications

(24 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The additional term, the diagonal term of eq. (5.2), would give a chirality dependence on not only the energy band structure, but also on time evolution 47,48) and relaxation mechanism 36) of the electron spin in carbon nanotubes. Other types of spin-orbit interaction, e.g.…”

Section: Discussionmentioning

confidence: 99%

Spin–Orbit Interaction in Single Wall Carbon Nanotubes: Symmetry Adapted Tight-Binding Calculation and Effective Model Analysis

2009

View full text Add to dashboard Cite

Energy band for single wall carbon nanotubes with spin-orbit interaction is calculated using nonorthogonal tight-binding method. A Bloch function with spin degree of freedom is introduced to adapt the screw symmetry of nanotubes. The energy gap opened by spin-orbit interaction for armchair nanotubes, and the energy band splitting for chiral and zigzag nanotubes are evaluated quantitatively. Spin polarization direction for each split band is shown to be parallel to the nanotube axis. The energy gap and the energy splitting depend on the diameter and chirality in an energy scale of sub-milli-electron volt. An effective model for reproducing the low energy band structure shows that the two mechanism of the band modification, shift of the energy band in two dimensional reciprocal lattice space, and, effective Zeeman energy shift, are relevant. The effective model explains well the energy gap and splitting for more than 300 nanotubes within the diameter between 0.7 to 2.5 nm.

show abstract

Section: Discussionmentioning

confidence: 99%

Spin–Orbit Interaction in Single Wall Carbon Nanotubes: Symmetry Adapted Tight-Binding Calculation and Effective Model Analysis

2009

View full text Add to dashboard Cite

show abstract

Section: Figure 1 Describes the Spin-valve Device (See Methodsmentioning

confidence: 99%

“…Oscillation of the spin-valve signal with V g due to spin-orbit coupling has been proposed as the basis of a spin transistor 23 . However, the spin-orbit coupling in graphene is expected to be very small 9 , and this effect should not be observable 24 . Oscillations and sign changes of the spin-valve signal have also been observed when the spin current flows through a resonant quantum state, either due to Coulomb blockade 25 or resonant tunneling 6 .…”

mentioning

confidence: 99%

Gate-tunable graphene spin valve

Cho

Chen

Fuhrer

2007

Applied Physics Letters

273

197

View full text Add to dashboard Cite

First we discuss whether R nl arises due to charge current or spin current flowing between F3 and F4. Ideally, charge current would flow only between F3 and F2, eliminating contributions to the R nl from magnetoresistance of the ferromagnetic electrodes (anisotropic magnetoresistance), the channel, or the electrode-channel interface. However, because R nl is ~3 orders of magnitude smaller than the device resistance, it is possible that some charge current flows through a tortuous path from F3to F4 and F5. We investigate this by measuring the gate voltage and temperature dependence of R nl . Figure 3a shows the gate voltage dependence of R nl in the parallel and antiparallel state, R nl,p and R nl,ap , as well as their average value. Figure 3b shows the non-local spinvalve signal ΔR. R avg , R nl,p and R nl,ap all show a peak near the CNP (10 V < V g < 30 V), while ΔR is near zero in this region. Well outside this region (V g < -20 or V g > 40 V), R nl,p and R nl,ap have nearly equal magnitude and opposite sign (R avg is near zero) and ΔR is larger and shows quasi-periodic oscillations with V g . The peak in R avg (V g ) near the CNP suggests that charge current does flow in the region between F3 and F4 for these gate voltages. However, R avg (V g ) is not simply proportional to ρ(V g ) but rather drops to near zero at large V g while ρ(V g ) remains finite. Thus the finite R avg (V g ) near the CNP is likely due to the inhomogenous nature of graphene near the CNP 21,22 ; here percolating electron and hole regions may cause a tortuous current path.Away from the CNP, R avg (V g ) drops to near zero, indicating small charge current.Yet R nl,p and R nl,ap remain finite, with near equal magnitude and opposite sign. This is as 4 expected for a pure spin current flowing from F3 to F4, and cannot be explained by a magnetoresistive signal arising from any charge current between F4 and F5. The Hall effect is another possible source of V nl , however, the Hall voltage would be expected to grow large and switch sign near the CNP, rather than showing a peak. Figure 4 shows the temperature dependence of R avg and ΔR for V g = 0. Here R avg is finite similar to Figure 3, but somewhat larger for this electrode configuration. The spin-valve signal ΔR is seen to drop with temperature approximately as ΔR ∝ T -1 , while R avg is much more weakly temperature dependent; again indicating a different origin for ΔR and R avg . The inset shows a measurement at 300 K performed at higher current; the spin-valve signal can still be observed, confirming expectations of reduced spin scattering in graphene even to high temperature.We now discuss the magnitude of the spin-valve signal ΔR. For an Ohmicallycontacted spin-valve device, the non-local signal may be estimated using Eqn. 22 of reference [17]; we estimate in this case the signal should be on order 10 -5 Ω. However, we observe finite contact resistance of order 10 kΩ per electrode as estimated from the difference between two-probe and four-probe resistance measurements. In the limit of...

show abstract

“…, where R nt is the radius of the MWNT [21]. For a radius R nt = 2.7 nm, the subband spacing amounts to ∼180 meV.…”

Section: Multichannel Casementioning

confidence: 99%

Nanospintronics with carbon nanotubes

Cottet

Kontos

Sahoo

et al. 2006

Semicond. Sci. Technol.

111

127

View full text Add to dashboard Cite

One of the actual challenges of spintronics is the realization of a spin transistor allowing control of spin transport through an electrostatic gate. In this paper, we report on different experiments which demonstrate gate control of spin transport in a carbon nanotube connected to ferromagnetic leads. We also discuss some theoretical approaches which can be used to analyse spin transport in these systems. We emphasize the roles of the gate-tunable quasi-bound states inside the nanotube and the coherent spin-dependent scattering at the interfaces between the nanotube and its ferromagnetic contacts.

show abstract

Rashba spin–orbit coupling and spin precession in carbon nanotubes

Cited by 17 publications

References 32 publications

Spin–Orbit Interaction in Single Wall Carbon Nanotubes: Symmetry Adapted Tight-Binding Calculation and Effective Model Analysis

Spin–Orbit Interaction in Single Wall Carbon Nanotubes: Symmetry Adapted Tight-Binding Calculation and Effective Model Analysis

Gate-tunable graphene spin valve

Nanospintronics with carbon nanotubes

Contact Info

Product

Resources

About