Ballistic collective group delay and its Goos–Hänchen component in graphene

Song, Yu; Wu, Han

doi:10.1088/0953-8984/25/35/355301

Cited by 13 publications

(16 citation statements)

References 38 publications

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“…Note, in this space, a four-component wave function should be solved [30]. Different from them, in equation (2), we also consider a spin-resolved Fermi velocity v s .…”

Section: Calculation Formulamentioning

confidence: 99%

Electric-field-induced extremely large change in resistance in graphene ferromagnets

Song

2017

J. Phys. D: Appl. Phys.

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A colossal magnetoresistance (∼ 100 × 10 3 %) and an extremely large magnetoresistance (∼ 1 × 10 6 %) have been previously explored in manganite perovskites and Dirac materials, respectively. However, the requirement of an extremely strong magnetic field (and an extremely low temperature) makes them not applicable for realistic devices. In this work, we propose a device that can generate even larger changes in resistance in a zero-magnetic field and at a high temperature. The device is composed of a graphene under two strips of yttrium iron garnet (YIG), where two gate voltages are applied to cancel the heavy charge doping in the YIG-induced half-metallic ferromagnets. By calculations using the Landauer-Büttiker formalism, we demonstrate that, when a proper gate voltage is applied on the free ferromagnet, changes in resistance up to 305 × 10 6 % (16 × 10 3 %) can be achieved at the liquid helium (nitrogen) temperature and in a zero magnetic field. We attribute such a remarkable effect to a gate-induced full-polarization reversal in the free ferromagnet, which results in a metal-state to insulator-state transition in the device. We also find that, the proposed effect can be realized in devices using other magnetic insulators such as EuO and EuS. Our work should be helpful for developing a realistic switching device that is energy saving and CMOS-technology compatible.

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“…Note, in this space, a four-component wave function should be solved [30]. Different from them, in equation (2), we also consider a spin-resolved Fermi velocity v s .…”

Section: Calculation Formulamentioning

confidence: 99%

Electric-field-induced extremely large change in resistance in graphene ferromagnets

Song

2017

J. Phys. D: Appl. Phys.

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“…The dwell time was first introduced by Smith, which is defined as the time spent by a particle in the barrier region 0 \ x \ L [21]. Recently, some papers have focused on the group delay and/or dwell time in graphene-based barrier nanostructures [22][23][24][25][26][27][28][29][30]. In this work, we study the dwell time through an asymmetric barrier in monolayer graphene with RSOI, which to the best of our knowledge has not already been reported.…”

Section: Introductionmentioning

confidence: 97%

Rashba spin–orbit effect on dwell time in graphene asymmetrical barrier

Sattari

2014

Appl. Phys. A

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We investigated the dwell time of electrons tunneling through an asymmetric barrier in monolayer graphene with the Rashba spin-orbit interaction (RSOI). The results show that the dwell time oscillates by increasing the barrier width, RSOI strength, and the bias voltage. In addition, when an external electric field is present, the spin polarization can be observed, whereas for the RSOI alone it is zero. Furthermore, it is found that electrons with different spin orientations will spend different times through the barrier. The difference of the dwell time between spin-up and spin-down electrons arises from the Rashba spin-orbit interaction. It can be concluded that Rashba spin-orbit effect can cause a natural spin filter mechanism in the time domain.

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“…The self-interference effect arises from the overlap of incident and reflected waves at the entrance of the scattering region. Recently, the Winful relation has been generalized to systems made of graphene monolayer [13][14][15][16][17][18] or bilayer 19 . It is commonly believed that for Dirac particles in graphene, the dwell time always equals the group delay [13][14][15][16][17]19 .…”

Section: Introductionmentioning

confidence: 99%

General relation between the group delay and dwell time in multicomponent electron systems

Zhai

2016

Phys. Rev. B

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For multicomponent electron scattering states, we derive a general relation between the Wigner group delay and the Bohmian dwell time. It is found that the definition of group delay should account for the phase of the spinor wave functions of propagating modes. The difference between the group delay and dwell time comes from both the interference delay and the decaying modes. For barrier tunneling of helical electrons on a surface of topological insulators, our calculations including the trigonal-warping term show that the decaying modes can contribute greatly to the group delay. The derived relation between the group delay and the dwell time is helpful to unify the two definitions of tunneling time in a quite general situation.

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Ballistic collective group delay and its Goos–Hänchen component in graphene

Cited by 13 publications

References 38 publications

Electric-field-induced extremely large change in resistance in graphene ferromagnets

Electric-field-induced extremely large change in resistance in graphene ferromagnets

Rashba spin–orbit effect on dwell time in graphene asymmetrical barrier

General relation between the group delay and dwell time in multicomponent electron systems

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