Limits...
Noise and fluctuation relations of a spin diode.

Lim JS, López R, Sánchez D - Nanoscale Res Lett (2013)

Bottom Line: We investigate a prototypical spintronic device - a spin-diode - which consists of an interacting resonant level coupled to two ferromagnetic electrodes.We thereby obtain the cumulant generating function for the spin transport in the sequential tunnelling regime.We demonstrate the fulfilment of the nonlinear fluctuation relations when up and down spin currents are correlated in the presence of both spin-flip processes and external magnetic fields.

View Article: PubMed Central - HTML - PubMed

Affiliation: Instituto de Física Interdisciplinar y Sistemas Complejos IFISC (UIB-CSIC), Palma de Mallorca E-07122, Spain. lim.jongsoo@gmail.com.

ABSTRACT
: We consider fluctuation relations between the transport coefficients of a spintronic system where magnetic interactions play a crucial role. We investigate a prototypical spintronic device - a spin-diode - which consists of an interacting resonant level coupled to two ferromagnetic electrodes. We thereby obtain the cumulant generating function for the spin transport in the sequential tunnelling regime. We demonstrate the fulfilment of the nonlinear fluctuation relations when up and down spin currents are correlated in the presence of both spin-flip processes and external magnetic fields.

No MeSH data available.


Related in: MedlinePlus

Sketches of the spin diode system and electrostatic model. (a) Sketch of the spin diode system. The dot level is attached to two ferromagnetic contacts. VLσ and VRσ indicate the spin-dependent bias voltages applied to the left (L) and (R) right contacts, respectively. The dot level is spin split by a magnetic field B: ε↑≠ε↓. Both spin-dependent energy levels are connected by spin-flip processes with a rate given by γsf. (b) Electrostatic model: ϕ↑, and ϕ↓ are the dot internal potentials calculated using capacitance couplings [ Cui, Cdi (i=1⋯4), C] within an electrostatic model.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3686707&req=5

Figure 1: Sketches of the spin diode system and electrostatic model. (a) Sketch of the spin diode system. The dot level is attached to two ferromagnetic contacts. VLσ and VRσ indicate the spin-dependent bias voltages applied to the left (L) and (R) right contacts, respectively. The dot level is spin split by a magnetic field B: ε↑≠ε↓. Both spin-dependent energy levels are connected by spin-flip processes with a rate given by γsf. (b) Electrostatic model: ϕ↑, and ϕ↓ are the dot internal potentials calculated using capacitance couplings [ Cui, Cdi (i=1⋯4), C] within an electrostatic model.

Mentions: Consider a quantum dot coupled via tunnel barriers to two ferromagnetic leads α=L,R, as shown in Figure 1a. The leads have spin-dependent density of states ρα↑(ω)≠ρα↓(ω) (flat density of states are depicted in Figure 1a). For convenience, we introduce the leads’ spin polarization parameter as pα=(ρα↑−ρα↓)/(ρα↑+ρα↓). In the limit of (Δε is the dot level spacing, kB is the Boltzmann constant, and T is the temperature) effectively only a single energy level εσ (σ=↑,↓) in the dot contributes to the transport and can be occupied by 0, 1, or 2 electron charges. In the presence of an external magnetic field B, the Zeeman splitting is ε↑−ε↓=gμBB (g is the Landé factor and is the Bohr magneton, with q as the electron charge). Tunneling between lead α and the dot yields a level broadening given by Γασ(ω)=Πρασ/Vα/2 (Vα is the lead-dot tunneling amplitude). Notice that the level width is then spin-dependent due to the spin asymmetry of the density of states: Γασ=(Γ/2)(1+spα), with Γ=ΓL=ΓR and s=+(−) for ↑(↓).


Noise and fluctuation relations of a spin diode.

Lim JS, López R, Sánchez D - Nanoscale Res Lett (2013)

Sketches of the spin diode system and electrostatic model. (a) Sketch of the spin diode system. The dot level is attached to two ferromagnetic contacts. VLσ and VRσ indicate the spin-dependent bias voltages applied to the left (L) and (R) right contacts, respectively. The dot level is spin split by a magnetic field B: ε↑≠ε↓. Both spin-dependent energy levels are connected by spin-flip processes with a rate given by γsf. (b) Electrostatic model: ϕ↑, and ϕ↓ are the dot internal potentials calculated using capacitance couplings [ Cui, Cdi (i=1⋯4), C] within an electrostatic model.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3686707&req=5

Figure 1: Sketches of the spin diode system and electrostatic model. (a) Sketch of the spin diode system. The dot level is attached to two ferromagnetic contacts. VLσ and VRσ indicate the spin-dependent bias voltages applied to the left (L) and (R) right contacts, respectively. The dot level is spin split by a magnetic field B: ε↑≠ε↓. Both spin-dependent energy levels are connected by spin-flip processes with a rate given by γsf. (b) Electrostatic model: ϕ↑, and ϕ↓ are the dot internal potentials calculated using capacitance couplings [ Cui, Cdi (i=1⋯4), C] within an electrostatic model.
Mentions: Consider a quantum dot coupled via tunnel barriers to two ferromagnetic leads α=L,R, as shown in Figure 1a. The leads have spin-dependent density of states ρα↑(ω)≠ρα↓(ω) (flat density of states are depicted in Figure 1a). For convenience, we introduce the leads’ spin polarization parameter as pα=(ρα↑−ρα↓)/(ρα↑+ρα↓). In the limit of (Δε is the dot level spacing, kB is the Boltzmann constant, and T is the temperature) effectively only a single energy level εσ (σ=↑,↓) in the dot contributes to the transport and can be occupied by 0, 1, or 2 electron charges. In the presence of an external magnetic field B, the Zeeman splitting is ε↑−ε↓=gμBB (g is the Landé factor and is the Bohr magneton, with q as the electron charge). Tunneling between lead α and the dot yields a level broadening given by Γασ(ω)=Πρασ/Vα/2 (Vα is the lead-dot tunneling amplitude). Notice that the level width is then spin-dependent due to the spin asymmetry of the density of states: Γασ=(Γ/2)(1+spα), with Γ=ΓL=ΓR and s=+(−) for ↑(↓).

Bottom Line: We investigate a prototypical spintronic device - a spin-diode - which consists of an interacting resonant level coupled to two ferromagnetic electrodes.We thereby obtain the cumulant generating function for the spin transport in the sequential tunnelling regime.We demonstrate the fulfilment of the nonlinear fluctuation relations when up and down spin currents are correlated in the presence of both spin-flip processes and external magnetic fields.

View Article: PubMed Central - HTML - PubMed

Affiliation: Instituto de Física Interdisciplinar y Sistemas Complejos IFISC (UIB-CSIC), Palma de Mallorca E-07122, Spain. lim.jongsoo@gmail.com.

ABSTRACT
: We consider fluctuation relations between the transport coefficients of a spintronic system where magnetic interactions play a crucial role. We investigate a prototypical spintronic device - a spin-diode - which consists of an interacting resonant level coupled to two ferromagnetic electrodes. We thereby obtain the cumulant generating function for the spin transport in the sequential tunnelling regime. We demonstrate the fulfilment of the nonlinear fluctuation relations when up and down spin currents are correlated in the presence of both spin-flip processes and external magnetic fields.

No MeSH data available.


Related in: MedlinePlus