First-principles study of spin transport in $$\hbox {CrO}_{2}\hbox {-SiCNT-CrO}_{2}$$ CrO 2 -SiCNT-CrO 2 magnetic tunnel junction

Abstract

We report the spin transport in silicon carbide nanotube based magnetic tunnel junction with half-metallicferromagnet CrO 2 as electrodes. The simulations based on first principles suggest high tunnel magnetoresistance ∼100 % at zero bias, TMR remains high at higher bias voltages. I-V characteristics show that spin current in parallel magnetic configuration is much higher than the spin current in anti-parallel configuration. Perfect spin-filtration effect is obtained for this structure. Transmission coefficients are also calculated to understand the spin and bias dependent nonequilibrium transport properties.

Spin Transport Properties in 1D DNA and Electrically Doped Iron Quantum Dot Organo-metallic Junction: A First Principle Paradigm

“…Electrode temperature is kept 300k to get faster convergence. For PC, the relative spin is to be set at 1/0/1 and for APC it is set to be 1/0/-1 [1]. The gap between electrode and DNA is kept minimal to achieve maximum transport current.…”

Effect of Twisting and Stretching on Magneto Resistance and Spin Filtration in CNTs

“…The self-consistent calculations are performed on the basis of DFT and NEGF formulation. For exchange-correlation, spin-polarized generalized gradient approximation (SGGA) is used, because the current is due to spin-polarized electron transport [13]; exact exchange potential of atoms is used to analyze generalized gradient approximations (GGAs) [19]. In general, spin-polarized GGA is more accurate than local-spin density approximation (LSDA) in atomic structure and energetic, but the difference between the former and the latter in terms of the electronic properties of solid-state systems is relatively small [20].…”

“…Pristine, twisted, and stretched CNTs are also shown in Figure 3. A zigzag (6, 0) twisted CNT and zigzag (6, 0) stretched CNT with a bond length of 1.421 Å between carbon atoms and length of 15.629 Å is considered in the simulations, as in [13]. The bond length between carbon and chromium is kept at ~2.09 Å [13].…”

“…The mesh cutoff and electron temperature are assumed to be 150 Ry and 1800 K, respectively. The k point sampling in x, y, and z directions are assumed to be 3, 3, 100, respectively, as in [13]. In the simulations, magnetization of the electrodes can be simply changed to either up or down by assuming 1 or −1 spin polarization values.…”

“…It is therefore of interest to use (6, 0) CNT and understand how twisting or stretching of CNT affect its spin transport properties. The quantum transport properties of pristine CNT are reported in [13]. It is understood that during the fabrication process some defects may occur in CNTs.…”