Figure 1

(Color online) (a) Spin susceptibility ${\chi }_{m,0}$ (in units of $\hslash /\text{eV}$) as a function of the excitation frequency $\omega$ (in terahertz) for a (4,4) NT. The distance between site $m$ and the impurity is $x_m=3a_0$. Inset shows NT with a single magnetic impurity. Arrow represents where the electrons spin is probed. (b) Solid and dashed lines represent the $\widehat{x}$ and $\widehat{y}$ components of the spin disturbance $S_m^{+}\left(t\right)$; the thick solid line depicts $\left|S_m^{+}\left(t\right)\right|$. Spins are in units of $\hslash g{\mu }_B{h}_0$, where $g$ is the electron spin $g$ factor, ${\mu }_B$ is the Bohr magneton, and $h_0$ is the amplitude of the applied time-dependent transverse field; time is given in picosecond. Results were generated with a Gaussian pulse centered at frequency $\omega =0.6\text{THz}$ and with a standard deviation $\sigma =20.7\text{ps}$.Reuse & Permissions

Figure 2

(Color online) Amplitude of the transverse spin disturbance (in units of $\hslash g{\mu }_B{h}_0$) as a function of time (in picosecond) at different distances $x_m$ from the magnetic impurity. The curves labeled from (1) to (6) represent signals probed at different values of $x_m=0.3$, 1.5, 3, 6, 9, and $12\times {10}^4{a}_0$, respectively. Inset plots how the corresponding probing positions $x_m$ relate with the time $\tau$ taken to reach a maximum spin disturbance.Reuse & Permissions

Figure 3

(Color online) Left axis depicts maximum amplitude of the pulsed excitation ${\left|⟨S_m⟩\right|}_{\text{max}}$ (in units of $\hslash g{\mu }_B{h}_0$) probed at site $m$ and is shown by the solid line with circular symbols. Right axis represents the width $\Delta$ (in picosecond) of the probed pulses shown by dashed lines with square symbols. Both quantities are plotted as a function of the separation $x_m$ (in units of $a_0$) from the impurity location. Panels (a) and (b) are for pulses centered at resonance and off-resonance frequencies, respectively.Reuse & Permissions

Figure 4

(Color online) Amplitude of the pulsed excitation as a function of time (in picoseconds) for the case of two magnetic impurities a long distance apart $\left(x_m=6\times {10}^4{a}_0\right)$. Solid line shows the spin disturbance evaluated at the impurity where the excitation is induced whereas the dashed line is evaluated at the other impurity location.Reuse & Permissions