Electron spin relaxation in semiconducting carbon nanotubes: the role of hyperfine interaction

The long standing problem of inexplicably short spin relaxation in carbon nanotubes (CNTs) is examined. The curvature-mediated spin-orbital interaction is shown to induce fluctuating electron spin precession causing efficient relaxation in a manner analogous to the Dyakonov-Perel mechanism. Our calculation estimates longitudinal (spin-flip) and transversal (decoherence) relaxation times as short as 150 ps and 110 ps at room temperature, respectively, along with a pronounced a...

This work considers the g-tensor anisotropy induced by the flexural thermal vibrations in one-dimensional structures and its role in electron spin relaxation. In particular, the mechanism of spin-lattice relaxation via flexural modes is studied theoretically for localized and delocalized electronic states in semiconducting carbon nanotubes in the presence of magnetic field. The calculation of one-phonon spin-flip process predicts distinctive dependencies of the relaxation rat...

We analytically calculate the nuclear-spin interactions of a single electron confined to a carbon nanotube or graphene quantum dot. While the conduction-band states in graphene are p-type, the accordant states in a carbon nanotube are sp-hybridized due to curvature. This leads to an interesting interplay between isotropic and anisotropic hyperfine interactions. By using only analytical methods, we are able to show how the interaction strength depends on important physical par...

We use charge sensing of Pauli blockade (including spin and isospin) in a two-electron 13C nanotube double quantum dot to measure relaxation and dephasing times. The relaxation time, T1, first decreases with parallel magnetic field then goes through a minimum in a field of 1.4 T. We attribute both results to the spin-orbit-modified electronic spectrum of carbon nanotubes, which suppresses hyperfine mediated relaxation and enhances relaxation due to soft phonons. The inhomogen...

We have studied theoretically the electron spin relaxation in semiconductor quantum dots via interaction with nuclear spins. The relaxation is shown to be determined by three processes: (i) -- the precession of the electron spin in the hyperfine field of the frozen fluctuation of the nuclear spins; (ii) -- the precession of the nuclear spins in the hyperfine field of the electron; and (iii) -- the precession of the nuclear spin in the dipole field of its nuclear neighbors. In...

Single wall carbon nanotubes grown entirely from 13-C form an ideal system to study the effect of electron interaction on nuclear magnetism in one dimension. If the electrons are in the metallic, Luttinger liquid regime, we show that even a very weak hyperfine coupling to the 13-C nuclear spins has a striking effect: The system is driven into an ordered phase, which combines electron and nuclear degrees of freedom, and which persists up into the millikelvin range. In this pha...

We report on the spin dynamics of 13C isotope enriched inner-walls in double-wall carbon nanotubes (DWCNT) using 13C nuclear magnetic resonance (NMR). Contrary to expectations, we find that our data set implies that the spin-lattice relaxation time (T1) has the same temperature (T) and magnetic field (H) dependence for most of the innerwall nanotubes detected by NMR. In the high temperature regime (T > 150 K), we find that the T and H dependence of 1/T1T is consistent with a ...

Recent transport measurements [Churchill \textit{et al.} Nat. Phys. \textbf{5}, 321 (2009)] found a surprisingly large, 2-3 orders of magnitude larger than usual $^{13}$C hyperfine coupling (HFC) in $^{13}$C enriched single-wall carbon nanotubes (SWCNTs). We formulate the theory of the nuclear relaxation time in the framework of the Tomonaga-Luttinger liquid theory to enable the determination of the HFC from recent data by Ihara \textit{et al.} [Ihara \textit{et al.} EPL \tex...

For coherent electron spins, hyperfine coupling to nuclei in the host material can either be a dominant source of unwanted spin decoherence or, if controlled effectively, a resource allowing storage and retrieval of quantum information. To investigate the effect of a controllable nuclear environment on the evolution of confined electron spins, we have fabricated and measured gate-defined double quantum dots with integrated charge sensors made from single-walled carbon nanotub...

We have measured temperature ($T$)- and power-dependent electron spin resonance in bulk single-wall carbon nanotubes to determine both the spin-lattice and spin-spin relaxation times, $T_1$ and $T_2$. We observe that $T_1^{-1}$ increases linearly with $T$ from 4 to 100 K, whereas $T_2^{-1}$ {\em decreases} by over a factor of two when $T$ is increased from 3 to 300 K. We interpret the $T_1^{-1} \propto T$ trend as spin-lattice relaxation via interaction with conduction electr...