Long-lived selective spin echoes in dipolar solids under periodic and aperiodic pi-pulse trains

Abstract

The application of Carr-Purcell-Meiboom-Gill (CPMG) $\pi -$trains for dynamically decoupling a system from its environment has been extensively studied in a variety of physical systems. When applied to dipolar solids, recent experiments have demonstrated that CPMG pulse trains can generate long-lived spin echoes. While there still remains some controversy as to the origins of these long-lived spin echoes under the CPMG sequence, there is a general agreement that pulse errors during the $\pi -$pulses are a necessary requirement. In this work, we develop a theory to describe the spin dynamics in dipolar coupled spin-1/2 system under a CPMG(${\varphi }_1,{\varphi }_2$) pulse train, where ${\varphi }_1$ and ${\varphi }_2$ are the phases of the $\pi -$pulses. From our theoretical framework, the propagator for the CPMG(${\varphi }_1,{\varphi }_2$) pulse train is equivalent to an effective ``pulsed'' spin-locking of single-quantum coherences with phase $\pm \frac{{\varphi }_2-3{\varphi }_1}{2}$, which generates a periodic quasiequilibrium that corresponds to the long-lived echoes. Numerical simulations, along with experiments on both magnetically dilute, random spin networks found in C${}_{60}$ and C${}_{70}$ and in non-dilute spin systems found in adamantane and ferrocene, were performed and confirm the predictions from the proposed theory.

25 pages, 12 figures, submitted to Physical Review B

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Cited by in corpus (2)

• Locking of electron spin coherence over fifty milliseconds in natural silicon carbide
• Dynamical suppression of fluctuations in an interacting nuclear spin bath of a self-assembled quantum dot using multiple pulse nuclear magnetic resonance