Dominant Mechanism for Spin Relaxation and Spin Decoherence of Transition-Metal-Ion Spin Centers in Halide Double Perovskites

High Resolution Image Download MS PowerPoint Slide Spin-active centers in solid-state hosts with long spin relaxation ( T 1 ) and coherence ( T 2 ) times are emerging as excellent candidates for both classic and quantum spintronic applications. Here, we investigate temperature-dependent spin relaxation and decoherence of Cr 3+ and Fe 3+ centers in the double perovskite Cs 2 NaInCl 6 host, aiming to both provide a fundamental understanding of the role of phonons in spin relaxation and decoherence and identify the potential of these transition-metal ions for spin-based technologies. Pulsed electron spin resonance studies reveal that electron spin relaxation of these centers is primarily driven by a spin-phonon interaction between electron spins and low-frequency nondispersive phonon modes, which are due to local motion of Cs and Cl atoms. This spin-phonon interaction also severely limits spin coherence properties, leading to an acceleration of spin decoherence at temperatures above 20 K, while the spin decoherence below 20 K is currently limited by electron spin flip-flop noise due to a high concentration of spin centers. We anticipate that a key strategy for achieving high-temperature quantum spin operation is to increase the frequency of these lower-lying phonon modes by replacing Cs with lighter atoms.