Influence of nonequilibrium phonons on the spin dynamics of a single Cr atom

V. Tiwari (1) , K. Makita (2) , M. Arino (2) , M. Morita (2) , S. Kuroda (2) , H. Boukari (1) , L. Besombes (1)

1 NEEL - NPSC - Nanophysique et Semiconducteurs
2 Université de Tsukuba = University of Tsukuba

We analyse the influence of optically generated non-equilibrium phonons on the spin relaxation and effective spin temperature of an individual Cr atom inserted in a quantum dot. Using a three pulses pump-probe technique, we show that the spin relaxation measured in resonant optical pumping experiments strongly depends on the optical excitation conditions. We observe for an isolated Cr in the dark a heating time shorter than a few hundreds ns after an initial high power non-resonant excitation pulse. A cooling time larger than a few tens of µs, independent on the excitation, is obtained in the same experimental conditions. We show that a tunable spin-lattice coupling dependent on the density of non-equilibrium phonons can explain the observed dynamics. Low energy excitation conditions are found where the Cr spin states Sz=±1 can be efficiently populated by a non-resonant optical excitation, prepared and read-out by resonant optical pumping and conserved in the dark during a few µs.

Domaines: Autre [cond-mat.other]

V. Tiwari, K. Makita, M. Arino, M. Morita, S. Kuroda, et al.. Influence of nonequilibrium phonons on the spin dynamics of a single Cr atom. Physical Review B, 2020, 101 (3), pp.035305. ⟨10.1103/PhysRevB.101.035305⟩. ⟨hal-02465836⟩