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arXiv · 2107.03192

A hole-Cr$^{+}$ nano-magnet in a semiconductor quantum dot

V. Tiwari·M. Arino·S. Gupta·M. Morita·T. Inoue·D. Caliste·P. Pochet·H. Boukari·S. Kuroda·L. Besombes
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Abstract

We study a new diluted magnetic semiconductor system based on the spin of the ionized acceptor Cr$^+$. We show that the negatively charged Cr$^+$ ion, an excited state of the Cr in II-VI semiconductor, can be stable when inserted in a CdTe quantum dot (QD). The Cr$^+$ attracts a heavy-hole in the QD and form a stable hole-Cr$^+$ complex. Optical probing of this system reveals a ferromagnetic coupling between heavy-holes and Cr$^+$ spins. At low temperature, the thermalization on the ground state of the hole-Cr$^+$ system with parallel spins prevents the optical recombination of the excess electron on the 3$d$ shell of the atom. We study the dynamics of the nano-magnet formed by the hole-Cr$^+$ exchange interaction. The ferromagnetic ground states with M$_z$=$\pm$4 can be controlled by resonant optical pumping and a spin relaxation time in the 20 $μ$s range is obtained at T=4.2 K. This spin memory at zero magnetic field is limited by the interaction with phonons.

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V. Tiwari, M. Arino, S. Gupta, M. Morita, T. Inoue, D. Caliste, P. Pochet, H. Boukari, S. Kuroda, L. Besombes. 2021-07-28. A hole-Cr$^{+}$ nano-magnet in a semiconductor quantum dot. https://doi.org/10.1103/physrevb.104.l041301

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