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Tailoring Magnetism in Bulk Semiconductors and Quantum Dots


Carrier-mediated magnetism in bulk-like semiconductors reveals intriguing opportunities to control magnetic ordering. For example, the change in carrier density induced by light or bias could be sufficient to turn the ferromagnetism on and off .  We propose that ferromagnetism can also be induced by raising the temperature [1]. This unexpected reentrant ferromagnetic phase is thermodynamically stable and we provide experimental support for its existence. We also examine magnetically doped quantum dots in which the interplay of quantum confinement and strong Coulomb interactions can lead to novel possibilities to tailor magnetism.  Even at the fixed number of carriers, the gate induced changes in the screening [2] or deviations from isotropic quantum confinement [3] could allow for a reversible control of magnetism and switching between zero and finite magnetization. Recent experiments on magnetic polarons [4] reveal theoretical challenges in describing magnetic quantum dots and suggest that a versatile control of magnetism in these systems could be feasible at room temperature.

[1] A. G. Petukhov, I. Zutic, and S. Erwin, Phys. Rev. Lett. 99 , 257202 (2007)

[2] R. M. Abolfath, P. Hawrylak, and I. Zutic, Phys. Rev. Lett. 98 , 207203 (2007).

[3] R. M. Abolfath, A. G. Petukhov, and I. Zutic, Phys. Rev. Lett. 101 , 207202 (2008).

[4] R. Beaulac et al., Science 325 , 973 (2009); S. T. Ochsenbein et al., Nature Nanotech.

4, 681 (2009); I. Zutic and A. G. Petukhov, Nature  Nanotech. 4, 623 (2009); I. R.

Sellers et al., arXiv:0912.0138.