Magnetic and non-magnetic Faraday rotation in ZnMnSe in high magnetic fields

Abstract

Faraday rotation (FR) spectra over a wide photon energy range were measured in Zn 0.985 Mn 0.015 Se by a streak spectrometer using a CCD detector in high magnetic fields. The spectra obtained in the experiment showed a number of unique features. The FR is a rapidly increasing function of field in the low field range, but, above a certain critical field, it starts decreasing linearly, showing a clear turn-around. The turn-around is well explained in terms of the competition between the paramagnetic and the diamagnetic components of the Faraday rotation in high magnetic fields. This is the first observation of the reversal of the field coefficient of the FR in diluted magnetic semiconductors.

Absorption and Magnetic Circular Dichroism Analyses of Giant Zeeman Splittings in Diffusion-Doped Colloidal Cd1–xMnxSe Quantum Dots

“…One promising approach involves embedding magnetic impurity ions within such nanostructures. Magnetic exchange interactions between these localized magnetic impurities and delocalized semiconductor charge carriers give rise to the so-called “giant” Zeeman splittings of the semiconductor band structure. − Such splittings in turn impart extraordinary magnetic, magneto-optical, and magneto-electronic properties to this class of materials, including “giant” Faraday rotation effects, − carrier-controlled magnetism, − carrier or exciton spin polarization, − single- or few-impurity exchange-split excitons, − and spontaneous photoinduced magnetization at zero applied field (excitonic magnetic polarons). − …”

Thermal Tuning and Inversion of Excitonic Zeeman Splittings in Colloidal Doped CdSe Quantum Dots

“…These splittings lend DMSs a variety of extraordinary magnetic, magneto-optical, and magneto-transport properties that make them attractive for semiconductor-based spintronics or spin-photonics technologies . Giant Zeeman splittings of excitons give rise to the so-called giant Faraday rotation effect, − useful in Faraday optical isolators, and to spin-polarized excitonic photoluminescence, in which magnetic fields control luminescence polarizations. Giant Zeeman splittings are also responsible for the spontaneous zero-field magnetization observed in excitonic magnetic polarons. − …”

“…Similarly, eq 1 predicts that at fixed temperature, the g value can be inverted by application of a magnetic field. Whereas inversion of DMS spin splittings has indeed been demonstrated at cryogenic temperatures using large magnetic fields and low dopant concentrations, ,,, the use of temperature for this purpose has not been explored.…”