Regensburg 2013 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 41: Spintronics / Quantum Information: Materials and Methods (jointly with HL)

TT 41.5: Talk

Wednesday, March 13, 2013, 16:00–16:15, H2

Magneto-optical study of the sp-d exchange interaction on 1.4 nm diameter Mn²⁺ doped (CdSe)₁₃ clusters — Rachel Fainblat¹, •Dino Iavarone¹, Jiwoong Yang², Taeghwan Hyeon², and Gerd Bacher¹ — ¹Werkstoffe der Elektrotechnik and CeNIDE, Universität Duisburg-Essen, Germany — ²Nanomaterials Laboratory, Seoul National University, Korea

Magnetical doping of chemically synthesized nanostructures combines the optical and electronic properties of the host semiconductor with the magnetic characteristics of the doping ions. The mechanism of colloidal nanocrystal doping can be classified into doping at the "growth" or at the "cluster" stage and, in particular, the doping efficiency in small nanocrystals is controversially discussed. On one hand, the statistical adsorption of an impurity is expected to decrease with decreasing nanocrystal size [1], whereas a recent model points out that the dopant adsorption onto the sites of small clusters (d < 2 nm) is more efficient than the adsorption on larger nanocrystals (d > 5 nm) [2].

Here, we report on low temperature (T = 5 K) magneto-optical effects in so-called "magic size" Mn²⁺ doped (CdSe)₁₃ clusters. Both absorption and magnetic circular dichroism (MCD) spectra are dominated by a resonance peak related to the heavy hole excitonic transition at 3.65 eV. From the pronounced MCD signal a giant Zeeman splitting of about 15 meV at 1.5 T is extracted supporting the theory that the Mn²⁺ ions are doped directly into the (CdSe)₁₃ clusters.

[1] S. Erwin et al., Nature 436, 91-4 (2005)

[2] T. Singh et al., Appl. Phys. Lett. 100, 053105 (2012)