Materials scientists would very much like to be able to incorporate paramagnetic ions into semiconductor quantum dots (QDs) with a view to more finely controlling the properties of such entities as well as opening up novel applications.

Geoffrey Strouse, Florida State University, Tallahassee, USA, and colleagues have now obtained the first evidence of inclusion of a stable spinel, ZnCr₂Se₄, at the core of a chromium-doped zinc selenide QD. The team used X-ray absorption near edge spectroscopy (XANES), crystal field absorption spectroscopy, and electron paramagnetic resonance (EPR) spectroscopy and showed that the inclusion of the spinel is akin to the formation of a spinel phase within conventional crystals of chromium zinc selenide.

The material represents a new class of dilute magnetic semiconductor QDs for further research.

• Evidence of a ZnCr2Se4 Spinel Inclusion at the Core of a Cr-Doped ZnSe Quantum Dot,
  W. Zheng, K. Singh, Z. Wang, J. T. Wright, J. van Tol, N. S. Dalal, R. W. Meulenberg, G. F. Strouse,
  J. Am. Chem. Soc. 2012.
  DOI: 10.1021/ja210285p