Muonium as a probe of electron spin polarisation in CdTe

• Published in: Physica. B, Condensed matter Vol. 404; no. 23-24; pp. 5110 - 5112
• Main Authors: Alberto, H.V., Weidinger, A., Vilão, Rui, Piroto Duarte, J., Gil, J.M., Ayres de Campos, N., Lord, J.S., Cox, S.F.J.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.12.2009
• Subjects: Electron spin polarisation; II–VI semiconductors; Muonium; Electron spin polarisation; Muonium; II–VI semiconductors
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/j.physb.2009.08.244

Muonium, consisting of a positive muon and an electron, is a pseudo-isotope of hydrogen. Muon spin rotation (μSR) experiments with CdTe single crystals, nominally undoped, were performed at Paul Scherer Institut, in Switzerland, at 0.02 and 0.05K and under an external transverse magnetic field up to 2T. A weakly bound muonium state is formed in CdTe with a very small hyperfine interaction (near 260kHz). The frequency spectra show two muonium lines corresponding to different electron spin states (up and down) which have different energies in the presence of a magnetic field. The normalised intensity difference of muonium lines was used as a measure of the spin polarisation of the electrons captured by the muon. The electron spin polarisation in the muonium atom was found to be considerably lower than expected for a population in thermodynamical equilibrium; the data can be described by a modified Brillouin function with a saturation value which was found to change with the sample age.