Figure 2: Field dependence of Si:P Lyman series.
From: Si:P as a laboratory analogue for hydrogen on high magnetic field white dwarf stars
The field was oriented along the [001] crystal axis in Faraday geometry (that is, light propagation along the field axis). The sample temperature was 2.2 K (so that kBT=0.010 Rydberg, equivalent to 1,600 K for free hydrogen atoms). (a) Experimental far-infrared absorption spectra. Each transmission spectrum has been normalized, then inverted and finally offset so that the baseline corresponds to the field applied. No smoothing or other processing has been used. The noise feature just below 50 meV that increases in size with field is due to vibrations in the magnet cooling water system. (b) Theoretical donor Lyman transition spectrum. The strongest transitions are labelled according to their upper state. The magnitude of the dipole matrix element and polarization are indicated, respectively, by the thickness and colour of the lines (red, circular σ+ for valleys 1 and 2; blue, circular σ– for valleys 1 and 2; cyan, unpolarized transitions for valleys 3–6). Some important states have been identified from the dominant components of the wavefunction character. Note that the 4f– state labelled at about 20 T is only weakly allowed and undergoes many anti-crossings with the p– series. (c) Circularly polarized absorption spectrum. (d) The multi-valley conduction band of silicon. The valley axis coordinate system (x,y,z) and the light propagation (k) and field (B) directions used are indicated.
