Spin-valley

Fig. 6.5. Absorption spectrum from the Is excited states of Sb donors in silicon, showing the spin-valley splitting of the ls(T2) state, observed by raising the temperature of the sample to 30K. The lowest energy line of the Is (Ai) spectrum is at 31.24meV (251.9cm-1). The spectral range is 145.2-243.6cm-1. [Sb] is 2.6 x l()lr crri 3 [163]. Copyright 1993 by the American Physical Society...

Some lines associated with the deepest donor excited states of the S2+ and Se2+ pairs and of ScXi+ and SecXi+ have also been observed and their positions are given in Table6.19. By analogy with the ls(T2) state of the Ch+ donors, the 1 s (E-) state of the Ch.j donors with />j(j symmetry can be assumed to be split by spin-valley interaction into 1 sly and 1 sTg, where IV, and T are single-valued IRs of the double group of Dm. In Table 6.19, the two first low-energy lines of S2"1" and Se2+ are labelled accordingly. 

When the QD levels deviate from the Fermi surface, as shown in Fig. 2c and 2d with b = r/2, an interesting result is that Gm. and Gdl do not vary with in phase. When (f) = 7t, the peak of one conductance Ggi or God just encounters the valley of another one. In Fig. 2e and 2f, when

spin polarization. Importantly, in such a case Gri o and G g almost... 

The line connecting the zero level with any vertex of the subsequent levels is called the line of structure realization or the valley (as adopted in the theory of spin glasses [6.77]). The vertices lying along the valley show the structure states of the microcluster and the cluster core. 

The Ch-related donor spectra differ on that point as several parity-forbidden transitions are observed. They start with symmetry-allowed transitions from the Is ground state to the valley-orbit split Is excited states, and are supplemented with 2s (T2) and 3s (T2) lines and Fano resonances within the photoionization spectrum. This is shown in Fig. 6.13 for Se°. Compared to group-V donors, this extends the energy span of the Ch°-related spectra to the ionization energy of the Is (T2) level (35-40 meV in isolated chalcogens) and it can even increase to 40-48 meV when singlet-triplet spin-forbidden transitions are observed. 

Three important conclusions emerge from this analysis. First of all, all INDOR responses induced by this particular mechanism will be in the negative direction, as they eifectively correspond to the trace of the valley between a pair of spin-tickled transitions. The second, and more important, conclusion is that INDOR responses will only be induced at frequencies corresponding to transitions that are spin-coupled to the transition that is being monitored no other transitions can induce INDOR responses. Thus, as the third conclusion, the INDOR experiment can be used to detect transitions that are entirely obscured by other overlapping transitions. ... 

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