Relaxation of stress-split orthoexcitons in Cu2O

초록

By applying Hertzian stress fields up to 1.1 kbar along a (100) direction we break the cubic crystal symmetry of a cuprite crystal causing the triply degenerate orthoexciton level to split into a singlet and doublet. The interconversion rate between the singlet and lower-lying doublet is measured as a function of stress at T=2 K by using subnanosecond time-resolved luminescence. Based on the experimentally observed stress dependence, we propose that this transition occurs via exciton and TA-phonon scattering associated with the off-diagonal shear tensor field (abbreviated "shear scattering"), in contrast to the axial vector field scattering (abbreviated "rotational scattering") mechanism for the ortho-para conversion.

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