Zeeman effect on the excitonic reflection spectrum of CuCl at very low temperatures

The influence of an external magnetic field on the normal incidence reflectivity of CuCl single crystals has been measured in the Voigt and Faraday configurations. The resulta ore discussed in terms of the dielectric function calculated from the reflectivity spectrum by a Kramers-Kronig transformation. In the Voigt configuration two new exciton bands can be observed, which are attributed to a triplet and a longitudinal exciton. Their energetic positions are used to determine the parameters of electron-hole exchange interaction in the 1s excitons, and the spin-orbit splitting parameter of the upper valence band. The excitonic g-values are determined from the Faraday configuration measurements and can be interpreted on the basis of the tight binding model.

Section: Introductionmentioning

confidence: 80%

Magneto‐Reflectivity Measurements on Exciton Bands in CuCl

Staude

1971

“…Different effects may lift the energetic degeneracy. I n CuC1, however, the electron-hole exchange interaction is particiilarly important, as it is known from the study of the free-exciton spectra [19,201, and plays probably the most important part. I n our high-purity samples, the impurity concentration is certainly very low, so that there is no appreciable overlapping between the different impurity centres.…”

Section: Discussionmentioning

confidence: 99%

Acceptor Bound Exciton States in High‐Purity CuCl

Sauder

Stébé

Certier

1981

Self Cite

The magneto-optical properties of high-purity CuCl at 4.2 K show that the two lines vi (25665.2 cm-l) and v i (25697.6 em-l) are due t o transitions to (or from) excitons bound to the same neutral acceptor, the two holes arising from the lowest rs valence band. They are attributed, respectively, to the J = 512 and J = 112 states of the (Ao, X) complex. These results are explained by the importance of the electron-hole exchange interaction and by a dominant occurrence of the rS rather than the r7 neutral acceptors. As a consequence, free holes should chiefly arise from the I?, valence band. This is due to the particularly low value of the valence band spin-orbit splitting ( A s 0 z 600 cm-l), compared to the free-exciton binding energy (Ex z 1523 em-l) or to the estimated r7 acceptor ionization energy (Ex =: 17000 cm-l). These conclusions support, the previous assignment of line v2 (25654 cm-l) to a transition between a free r, hole and a ra charged exciton Xz+.

“…Due to the spin structure the excitons of intermediate and small radii are rather He-like formations than H-like ones. The experimental separation of ortho-and paraexcitonic states in a CaCl crystal is 50 cm-1 [8]. Estimations for the n = 1 exciton levels in the Cu,O crystal show that the exchange interaction in the exciton is of the order of 40 cm-1 191.…”

mentioning

confidence: 90%

The Change of Sound Velocity at the Bose‐Einstein Condensation of Excitons in Crystals

Miglei¹,

Moskalenko²,

Lelyakov³

1969

Belyaev's equations are generalized for the case of a non-ideal gas of excitons interacting with the phonons in the crystal at T = 0. In the first approximation of the perturbation theory the energetic spectrum of the elementary excitations is received. The change of sound velocity in some crystals is calculated for different assumptions with reference to the constants of exciton-exciton and exciton-phonon interactions.YpaBHeHacI BencIeBa 0606we~b1 Ha caysat Hemeanmoro ra3a ~KCIITOHOB B3aHMO@kTByIOlHX C 4OHOHBMH B KpHCTaJIJIe IIpH T = 0. n0nyYeH 3HepreTH-W X K I I d CIIeIETp 3JIeMeHTapHbIX BO36ymAeHHa. kI3MeHeHHe CKOPOCTH 3ByHa B He-KOTOpbIX KpIICTaJIaaX paCC4HTaHO HJIII pa3JIHsHbIX IIpe~llOJIO%eHIIfi OTHOCHTeJIbHO IiOHCTaHT 3KCIITOH-3KCIITOHHOI'O H 3KCHTOH-l$OHOHHOrO B3aHMOJXefiCTBHG.