Abstract
Magneto-reflectance of the direct excitons in InI and InBr is investigated in magnetic fields up to 15T at LHeT. Oscillatory structure which corresponds to the ns exciton states appears in magnetic fields in both halides. Their exciton energies are characterized by a hydrogenic exciton series in spite of the strongly anisotropic media. The binding energy of the exciton is determined as 4.2 meV, the reduced mass as 0.17m0 and the dielectric constant effective to the exciton binding as 24 in InI. They are 11.6 meV, 0.26m0 and 18 in InBr. In InI, the energy of the ns exciton state in the low field connects smoothly to that of the N=n−2 Landau-like state in the high field region. Moreover, in InI, the oscillatory structure is accompanied by a subsidiary peak on the high energy side in high fields.
