Interlevel hybridization phenomena in the coincidence effect under quantum Hall regime in a HgTe quantum well

Abstract

As found from quantum magnetotransport under tilted magnetic fields in a (013)-oriented n-Cd0.7Hg0.3Te/HgTe/Cd0.7Hg0.3Te quantum well of ∼20nm width, the positions of magnetic level coincidences agree quite well with a traditional description of the coincidence effect like in a simple Γ6 band in spite of the Γ8 character of the conduction band in HgTe. The coincidence angles yield the effective g-factor g* = 33 while g* = 50÷60 is obtained with different magnetotransport techniques under fields oriented perpendicular to the layers. The difference is settled when assuming the g-factor anisotropy of g⊥/g||≈ 2. Level anticrossings are revealed at high values of perpendicular magnetic fields, corresponding to the quantum Hall regime. They manifest themselves in a splitting of the coincidence magnetoresistivity peaks and in a shift of the split-off peaks from the integer filling factors ν to the neighbouring half-integer filling factors. The anticrossing at ν = 3 is found to be significantly stronger than the neighbouring ones at ν = 2 and ν = 4 that is tentatively explained in terms of formation of easy-axis quantum Hall ferromagnetic states in the vicinity of the expected crossings.