Far-infrared observation of cyclotron and spin-flip resonances in HgSe

Abstract

Far-infrared (FIR} magnetotransmission experiments were carried out at 4.2 K on high-purity HgSe crystals, with the use of a CO2-pumped FIR laser and magnetic fields up to 14 T. Measurements were performed in the Voigt geometry, at three FIR wavelengths: 96.5, 119, and 163 p, m. In addition to the usual plasma-shifted cyclotron resonance occurring in the transverse Voigt geometry, we have observed electric-dipole-excited electron-spin-resonance (EDE-ESR} and combined-resonance transitions. These resonances are made possible by the relaxation of selection rules due to spin-orbit coupling, as a consequence of k p interaction and/or inversion asymmetry. Our data suggest that the inversion-asymmetry mechanism is stronger in HgSe than in other materials studied by FIR magnetotransmission, e.g., InSb, %e have also observed a small but unambiguous magnetoplasma shift in EDE-ESR occurring in the transverse Voigt geometry. The positions of the observed resonances at the three laser frequencies were used to obtain band-structure parameters for HgSe within the framework of the Pidgeon-Brown model.

Far-infrared spin resonance in narrow-gap semiconductors

“…Observations of SR can then only be achieved using higher FIR frequencies, which in turn require magnetic fields that are not commonly available. The first observation of EDSR in HgSe has been reported by Pastor et a1 [25], who observed a very strong resonance in the parallel Voigt geometry and interpreted this as EDSR induced by inversion asymmetry. An example of the FIR data from [25] for the Voigt geometry is shown in figure 6, where the full curve represents the data for E // B polarisation, EDSR being the line just above 7 T. The data shown by the broken curve correspond to the perpendicular Voigt geometry ( E l B), manifesting plasma-shifted EDSR which will be discussed in $4.…”

“…In studying HgSe in the transverse Voigt geometry, Pastor et a1 C251 observed that in samples with N = 4 x 10"j cm-3 spin resonance was also plasma-shifted to lower fields. As the authors in [25] showed, the SR position in the transverse Voigt geometry should be shifted from o = W , to the condition W = (of + fo;)"',…”

Exchange Integrals in Hg0.95Mn0.05Se Obtained by the Wave Shape Analysis of Shubnikov-de Haas Oscillations

“…The strength of this interaction is characterized by two constants (exchange integrals), α and β for s-d and p-d type coupling, respectively [1]. The experimental determination of these parameters is possible either by intraband [2] and interband [3] magnetooptical transitions, and also by fitting Shubnikov-de Haas (SdH) oscillations [4][5][6][7][8]. In narrow gap semiconduction the separating out of contributions involving α and ßis particularly difficult, because of mixed (s-and p-like) character of the band carrier wave function.…”