Magnetoplasma Waves in Bismuth and Semimetallic BiSb Alloys at Microwave Frequencies 9 to 100 GHz

Self Cite

Recent investigations on the propagation and damping of magnetoplasma waves in semi-metallic BiSb alloys allow for the conclusion that the effective masses of the holes and the tilt angle of the electron ellipsoids of the Fermi-surface do not vary in the semimetallic region of the alloy system. The variations of the effective masses for the electrons with alloy composition can he deduced from magnetoplasma wave data and are in good agreement with cyclotron resonance-and quantumoscillation experiments. Observation of the wave damping for different measuring configurations indicates, that the relaxation time for the holes decreases more strongly with increasing Sb-concentration than the relaxation time for the electrons does.Neuere Untersuchungen zur Ausbreitung und Dampfung von Magnetoplasmawellen in halbmetallischen BiSb-Legierungen erlauben den SchluB, daB sich die effektiven Massen der Locher und Kippwinkel der Elektronenellipsoide der Fermiflache im halbmetallischen Bereich des Legierungssystems nicht andern. Die Anderungen der effektiven Massen fur Elektronen mit der Legierungszusammensetzung konnen aus den Werten der Magnetoplasmawellen gewonnen werden und sind in guter ubereinstimmung mit Zyklotronresonanz-und Quantenoszillationsexperimenten. Das Verhalten der Wellendampfung fur verschiedene MeBanordnungen zeigt, daB die Relaxationszeit fur die Locher mit zunehmender Sb-Konzentration starker abnimmt als die Relaxationszeit fur die Elektronen.

Section: Effective Musses For Electrons and Holesmentioning

confidence: 96%

Section: Effective Musses For Electrons and Holesmentioning

confidence: 97%

Section: Effective Musses For Electrons and Holesmentioning

confidence: 98%

Section: Effective Musses For Electrons and Holesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Relaxation Time and Effective Masses for Charge Carriers in Semimetallic BiSb Alloys versus Alloy Composition

Braune

Straubel

Kubicki

et al. 1981

Self Cite

Determination of the Cyclotron Masses of the Conduction Band of Bi_1−xSb_x near the Semimetal‐Semiconductor Transition

Fellmuth¹,

Krüger²,

Rudolph³

et al. 1980

In a number of n-doped Bil -%Sb, samples approaching the semimetal-semiconductor transition (0.070 5 x 5 0.083), the propagation of magnetoplasma waves is investigated in the B 1 C, I I k orientation a t 4.2 K. The plane-parallel samples are prepared from a single crystal exhibiting a slight gradient in the antimony concentration. By means of an ellipsoidal model of the conductivity tensor, the low cyclotron mass mg and the anisotropy mz/m$ are determined from the experimental dependence of the wave vector on the frequency and the magnetic field. In the samples with x < 0.073, the dispersion and the attenuation of the waves show peculiarities which can be explained by the presence of holes a t the point T. The results obtained indicate a continuous dependence of the band characteristics on the antimony concentration in the neighbourhood of the point xo, where the overlapping of the bands a t L and T is removed.An einer Reihe von n-dotierten Bil -,Sb,-Proben nahe dem Halbmetall-Halbleiter-ubergang (0,070 (= x 5 0,083) wird die Ausbreitung von Magnetoplasmawellen in der Orientierung B 1 C2 11 k bei 4,2 K untersucht. Die planparallelen Proben werden aus einem Einkristall herausprapariert, der einen schwachen Gradienten in der Antimonkonzentration besitzt. Mit Hilfe eines ellipsoidalen Modells fur den Leitfahigkeitstensor werden aus der experimentellen Abhangigkeit des Wellenvektors von der Frequenz und vom Magnetfeld die kleine Zyklotronmasse mh und die Anisotropie m$/mg bestimmt. Bei den Proben mit x < 0,073 treten Besonderheiten in der Dispersion und der Diimpfung der Wellen auf, die mit dem Vorhandensein von Lochern am T-Punkt erklart werden konnen. Die erhaltenen Ergebnisse geben Hinweise auf eine stetige AbhLngigkeit der Bandcharakteristika von der Antimonkonzentration nahe dem Punkt z,,, wo die nberlappung der Bander in L und T aufgehoben wird.

Electronic pecularities in Bi_1−xSb_x alloys close to the semiconductor‐semimetal transition at x ≈︁ 0.22

Braune

Kubicki

Straubel

et al. 1981

F r o m investigations on the propagation of magnetoplasma waves it is known that in the semiconducting range of the alloy system obviously a qualitatively new configuration of the band structure occurs at x = 0.14 t o 0.15, leading to peculiarities in the dependence of the band structure parameters on alloy composition that are not only due t o the fundamental energy gap. By means of magnetoplasma wave investigations in the binary plane a strong increase in the anisotropy of c c c the cyclotron m a s s e s m / m (m. cyclotron masses of the electrons i n the ma-3 2 1 j o r axes system of the F e r m i bodies) has been found in this range /l/. Up t o now the investigation of these characteristics in alloys above x 5*r 0.16 has failed, as the cyclotron m a s s e s of the ''heavy" electrons o r the magnetoplasma resonances in this alloy range are difficult to detect Now, f o r the first time, magnetoplasma resonances have been recorded immediately before the semiconductor-semimetal transition at an alloy composition of x = 0.214. The experimental set-up was based on a carcinotron (see /2/). We succeeded in investigating the propagation of magnetoplasma waves in the whole binary plane in the Voigt configuration (c II c21 3, wave v e c t o r , C2 binary axis) at microwave frequencies from 76 t o 11 0 GHz as well as in the Faraday configuration (d II 82 I 1 3 ) at 30.3 GHz (utilizing the transmission through a resonator /2/) in several samples of this alloy composition having different thicknesses (d = 0.22, 0.45, 0.55 mm). The samples were prepared by cutting parallel slices from one crystal. The antimony concentration was determined by means of microprobe investigations resulting in x = 0.21 4 with an e r r o r of for all these samples.-In Fig. 1 recordings are shown in both configurations 8 I 1 3' and 8 II a', i. e. in these configurations in which the magnetic field is directed parallel to the 1) Hessische Str. 2, DDR-1040 Berlin, DDR.