Investigation of the gapless state in bismuth-antimony alloysстатья
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Дата последнего поиска статьи во внешних источниках: 22 ноября 2015 г.
Аннотация:The results are presented from an experimental study of the gapless state produced in semiconducting alloysBi 1−x Sb x by pressure-induced band inversion. The magnetoresistance properties of the alloys have been investigated both in weak magnetic fields (μH « 1) and in strong fields (H≤75 kOe) at liquidhelium temperatures in the Sb concentration interval 0.06≤x≤0.15 and pressure interval 1 bar ≤p<20 kbar. At pressuresp close to the pressurep k at which the gapless state is realized a “semiconductor-semimetal-semiconductor” transition is detected inBi 1−x Sb x alloys withx=0.070 and 0.071. The rates of change of the gap ε gL before and after inversion are determined: −(2.5±0.5)×10−6 eV/bar and (1.5±0.5)×10−6 eV/bar, respectively. A reduction in the carrier effective mass as ε gL → 0 is observed down to values of ∼ 10−4 m 0. It is shown that as ε gL → 0 the carrier mobilities in the alloys increase abruptly, the effect being a maximum in the purest alloys, where forT=4.2 K the mobility along the binary axis attains the record-high value of ∼ 3×108 cm2/V · sec.