Low-temperature magnetoresistance of GaSb whiskers

Abstract

Transverse and longitudinal magnetoresistancies in n-type GaSb whiskers with different doping concentration (Te) in the vicinity to the metal-insulator transition (MIT) from metal side of the transition were studied in the temperature range 1.5-60 K and magnetic field 0-14 T. Shubnikov-de Haas oscillations in GaSb whiskers at low temperatures were revealed in magnetic field range 2-12 T. The oscillation period 0.025T -1 was found at various doping concentration in GaSb whiskers. The effective mass of electrons m с = 0.041m 0 and Dingle temperature of about 7.5 K were found in GaSb whiskers with impurity concentration in the vicinity to MIT. The presence of negative magnetoresistance in GaSb whiskers with the impurity concentration in the nearest approximation to MIT with resistivity ρ 300K = 0.0053 Ω·сm was observed and associated with weak localization. Besides for the whiskers a resistance minimum was observed at temperature about 16 K that is connected with Kondo effect. Magnetoresistance studies of n-type conductivity for GaSb whiskers revealed the crossover from weak localization to antilocalization in the temperature range of 1.4-4.2 K and magnetic fields below 1 T.

Doping Dependent Magnetic Behavior in MBE Grown GaAs1-xSbx Nanowires

“…However, we note that the p-type behavior of the underlying GaAs stem results from Ga vacancies as pointed out earlier. Another potential origin of ferromagnetism in our doped nanowires may lie in strong magnetic ordering of the 5p spins on the Te dopant atoms when the dopant concentration is near the MIT as suggested by Druzhinin, et al 17,18 and is the case in our samples. Coey 52 has recently discussed the complexity of temperature independent d 0 FM in oxides with non-magnetic cations and concluded that currently available data cannot be explained via our conventional understanding.…”

“…Furthermore, the fact that ferromagnetism is observed in our doped semiconductor nanowires but not intrinsic ones suggests that it is dopant induced. We note that the doping concentration in our doped nanowires, mid-10 18 cm −3 , is in the vicinity of the metal-insulator transition (MIT) as reported by Druzhinin, et al 17,18 , which was relevant to their magnetoresistance (MR) behavior. They demonstrated that negative MR due to strong magnetic ordering occurred only when the carrier concentration of the non-magnetic Te impurities was within the MIT regime.…”

“…Both Sn-doped InSb and Te-doped GaSb whiskers with diameters in the 20-40 μm range exhibit negative magnetoresistance when the dopant concentration is near the metal-insulator transition 16,17 . Furthermore, Te-doped GaSb whiskers are reported to reveal a superconducting phase below 4 K 18 .…”

Evaluation of the thermal regime of the cathode operation of a high-voltage glow discharge electron gun, which forms a ribbon electron beam

“…Another, more accurate approach to describing the geometry of complex three-dimensional objects is the use of Rvachev functions, or locus [37][38][39]. The essence of this approach is that instead of the logical ratios used in the analytical expression (6), atomic functions or locus are used. Locus is smooth functions with a high value of the derivative.…”

“…Then the sophisticated arithmetic-logical relation (6), taking into account (7), will be rewritten as follows:…”