Magnetoresistance of GaP0.4As0.6 Whiskers in Vicinity of MIT

Authors A.A. Druzhinin , N.S. Liakh-Kaguy , I.P. Ostrovskii , Yu.M. Khoverko

Lviv Polytechnic National University, 12, S. Bandera St., 79013 Lviv, Ukraine

Issue Volume 11, Year 2019, Number 4
Dates Received 03 May 2019; revised manuscript received 05 August 2019; published online 22 August 2019
Citation A.A. Druzhinin, N.S. Liakh-Kaguy, I.P. Ostrovskii, Yu.M. Khoverko, J. Nano- Electron. Phys. 11 No 4, 04007 (2019)
PACS Number(s) 73.43.Qt, 71.30. + h
Keywords Whiskers (3) , Negative magnetoresistance, Hopping conduction, Spin-dependent scattering.

The magnetoresistance of GaP04As06 whiskers doped with silicon with a concentration of acceptor impurity in the range of Na  1  1017  5  1018 сm – 3 was investigated. The study of the magnetoresistance of GaAs whiskers at cryogenic temperatures gives information on the nature of low-temperature conductivity in such crystals, and can also be used to create magnetic field sensors with a magnetoresistive principle of action. It is interesting to investigate the magnetotransport properties of GaPxAs1 – x solid solution. The purpose of this work was to study the magnetic support of GaP0.4As0.6 whiskers doped with silicon with a concentration of acceptor impurity in the range of Na  1  1017  5  1018 сm – 3 at low temperatures. The composition of the solid solution was chosen from the point of view of the change in the band structure of the varizonic semiconductor. The concentration of charge carriers in crystals was in the vicinity of the metal- insulator transition (MIT). In this work, the transverse and longitudinal magnetoresistances of the whiskers were studied in the range of 4.2-77 K in magnetic fields up to 12 T. For most samples, the exponential temperature dependence of the resistance is obtained, which corresponds to the dielectric side of the MIT. It is established that in the transverse and longitudinal magnetic fields the field dependence of the magnetoresistance of the crystals is quadratic and is determined mainly by the conductivity of localized A+ states of the upper Hubbard zone. However, at low temperatures of 4.2-50 K, a negative magnetoresistance (up to 7 %) in weak magnetic fields (up to 4.5 T) was detected in GaP0.4As0.6 whiskers. A critical magnetic field was determined, in which a transition from negative to positive magnetoresistance occurs. It is shown that the magnitude of the critical magnetic field depends on the temperature and nature of the application of the magnetic field. The possible reasons for the appearance of a negative magnetic resistivity were analyzed: dimensional effect, distribution of impurities in the whiskers. The obtained results indicate that the mesoscopic dimensional effect does not appear in the studied samples due to sufficiently large crystal sizes. The results of mass spectroscopic studies have established a homogeneous distribution of impurities indicating the absence of clusters in the samples. The obtained negative magnetoresistance was probably connected with antiferromagnetic exchange interaction of the magnetic moments of charge carriers in the process of their hopping conductance on the delocalized states of the upper Hubbard zone.

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