PACS 71.30.+h, 72.20.My, 72.80.Ey, 75.47.Pg Transport properties of manganese-doped InSb crystals with hole concentration close to the critical concentration N cr of the metal -insulator transition (MIT) in p-InSb(Mn) was found to be different from MIT in semiconductors doped with non-magnetic impurities such as p-Ge(Ga), p-Si(P) and p-InSb(Ge). On the insulator side of the transition (N Mn ≤ N cr = 2 × 10 17 cm -3 ) in the range of hole concentration p = 1 -2 × 10 17 cm -3 an activation type of conductivity with energy gap ∆ = 7 × 10 -6 -10 -3 eV was observed. Thus, the usually observed variable range hopping conductivity in crystal semiconductors doped with non-magnetic impurities at low and super-low temperatures was not revealed in p-InSb(Mn) at p ≤ N cr . An external magnetic field decreased ∆ and caused a giant decrease of specific resistivity (ρ 0 /ρ B ~ 10 4 at T ≤ 0.3 K and B ≥ 3 T). On cooling to temperatures below T = 1.5 K the Hall constant changed sign at B < 3 T. The change of Hall constant sign with decrease of temperature means that conductivity of p-InSb(Mn) and crystals compensated with Te -p-InSb(Mn, Te) -at low temperatures was caused by electrons. The proposed model associated an activation energy ∆ at p ~ N cr with the energy gap between sub-bands formed in the impurity band.

InSb crystals doped with manganese within the critical concentration of metal‐insulator transition (Ncr = 2×1017 cm‐3) demonstrate colossal negative magnetoresitance and Hall constant sign inversion at low temperatures in magnetic field – unusual for nonmagnetic materials. Studies of the magnetotransport and conductivity dependency on temperature and manganese concentration revealed that both holes and electrons influence the effects. An excitonic insulator phase conception is proposed as a new approach for the explanation of conductivity and magnetotransport anomalies in p‐InSb(Mn). (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

We report magnetotransport investigation of nonmagnetic InSb single crystal doped with manganese at Mn concentration NMn ~ 1,5 × 1017 cm−3 in the temperature range T = 300 K–40 mK, magnetic field B = 0–25T and hydrostatic pressure P = 0–17 kbar. Resistivity saturation was observed in the absence of magnetic field at temperatures below 200 mK while applied increasing external magnetic field induced colossal drop of resistivity (by factor 104) at B ~ 4T with further gigantic resistivity increase (by factor 104) at 15T. Under pressure, P = 17 kbar, resistivity saturation temperature increased up to 1,2 K. Existing models are discussed in attempt to explain resistivity saturation, dramatic influence of magnetic field and pressure on resistivity with the focus on possible manifestation of three dimensional Wigner crystal formed in InSb by light electrons and heavy holes.