Metal–insulator transition in manganese‐doped InSb crystals

Abstract

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.

Mn doped InSb studied at the atomic scale by cross-sectional scanning tunneling microscopy

“…This agrees with the study of Obukhov et al, 20 where it is shown that Mn in InSb acts as a shallow acceptor with a binding energy of about 9 meV. 21,22 If we image the cleaved surface at negative voltages (filled state imaging) we observe circular symmetric contrast. For Mn in GaAs we know that the acceptor at these tunnel conditions is ionized due to the band bending.…”

Transport and magnetotransport effects in indium antimonide doped with manganese within quasimetal‐insulator transition

“…Our previous studies on p-InSb(Mn) crystals revealed [4][5][6] Colossal Negative Magnetoresistance and Hall constant sign inversion within N cr in a magnetic field -similar effects as observed in magnetic compounds [7][8][9][10]. The aim of this work is to study the influence of the manganese impurity concentration on transport and magnetotransport effects of p-InSb(Mn) crystals within N cr , to compare and discuss similar effects in SCES.…”

Electronic structure of substitutional Mn in epitaxial In0.965Mn0.035Sb film

“…In these alloys, Mn forms acceptor levels that are shallow or resonant with the valence band potentially leading to enhanced exchange interactions. [2][3][4] For example, recent reports on InMnAs alloy grown by metalorganic vapor phase epitaxy ͑MOVPE͒ have shown the presence of spin polarized itinerant carriers at room temperature. 5,6 While the detailed origin of the exchange interaction in this alloy system is controversial, the source of the localized spins has been attributed to atomic scale complexes consisting of electronically active dimers ͑Mn 2 ͒ and trimers ͑Mn 3 ͒ that stabilize the ferromagnetism.…”

“…8 InMnSb is another narrow bandgap DMS alloy system where the substitutional Mn forms a shallow acceptor level. 2,3 However, the solubility of Mn in InSb is limited. Thus prior work on this alloy has been centered on thin films grown by low temperature molecular beam epitaxy ͑MBE͒, 9,10 and liquid phase epitaxy.…”