Peculiarities of the exchange interaction in narrow-gap Hg_1-x-yCd_xMn_ySe

Abstract

The peculiarities of the exchange interaction between the carrier spin and localized spin moments of magnetic ions near the semimetal-semiconductor transition have been studied in a semimagnetic quaternary solid solution system, Hg 1−x−y Cd x Mn y Se (x = 0.10, y = 0.02, E g = 45 meV), by means of Shubnikov-de Haas oscillations. The measurements show that the exchange 'constant' α is actually a somewhat complicated function α of energy gap E g and electron concentration, which changes from negative values ( αN 0 = −0.15 eV) at lower electron concentration to positive values ( αN 0 = 0.28 eV) at higher electron concentration, values which are more typically associated with wide-gap semimagnetic semiconductors.

Effective renormalization of the exchange interaction at very narrow energy gap in II–VI diluted magnetic compounds

“…1 depicts the calculated α * (E g ) dependences for a particular set of energy band parameters taken for narrow-gap Hg 1−x−y Cd x Mn y Se crystals. The dependences reproduce qualitatively the functional dependence of α * found for Hg 1−x−y Cd x Mn y Se crystals from the oscillating magnetoresistance measurements [4]. Fig.…”

“…A strong reduction of the s-d exchange interaction with increasing degree of the confinement in diluted magnetic (Cd,Mn)Te/(Cd,Mn,Mg)Te quantum well structures has been observed and interpreted in terms of the kinetic exchange for the conduction electrons with finite k vectors [3]. Moreover the parameter α derived from the Shubnikov-de Haas measurements in narrow-gap Hg 1−x−y Cd x Mn y Se crystals occurs as a function of E g and electron concentration [4].…”

Exchange Interaction Between Carriers and Magnetic Ions in Quantum Size Heterostructures

“…Renormalization of the exchange interaction constants for the electrons with large confinement energy was observed in the papers [32,[52][53][54][55][56]. In [32], the structure based on the widegap semiconductor (CdMnTe) was investigated, while in [52,53] the narrow gap semiconductor structure (HgCdMnSe) was studied.…”

“…In [32], the structure based on the widegap semiconductor (CdMnTe) was investigated, while in [52,53] the narrow gap semiconductor structure (HgCdMnSe) was studied. In the papers [54,55], this effect was investigated in GaMnAs structures.…”

Diluted magnetic A1-xMnxB semiconductors

“…Thus, one has in the case of exchange interaction between the spin of conduction band electron and the localized magnetic moment of the Mn ion Usually, the α, β parameters being derived from magneto-optical or magneto-transport experiments reveal a strong scatter both by values and signs even for the most investigated wide-gap semiconductors. Moreover, in the case of narrow-gap semiconductors demonstrating the metallic properties, it is problematically to determine these microscopic parameters from experiments [7,8]. In the limiting case of metal, there exists only one band and only one parameter remains to describe the exchange interaction between collectivized carriers and localized spins.…”