Exchange Interaction of Manganese 3d⁵ States with Band Electrons in Cd_1−xMnxTe

Abstract

The influence of a system of magnetic-field-aligned paramagnetic ions on the conduction and valence band electron states is studied. A modelapplicable to large-gap semiconductors is presented, in which the direct influence of a magnetic field on the band electron states is neglected. This assumption allows to calculate the E ( k ) dependence in the presence of a magnetic field. The calculations are performed in the Kohn-Luttinger model producing a strongly anisotropic and nonparabolic structure. As an illustration of the obtained results measurements of the exciton reflection structure in a magnetic field are presented on the ternary semiconductor CdMnTe.

Luminescence of Cd0.7Mn0.3Te crystals in magnetic field: Linewidth, Landau quantization, and carrier effective mass

“…Many authors [1,4,6] agree that a simplified form of transition energy description is sufficient, but the accuracy of applied approximation in various magnetic field ranges is rarely discussed. Relying on performed analysis of Cd 0.7 Mn 0.3 Te luminescence results, the accuracy of both possible descriptions of transition energy could be evaluated in weak and stronger magnetic field ranges.…”

“…The influence of local magnetic moments of Mn 2+ ions on the band structure of the host semiconductor is determined by the exchange interaction of Mn 2+ 3d 5 electrons with band (s, p) electrons. In magnetic field the energy splitting of band states is supplemented by an additional term describing the Mn 2+ -ion-induced s, p − d exchange interaction effect: xN 0 α S z or xN 0 β S z (for conduction or valence band respectively) [4]. Here N 0 is the number of elementary cells per unit volume, α is the s − d exchange integral for Γ 6 conduction band electrons, β is the p − d exchange integral for Γ 8 band holes, S z is the thermodynamical average of Mn 2+ ion spin along the steady magnetic field B, and x is the Mn mole fraction.…”

“…In this approximation magnetic-field-induced splittings of conduction and valence band edges are described by ∆E c = −xN 0 α S z m j (m j = ±1/2) and [2,3]. As result, the conduction band at Γ 6 point splits into two subbands separated by 6|A ex | (A ex = (1/6)xN 0 α S z ) and the valence band at Γ 8 point into four subbands situated equidistantly with the splitting of 2|B ex | (B ex = (1/6)xN 0 β S z ) [3,4]. The N 0 α and N 0 β values determined from experiments are 0.22 eV and −0.88 eV, respectively [6].…”

“…Investigation of semimagnetic semiconductors (SMSCs) goes on for more than several decades and is important both from theoretical and application point of view: due to investigations of s, p − d exchange interaction and possibility to change the band gap value by changing the concentration of magnetic component and applying magnetic field. Experimental results of light emission in SMSCs usually are interpreted in terms of s, p − d exchange interaction theory [4] but the accuracy of this theory is rarely discussed. This paper presents such comparison with experimental luminescence data for Cd 0.7 Mn 0.3 Te crystals.…”

Low-Dimensional Structures of Diluted Magnetic (Semimagnetic) Semiconductors - a Subjective Review

“…Som e very earl y work has b een do ne i n W arsaw and i ts descri pti on can be found i n the revi ews quoted ab ove. Ini ti al moti vati on for the earl y i nterest wa s vari ed: i t ori gi na ted pri m ari l y in an i ntenti on to study an i nteracti on of magneti c and \ semi conducti ng " pro p erti es o f materi al s, but i t stem med al so f rom an extra ordi nari l y hi g h el ectro n m obi li ty observed i n Hg Mn T e by Mo rri ssy [6] and then, m ore speciÙcal ly, fro m, has l ater b ecome kno wn as the gi ant spi n spl i tti ng , observed i n CdMnT e [7,8] and ZnMnT e [9]. Apa rt fro m these m oti vati ons, i n the course of i nvesti gatio ns underta ken, there app eared a spectrum of i nteresti ng pheno mena tha t singl ed out di luted magneti c semi conducto rs as a di sti nct and uni que gro up of m ateri al s. The most i nteresti ng feature of the physi cs of DMS ari ses, of course, fro m the intera cti on b etween conducti on a nd/ or val ence el ectro ns wi th the m agneti c com p onent vi a the spin-dep endent s p À d i ntera cti on.…”