We review the physical properties of diluted magnetic semiconductors (DMS) of the type AII1−xMnxBVI (e.g., Cd1−xMnxSe, Hg1−xMnxTe). Crystallographic properties are discussed first, with emphasis on the common structural features which these materials have as a result of tetrahedral bonding. We then describe the band structure of the AII1−xMnxBVI alloys in the absence of an external magnetic field, stressing the close relationship of the sp electron bands in these materials to the band structure of the nonmagnetic AIIBVI ‘‘parent’’ semiconductors. In addition, the characteristics of the narrow (nearly localized) band arising from the half‐filled Mn 3d5 shells are described, along with their profound effect on the optical properties of DMS. We then describe our present understanding of the magnetic properties of the AII1−xMnxBVI alloys. In particular, we discuss the mechanism of the Mn++‐Mn++ exchange, which underlies the magnetism of these materials; we present an analytic formulation for the magnetic susc...

Diluted magnetic semiconductors

Optical Properties of (Zn, Mn) and (Cd, Mn) Chalcogenide Mixed Crystals and Superlattices

Publisher Summary This chapter discusses low-dimensional structures of II–VI diluted magnetic semiconductors (DMS) with manganese and describes the carrier concentration induced ferromagnetism in Mn-based IV–VI DMS with a particular emphasis on Mn content and conducting hole concentration dependent paramagnetic–ferromagnetic–spin glass transitions in bulk crystals and thin layers of SnMnTe and related materials. The chapter also discusses the transport, magnetic, and optical properties of bulk crystals and thick epitaxial layers; low-dimensional quantum structures of IV–VI DMS with Eu; the magnetic and electrical properties of IV–VI semiconductors with Gd; and the magnetic and optical properties of all semiconductor ferromagnetic multilayers built of ferromagnetic EuS and nonmagnetic IV–VI (PbSe and PbS) semiconductors. The chapter describes DMS containing transition metals other than manganese. These materials never attracted as much attention as the ones containing Mn, mainly because of severe difficulties in their preparation, particularly when large percentages of the magnetic components were involved.

II–VI and IV–VI Diluted Magnetic Semiconductors – New Bulk Materials and Low-Dimensional Quantum Structures

Publisher Summary This chapter discusses the diluted magnetic semiconductors (DMS). New aspects of DMS physics are reviewed and an update of various numerical data that are relevant to DMS materials is provided. The specific nature of DMS makes it impossible to leave out those properties that are typical for semiconductors. The information concerning crystal structures and lattice constants of diluted magnetic semiconductors is presented in the chapter. The properties of these semiconducting mixed crystals in the absence of an external magnetic field are described. The quantities typically considered when discussing semiconducting materials, such as, energy gaps, separating valence, and conduction bands are also focused. Magnetic properties are presented, which is followed by where properties that single out DMS as a separate group of materials are discussed, namely those that are connected with a mutual dependence of the magnetic and semiconducting properties. This interdependence stems from strong exchange coupling between the conduction band electrons and/or valence band holes with the localized electrons from 3d shells of ‘magnetic’ ions, which form localized magnetic moments. The materials that are most commonly considered as the members of the DMS family are substitutional solid solutions of II—VI semiconductors and transition-metal monochalcogenides such as CdTe and MnTe.

Chapter 4 Diluted magnetic semiconductors

A review is given of optical properties of the new II-VI strained layer superlattice based on the CdTe/(Cd,Mn)Te heterostructure. Emphasis is given to excitonic phenomena and their contribution to the present but early understanding of electronic characteristics of multiple quantum wells grown by molecular beam epitaxy. The CdTe/ (Cd, Mn)Te system has a number of unique features including its magneto-optical properties, rather weak confinement of hole states, possibility of growth in two different crystalline orientations, and strong influence of interface states.

Optical properties of CdTe/(Cd, Mn)Te multiple quantum wells

We present a variational calculation of the energy levels of an exciton confined to a CdTe quantum well by semimagnetic (Cd,Mn)Te potential barriers. The degeneracy of the top of the valence band is lifted by strain and quantum confinement effects, introducing a preferential axis of quantization for the heavy \ensuremath{\Vert}${m}_{j}$\ensuremath{\Vert}=(3/2) doublet. This results in strongly anisotropic magnetic field shifts of the levels. The shifts are greatly enhanced due to the penetration of the wave functions into the barriers, where they are subject to the exchange potential of the polarized Mn spins. Our results are in good qualitative agreement with recent photoluminescence data on CdTe-(Cd,Mn)Te superlattices.

da Silva Ce

Papers

Magnetic polaron effects for excitons in narrow CdTe-(Cd,Mn)Te quantum wells.

Bound magnetic polarons in semimagnetic quantum wells.