A. V. Filatov

Dislocations in manganese-doped InSb

Electron probe X-ray microanalysis data for quenched InSb〈Mn〉 samples demonstrate that most of the manganese goes to doping of dislocations in the semiconductor lattice. The manganese-doped dislocations in InSb determine the magnetic and electrical properties of the material at room temperature and above. According to magnetic measurements, this is accompanied by the formation of several magnetic phases. Codoping of InSb with manganese and zinc with the aim of neutralizing one of the magnetic phases allowed us to obtain a ferromagnetic semiconductor with a Curie temperature of 320 K.

Manganese solubility in quenched InSb

We have studied the magnetic properties of supersaturated In1 − xMnxSb substitutional solid solutions prepared by quenching from the liquid state. All of the materials in the range 0.07–2 at % Mn were found to be ferromagnets. Judging from their Curie temperatures, they contained microinclusions of variable composition, similar to solid solutions based on the ferrimagnetic compound Mn2Sb at Mn contents below 0.5 at % and to solid solutions based on the ferromagnetic compound MnSb at higher Mn contents.

InSb codoped with Mn and Zn: A new ferromagnetic semiconductor

We have studied the magnetic properties of In1 − xMnxSb substitutional solid solutions. The results indicate that, at Mn contents below 0.5 at %, the materials contain microinclusions close in composition to the ferrimagnetic compound Mn2Sb, which has a layered structure with magnetically active manganese in two structurally inequivalent sites, Mn1 and Mn2. Zinc doping of Mn2Sb breaks up one of its magnetic sub-lattices and converts the ferrimagnet to a ferromagnet. This property is basic to the proposed ferromagnetic semiconductor based on InSb codoped with Mn and Zn, which has a Curie temperature near 320 K.

Cluster magnetism in doped InSb

Magnetic properties of indium antimonide doped by Mn and by, simultaneously, Mn and Zn, and Mn and Cd have been analyzed. It has been established that the basic contribution to the formation of the magnetic properties of these materials comes from clusters, whose composition and Curie temperature change depending on the content of manganese, zinc, and cadmium.

Microstructure of quenched doped InSb

Magnetic characterization results indicate that, after liquid quenching, InSb samples doped with manganese, manganese + zinc, and manganese + cadmium are magnetic semiconductors. According to microstructural analysis data, polished sections of these materials demonstrate surface order: the grains have the form of wedges directed from the periphery of the section to its center, occupy essentially the entire surface of the section, and have low-angle boundaries with dislocation outcrops on the sample surface. According to X-ray diffraction data, quenched doped InSb samples are free of impurity phases and have preferential crystallographic orientations. Analysis of the present experimental data leads us to conclude that the surfaces of metallographic specimens of doped InSb are sections through textures whose orientation—under given quenching conditions—depends on the dopant composition.

Magnetically soft semiconductor InSb〈Mn,Zn〉 with the curie temperature of 320 K

The magnetic properties of a ferromagnetic semiconductor based on indium antimonide doped with manganese and zinc having the Curie temperature Tc = 320 K are studied. Field dependences of magnetization of InSb〈Mn,Zn〉 recorded at 4 and 260 K indicate that this material is magnetically soft with the coercive force no higher than 18 Oe at T = 300 K.

Ferromagnetism of GaSb (2% Mn) alloy

A polycrystalline sample of composition GaSb + 2% Mn was prepared by melt quenching. Manganese substitutes for gallium positions to form limited solid solution Ga1 − xMnxSb, as shown by X-ray powder diffraction and SEM, but most manganese is consumed in the formation of magnetically ordered Mn1.1Sb inclusions having the Curie point TC ≈ 560 K, as shown by magnetic studies.

Topographic analysis of the surface of the GaSb〈Mn〉 magnetic semiconductor

We have studied the formation of magnetic properties on the impurity–dislocation magnetism principle in a sample of a manganese-doped gallium antimonide compound semiconductor prepared by melt quenching. It has been shown using X-ray diffraction, optical microscopy, and scanning electron microscopy that the generation of dislocations and their motion during quenching play a key role in determining the microstructure of the GaSb〈Mn〉 magnetic semiconductor.

Synthesis and properties of magnetic semiconductor InSb〈Mn,Cd〉

Polycrystalline indium antimonide samples codoped with manganese (0.8–1 at %) and cadmium (3.9 at %) are prepared by quenching from melt. Despite the high contents of these dopants, only InSb maxima are observed in X-ray diffraction patterns of these samples. As probed by magnetic studies, the samples are ferrimagnets having Curie points of about 577 K and room-temperature specific magnetizations of σ ≈ 0.5 G cm3/g (H = 6 kOe). We suggest that the magnetic properties of the samples are dictated by InSb〈Mn,Cd〉 microinclusions, which are located in grain boundaries and dislocations.

Synthesis and magnetic properties of solid solutions In1–xGaxSb〈Mn〉

Manganese-doped solid solutions In1–xGaxSb (x = 0.05, 0.1, 0.5, 0.9, 0.95) were synthesized. It was found that, in samples of the compositions In0.95Ga0.05Sb〈Mn〉 and In0.05Ga0.95Sb〈Mn〉, a homogeneous substitutional solid solution forms, into which manganese-containing clusters are incorporated. The clusters are mainly located at crystal lattice defects—grain boundaries and dislocations. The ferromagnetic properties of the obtained samples at room temperature and higher are caused by clusters Mn1+xSb, the effective size of which is about 180–300 nm.