L. D. Paranchich

Anomalous low-temperature contribution to the heat capacity from hybridized electronic states on transition element impurities

An anomalous nonmonotonic contribution to the temperature dependence of the electron heat capacity of mercury selenide is detected. This is explained in terms of hybridized electronic states on donor impurities. The observed effect is described by a theory of electron heat capacity based on a quantum Fermi-liquid approach including localization and electron-electron interactions. A quantitative interpretation of the experimental dependences yields values for the parameters of the hybridized states that are consistent with those known from other experiments. A new parameter characterizing the electron-electron interaction in the hybridized states is also found.

Experimental discovery and theoretical description of the anomalous hall effect in a spontaneously polarized electron system of hybridized impurity states

An anomalous magnetic-field-independent contribution to the Hall resistance of mercury selenide crystals with a small iron impurity has been discovered in room-temperature experiments. This contribution has been shown to be due to spontaneous polarization of the electron system of hybridized impurity states. The theoretical explanation of the effect based on the thermodynamic description of dissipationless electron current in the spontaneously polarized electron system has been proposed.

Experimental observation of spontaneous spin polarization of electrons in hybridized states of transition element impurities in semiconductors

Experimental evidence of the possible existence of spontaneous spin polarization of the electron system in hybridized states formed by transition element impurity atoms in the conduction band of semiconducting crystals is examined. The details of a quantitative interpretation of experiments on the temperature dependence of the specific heat and elastic moduli of mercury selenide crystals with iron impurities confirm the feasibility of establishing the presence of electron spin polarization in this type of experiment, as well as the possible existence of polarization in the crystals studied here. Theoretical arguments support the observation of a thermodynamic anomalous Hall effect owing to spontaneously polarized donor electrons from low-concentration impurities.

Anomalies in the temperature dependence of the contribution to the speed of sound from hybridized electronic states of transition element impurities

The temperature dependence of the speed of sound in crystalline mercury selenide with low concentrations of iron impurities is studied. Experiments are conducted in the ranges of concentration and temperature where hybridized electronic states in iron impurities have been observed previously. It is found that at temperatures below 10 K the speed of slow transverse ultrasonic waves has an anomalous nonmonotonic segment of its temperature variation that is related to the influence of the impurities and reflects the existence of hybridized states. The observed anomalies in the sound speed are described in terms of a theory for the electron contribution to the elastic moduli that includes hybridization of impurity states and electron-electron interactions. Fits of the theoretical dependences to the experimental data yield quantitative information on the parameters of the hybridized states and of the Fermi-liquid interaction.

Effect of Fe, Co, and Cr impurities on the thermoelectric properties of Cd x Hg1−x Se

We have studied the effect of doping with 3d transition metals (iron, cobalt, and chromium) on the thermoelectric properties of single crystals of CdxHg1−xSe solid solutions at temperatures from 77 to 400 K and the effect of thermal annealing in Hg or Se vapor on their electrical properties. The results indicate that chromium and cobalt produce no energy levels in the band structure of CdxHg1−xSe solid solutions. Therefore, these dopants do not create resonant donor levels superimposed on continuum states of mercuric selenide. Fe doping produces an energy level whose position can be controlled by varying the composition of the solid solutions.

Optical and transport properties of Fe-doped Cd x Hg1−x Se (x = 0.35)

The optical and transport properties of Fe2+-doped CdxHg1−xSe crystals with a midgap Fe2+ level have been studied. The results demonstrate that Fe2+ ions influence both the optical and transport properties of CdxHg1−xSe〈Fe2+〉. The observed optical absorption bands are due to a donor Fe2+ level in the band gap, with a depth EFe = 0.21 eV, and to band-band transitions. Thermal anneals in Hg and Se vapors have different effects on the carrier concentration and mobility in the crystals. The effect of annealing on the transport properties of the Fe2+-doped crystals differs from that for undoped crystals and is governed by the state of point defects.

Spin ordering contribution of iron, cobalt, and nickel impurity electron states, to the low-temperature magnetic susceptibility of mercury selenide crystals

A study of the magnetic susceptibility of electron systems of hybridized states of iron, cobalt, and nickel impurities in mercury selenide crystals at low temperatures, in connection with newly discovered evidence of spontaneous spin polarization in the anomalous Hall effect, at room temperature. It is shown that in the measured paramagnetic susceptibility of electrons in hybridized states, there exists a temperature-independent portion, and that there is enough justification to identify it using spontaneous polarization. The other portion demonstrates the Curie law with decreasing temperature, and corresponds to contributions from nonpolarized electrons. Based on findings relating to the magnetization of the examined impurity systems, we identify a part of the spontaneously polarized electron density in the localized component of hybridized states. We give quantitative estimates of the aforementioned portions of each impurity.

Microwave Magnetoabsorption Oscillations in Fe-Doped HgSe Crystals

Magnetoresistance oscillations are considered in the case of microwave-radiation absorption in HgSe samples with a different Fe-impurity concentration. From the simultaneous analysis of the field and temperature dependences of the Shubnikov–de Haas oscillations, the effective mass, the Dingle temperature, and the quantum-limit field corresponding to the Fermi level are obtained. A method for analyzing the spectra with several oscillation frequencies, i.e., the beating effect, is proposed. The results are compared with data obtained by Hall measurements.

Electrical properties and microstructure of CdxHg1 − x − yCrySe crystals

Crystals of the CdxHg1 − x − yCrySe (x = 0.4, y = 0.1) quaternary solid solution have been grown by the Bridgman method, and their microstructure and electrical properties have been studied. The crystals are shown to contain various types of inclusions in the form of filaments and triangles.

Magnetic ordering in CrxHg1 − xSe crystals grown by solid-state recrystallization

CrxHg1 − x crystals grown by solid-state recrystallization have been characterized by electron paramagnetic resonance spectroscopy, transport measurements, and X-ray microanalysis. The results demonstrate that the crystals contain rectangular HgCr2Se4 inclusions elongated along one of their axes and irregularly shaped CrxHg1 − x and CrHg inclusions. In the range 77–400 K, the electrical properties of samples cut from different parts of the crystals are typical of semiconductors with a strongly degenerate electron gas.