E. Arushanov

• Academy of Sciences of Moldova

Resistivity, ρ ( T ), and magnetoresistance (MR) are investigated in the Cu 2 Zn 1-x Cd x SnS 4 single crystals for compositions x ≡ Cd/(Zn + Cd) = 0.15 – 0.24, in the temperature range of T ~ 50 – 300 K in pulsed magnetic fields of B up to 20 T . The Mott variable-range hopping (VRH) conductivity is established within wide temperature intervals ly...

The phase diagram of the Cu2CdSnS4-Cu2ZnSnS4system was constructed using data on differential thermal, X-ray phase and microstructure analysis methods. The diagram can be attributed to the first type according to the Rosebohm classification. The Cu2CdSnS4-Cu2ZnSnS4 solid solution single crystals were grown by chemical vapor transport using iodine a...

A polarization dependent infrared reflectivity study on oriented single crystal in the range of 100 – 500 cm-1 was performed to investigate the optical phonon modes in the stannite Cu2СdSnS4 semiconductor. Based on the symmetry analysis and multi-oscillator model calculation we determine the parameters of B2 and E polar modes. The values of high fr...

The recent investigation of kesterite type quaternary compounds showed that one of the main detrimental problems, which limits the efficiency of the solar cells based on these materials, is related to the high defect concentrations, mainly CuZn disorder. To overcome this problem partial replacement of Cu or Zn cations in the classical Cu2ZnSn(S,Se)...

Transport properties of the kesterite-like single crystals of Cu2ZnSnS4, Cu2ZnSnxGe(1−x)Se4 and Cu2ZnGeS4 are investigated in pulsed magnetic fields up to B = 20 T. The Mott variable-range hopping (VRH) conduction is established by investigations of the resistivity, ρ (T), in all the materials mentioned above within broad temperature intervals of Δ...

Magnetotransport measurements have been performed on (112)-oriented bulk Cd3As2 samples with in situ rotation at low temperature. The frequency analysis of the Shubnikov-de Haas oscillations reveals two weakly separated frequencies arising from two Fermi ellipsoids. The angle dependence of these frequencies is fitted by an analytical expression tha...

The linear optical properties of Cu2ZnSnS4 bulk poly-crystals have been investigated using spectroscopic ellipsometry in the range of 1.2–4.6 eV at room temperature. The characteristic features identified in the optical spectra are explained by using the Adachi analytical model for the interband transitions at the corresponding critical points in t...

Cadmium arsenide (Cd3As2) has recently became conspicuous in solid-state physics due to several reports proposing that it hosts a pair of symmetry-protected 3D Dirac cones. Despite vast investigations, a solid experimental insight into the band structure of this material is still missing. Here we fill one of the existing gaps in our understanding o...

Cadmium arsenide (Cd3As2) has recently became conspicuous in solid-state physics due to several reports proposing that it hosts a pair of symmetry-protected 3D Dirac cones. Despite vast investigations, a solid experimental insight into the band structure of this material is still missing. Here we fill one of the existing gaps in our understanding o...

We report the detailed optical properties of Cd$_3$As$_2$ crystals in a wide space of parameters: temperature, magnetic field, carrier concentration and crystal orientation. We investigate samples synthesized by three different techniques. The charge density varies locally in all of the investigated samples, which is seen through spatially-resolved...

We report the detailed optical properties of Cd$_3$As$_2$ crystals in a wide parameter space: temperature, magnetic field, carrier concentration and crystal orientation. We investigate high-quality crystals synthesized by three different techniques. In all the studied samples, independently of how they were prepared and how they were treated before...

One of the most detrimental problems in the further development of thin film solar cells based on kesterite type compound semiconductors is the limitation in open circuit voltage (VOC). The latter, according to many theoretical and experimental studies, is mostly related to the high concentration of intrinsic defects, mainly with ZnCu antisites. Re...

Polarized Raman scattering and resonance Raman scattering spectra of Cu2ZnSiSe4 crystals measured at temperature 300 and 10 K were investigated. Nine vibrational modes of A2 symmetry, seven modes of B2 symmetry and nine modes of B1 symmetry were determined in Raman spectra taken at right angle configuration from the (2 1 0) crystal plane. A resonan...

The resistivity, ρ(T), and the magnetoresistance (MR) of Cu2ZnSnS4 (CZTS) single crystals are investigated at temperatures T = 2–300 K in pulsed magnetic fields of B up to 20 T. The Mott variable–range hopping (VRH) conductivity over localized states of the defect acceptor band is observed between T ~ 50–150 K. The Shklovskii–Efros (SE) VRH conduct...

The spray pyrolysis was used for the deposition of Cu2ZnSn(S, Se)4 (CZTSSe) kesterite thin films. The basic spray pyrolysis solution was prepared from two precursor solutions containing thiourea and cooled to a temperature near 1°C, which leads to minimizing the number of insoluble hydrates of copper chloride. The optimal substrate temperature was...

Resistivity, ρ(T, x), of Cu2Zn(Sn x Ge1-x )Se4 (CZTGeSe) single crystals with x = 0-1, investigated at temperatures between T ~ 10-320 K, exhibits an activated character within the whole temperature range, attaining a minimum at x = 0.47. Magnetoresistance (MR) of CZTGeSe with x = 0.26, 0.47 and 0.64 is positive (pMR) in all measured fields of B up...

Activated resistivity, ρ(T), and positive magnetoresistance (MR) are observed in Cu2ZnSnS4 single crystals within the temperature interval between T ∼ 2 and 300 K in pulsed magnetic fields of B up to 20 T. Between T ∼ 50 and 150 K, the charge transfer is described by the Mott variable-range hopping (VRH) transport over localized states of the defec...

Thin Cu2ZnSn(SxSe1-x)4 films with x = 1.0 and 0.85 were prepared by the spray pyrolysis method with subsequent annealing in the presence of elemental sulfur or selenium. The surface sensitive Raman measurements indicated a high crystalline quality of all samples and absence of secondary phases. Small amount of Cu2-xS secondary phase was detected fr...

We report on optical reflectivity experiments performed on Cd3As2 over a broad range of photon energies and magnetic fields. The observed response clearly indicates the presence of 3D massless charge carriers. The specific cyclotron resonance absorption in the quantum limit implies that we are probing massless Kane electrons rather than symmetry-pr...

We report on optical reflectivity experiments performed on Cd3As2 over a broad range of photon energies and magnetic fields. The observed response clearly indicates the presence of 3D massless charge carriers. The specific cyclotron resonance absorption in the quantum limit implies that we are probing massless Kane electrons rather than symmetry-pr...

A comprehensive vibrational analysis of the kesterite Cu2ZnGeS4 semiconductor (space group I4 ) is reported, which includes experimental in-plane rotation polarized Raman scattering measurements from the (101)-single crystal facet as well as first principle lattice dynamic calculations. 17 out of the 27 expected vibrational modes of the kesterite s...

A non-destructive Raman spectroscopy has been widely used as a complimentary method to X-ray diffraction characterization of Cu2ZnSnS4 (CZTS) thin films, yet our knowledge of the Raman active fundamental modes in this material is far from complete. Focusing on polarized Raman spectroscopy provides important information about the relationship betwee...

We present magnetotransport measurements performed on Cd3As2 samples. Our results confirm the existence of 3D Dirac fermions in this material with a π Berry phase. A metal-insulator transition driven by the magnetic field is also observed for B < 1 T. Finally the in situ rotation of the sample reveals that the Fermi surface is a weakly anisotropic...

Spectral and time dependent surface photovoltage (SPV) measurements were performed on Cu 2 ZnSn(S x Se 1-x) 4 (CZTSSe) thin films prepared on ITO/glass substrates by spray pyrolysis at ambient atmosphere from aqueous solutions and subsequent selenization of Cu 2 ZnSnS 4 (CZTS) layers. The morphology, stoichiometry and phases of the crystalline thin...

Cu2ZnSnS4 (CZTS) is one of the most promising compound for utilization in photovoltaic conversion. Besides of the efficiency up to 12.6 % achieved just recently for solar cells based on Cu2ZnSn(S,Se)4 (CZTSSe), CZTS contains low-cost, low-toxic and abundant elements in the crust. The conductivity, magnetoresistance, spectroscopic ellypsometry, Rama...

Cu2ZnSiSe4 belong to the adamantine family of quaternary chalcogenides crystallizing in the wurtzstannite structure. Recent ab-initio calculations show, that the lowest energy structure of Cu2ZnSiSe4 is the wurtzkesterite type structure in contrast to wurtzstannite type, usually obtained in experiments. To clarify this issue a structural study on s...

Bulk crystals of Cu2ZnSiTe4 (CZSiTe) have been prepared by modified Bridgman method and have been investigated by single crystal X-ray method, Energy Dispersive X-Ray analysis and Raman scattering techniques. The structural studies revealed that the CZSiTe compounds crystallizes in the tetragonal space group , with a = b = 5.9612(1) Å and c = 11.78...

Cu 2 ZnSnS 4 thin films were grown by the spray pyrolysis method and annealed in an evacuated ampoule in presence of elemental sulfur. Annealing led to a significant decrease of the conductivity (by more than three orders of magnitude at room temperature). Transport properties are governed by the Mott variable-range hopping conduction mechanism in...

The Cu 2 ZnSnS 4 (CZTS) thin films were prepared by spray pyrolysis method at ambient pressure. Subsequent annealing of the CZTS layers in vapors of elemental selenium allowed to prepare the Cu 2 ZnSn(S x Se 1-x) 4 (CZTSSe) solid solutions. The energy dispersive X-ray analysis as well as Raman scattering investigation confirmed the formation of sol...

Using spectroscopic ellipsometry we investigated and analyzed the pseudo-optical constants of Cu2ZnSnSe4 bulk crystals, grown by the Bridgman method, over 0.8–4.5 eV photon energy range. The structures found in the spectra of the complex pseudodielectric functions were associated to E0, E1A, and E1B interband transitions and were analyzed in frame...

The vibrational properties of the wurtzstannite Cu2ZnGeS4 are studied experimentally by polarized Raman scattering in off-resonant and resonant conditions and theoretically by ab initio lattice dynamics calculations. Twenty-nine modes from 45 Raman active theoretically predicted have been experimentally detected and identified, including polar A1(T...

Resistivity, rho(T), of as-grown and annealed Cu2ZnSnS4 films, obtained by flash evaporation, is investigated between T similar to 10 and 300 K. A correlation between the transport properties and the growth conditions of the thin films is also explored. The behavior of rho(T) in the as-grown films exhibits a close proximity to the metal-insulator t...

Exciton spectra are studied in Cu2ZnSiSe4 single crystals at 10 and 300 K by means of reflection spectroscopy. The exciton parameters, dielectric constant and free carriers effective masses are deduced from experimental spectra by calculations in the framework of a model taking into account the spatial dispersion and the presence of a dead-layer. T...

The polarized Raman spectra of the Cu2ZnSnSe4 and Cu2ZnGeSe4 single crystals were measured for various in-plane rotation angles on the basal (1 1 2) crystal facet. The position of up to 15 (for Cu2ZnSnSe4) and 16 (for Cu2ZnGeSe4) Raman peaks was determined in the spectral region 50–300 cm-1. From the analysis of the experimental dependence of the i...

The polarized Raman spectra of the Cu2ZnSiS4 and Cu2ZnSiSe4 single crystals were investigated as a function of the in-plane rotation angle on the basal (210) crystal planes. The position of up to 32 (for the sulphide compound) and 27 (for the selenide compound) Raman peaks was determined for each of the compounds in the spectral region 50–600 cm-1....

We report the room temperature spectroscopic ellipsometry study of Cu2ZnGeSe4 and Cu2ZnSiSe4 crystals, grown by modified Bridgman technique. Optical measurements were performed in the range 1.2-4.6 eV. The spectral dependence of the complex pseudodielectric functions as well as pseudo-complex refractive index, extinction coefficient, absorption coe...

Optical properties of the Cu2ZnGeS4 bulk single crystals were characterized by using Raman spectroscopy and photoluminescence spectroscopy technique. The strongest lattice vibration mode of this compound observed at 359 cm-1 and less intensive modes at 273, 291, 332, 370, 383, 405 and 414 cm-1. PL spectra of the Cu2ZnGeS4 consist of dominant broad...

Wurtzstannite-type Cu2ZnGeS4, Cu2ZnSiSe4 and Cu2ZnSiS4 single crystals were grown by chemical vapor transport method using iodine as transport agent. Raman spectra of obtained crystals were investigated and 17, 11 and 18 peaks were observed for Cu2ZnGeS4, Cu2ZnSiSe4 and Cu2ZnSiS4, respectively. In all cases, the spectra from these compounds are cha...

Spectroscopic ellipsometry has been used to characterize the dielectric functions of bulk Cu2SnSe3 crystals, grown by modified Bridgman technique. Spectral measurements were performed at room temperature over the energy range 1.0 to 4.7 eV. The spectral dependence of the complex dielectric functions, complex refractive index, the absorption coeffic...

Resistivity, ρ(T), in single crystals of p-Cu2ZnSnS4 is investigated in the temperature interval of T∼300−10 K. Below ∼200 K, ρ(T) exhibits an activated character obeying between ∼130−150 K and ∼30−70 K the Mott variable-range hopping conduction law. Analysis of the experimental data yields typical values of the relative acceptor concentration, N/N...

Cu2ZnSnS4 (CZTS) thin films were deposited on glass substrates by spray pyrolysis a fast, cost effective and vacuum-free method. X-ray fluorescence, Raman spectroscopy and grazing incidence X-ray diffraction, were used to characterize the obtained thin films. The analysis of these data showed a close to stoichiometry composition of the films and CZ...

Spinel-type MnxFe1−xIn2S4 solid solutions grown by the planar melt crystallization method (the horizontal version of the Bridgman method) are investigated by means of energy dispersive X-ray analysis and Raman scattering spectroscopy for x values from 0 to 1. The distribution of cations in octahedral and tetrahedral sites of the spinel structure is...

Cu2ZnSnS4 single crystals prepared by the chemical vapor transport technique were investigated by x-ray diffraction, chemical microprobe analysis, and Raman and photoluminescence spectroscopies. Single-crystal x-ray measurements show that Cu2ZnSnS4 crystallizes in the kesterite structure with the space group I4̅ and unit cell parameters a = 5.4174(...

Magnetotransport of individual rolled-up Fe(3)Si nanomembranes is investigated in a broad temperature range from 4.2 K up to 300 K in pulsed magnetic fields up to 55 T. The observed magnetoresistance (MR) has the following pronounced features: (i) MR is negative in the investigated intervals of temperature and magnetic field; (ii) its magnitude inc...

Single crystals of Cu2ZnSn(SxSe1−x)4 (CZTSSe) solid solutions were grown by chemical vapor transport technique using iodine trichloride as a transport agent. As confirmed by X-ray investigations, the as-grown CZTSSe solid solutions are single phase and crystallized in kesterite structure. The lattice parameters of CZTSSe were determined and the S c...

Photoluminescence (PL) and Raman scattering were used to characterize the single crystals of Cu2ZnSiQ4 (Q = S, Se). Thin-blade single crystals of Cu2ZnSiQ4 were grown by chemical vapor transport technique using iodine as a transport agent. PL spectrum of Cu2ZnSiS4 showed several near-band-edge emission lines and two broad bands at lower energy side...

MnIn2S4 single crystals grown by the directional crystallization method were investigated by using the temperature and excitation power dependencies of photoluminescence (PL) spectra. PL spectra consist of one broad band resulting from donor-acceptor pair recombination. The analysis of the temperature quenching of the PL intensity yields one defect...

We show that the temperature-dependent resistivity ρ(T), Hall number n H(T) and the cotangent of the Hall angle cot θ H(T) of Ba(Fe1−x Co x )As2 (x=0.0–0.2) can be scaled using a recently proposed model-independent scaling method (Luo et al. in Phys. Rev. B 77:014529, 2008). The zero field normal-state resistivity above T c can be reproduced by the...

In various electron-doped Ba(Fe1 − xCox)2As2 (x = 0–0.3) and hole-doped Ba1 − xKxFe2As2 (x = 0–1) members of the 122-iron-pnictide superconductor family, the temperature-dependent resistivity ρ can be scaled into a universal curve. It is found that the ρ(T) dependences can be reproduced by the formulae and in the case of electron and hole doping, r...

Resistivity, ρ(T), of the amorphous RexSi1−x thin films with x = 0.285–0.351 is investigated in the interval of T ~ 300–0.03 K. At x = 0.285–0.324 the activated behavior of ρ(T) is governed by the Mott and the Shklovskii–Efros variable-range hopping (VRH) conduction mechanisms in different temperature intervals and the three-dimensional regime of t...

Device-grade ternary Cu–Ga–Se chalcopyrite thin films used for photovoltaic energy conversion have been prepared by a novel chemical close-spaced vapor transport (CCSVT) technique developed for a deposition on areas of up to 10×10 cm2. A two-step process has been developed which allows the fine tuning of the film composition and the electronic prop...

Polarization-dependent absorption characterization of Cu2ZnSiQ4 (Q=S, Se) quaternary single crystal compound semiconductors were carried out in the temperature range of 10–300K. The absorption measurements were performed on the as grown basal plane with the normal along [210] and the axis c parallel to the long edge of the crystal platelet. A signi...

We show that the zero-field normal-state resistivity of temperature-dependent resistivity ρ(T) of SrFe2−xNixAs2 can be reproduced by the expression ρ(T) = ρ0 + cT exp(−2Δ/T). ρ(T) can be scaled using both this expression where the energy scale Δ, c and the residual resistivity ρ0 are scaling parameters and a recently proposed model-independent scal...

A comparative study of chalcopyrite-related Cu2In7Se11.5 and CuIn5Se8 crystals by spectroscopic ellipsometry is presented. Their complex dielectric function ɛ(ω) = ɛ1(ω) + iɛ2(ω) has been determined in the 0.8–4.7 eV photon energy range. The spectral dependence of ɛ1(ω) and ɛ2(ω) as well as the complex refractive index, the absorption coefficient a...

Non-equilibrium ion implantation of Ge in p-type polycrystalline thin film CuGaSe2 (CGSe) prepared by Chemical Close-spaced Vapor Transport (CCSVT) has been performed with the goal to achieve n-type doping of this chalcopyrite semiconductor. Using Electron Spin Resonance (ESR) it is shown that Ge implantation induces a paramagnetic species at g = 2...

We show that the zero field normal-state resistivity above Tc for various levels of electron doping - both for LaO1-xFxFeAs (La-1111) and SmO1-xFxFeAs (Sm-1111) members of the 1111-iron-pnictide superconductor family - can be scaled in a broad temperature range from 20 to 300 K onto single curves for underdoped La-1111 (x=0.05-0.075), for optimally...

The dielectric functions of Cu ₂ ZnGeS ₄ bulk crystals grown by the Bridgman method were measured over the energy range 1.4 to 4.7 eV at room temperature using variable angle spectroscopic ellipsometry. The observed structures in the dielectric functions were adjusted using the Adachi’s model and attributed to interband transi...

In this study, anisotropic near band edge transitions of Cu2ZnSiS4 single crystals grown by chemical vapor transport were characterized by using polarization-dependent absorption, piezoreflectance (PzR) and surface photovoltage (SPV) spectroscopy techniques at room temperature. The measurements were carried out on the as grown basal plane with the...

Single crystals of CuGaS2 have been grown by chemical vapour transport. Their near-band gap photoluminescence properties were investigated in the temperature range of 10–300 K. The variation of the exciton gap energy with temperature was studied by means of a three-parameter thermodynamic model, the Einstein model and the Pässler model. Values of t...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The temperature dependence of the band-edge excitonic transitions of Cu2ZnSiS4 single crystals were characterized by using polarization-dependent piezoreflectance (PzR) in the temperature range of 10-300 K. The PzR measurements were carried out on the as-grown basal plane with the normal along [2 1 0] and the c axis parallel to the long edge of the...

We present here a complementary study on germanium doping of the wider-band-gap CuGaSe2 (CGS) chalcopyrite. In photoluminescence studies, the occurrence of a new emission line was identified as Ge related and explained as a donor-acceptor-pair recombination. The precise role the Ge is playing in this doping of CGS is revealed by x-ray absorption sp...

We show that the zero field normal-state resistivity above Tc for various levels of electron doping-both for underdoped, optimally, and overdoped LaO1-xFxFeAs, i.e. (x=0.05-0.075 and 0.1-0.2) and underdoped SmO1-xFxFeAs (x=0.06- 0.1) members of the 1111-iron-pnictide superconductor family-can be scaled in a broad temperature range from 20 to 300 K...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Spectroscopic ellipsometry has been used to characterize the dielectric functions of bulk Cu ( In _{1- x} Ga _x)₅ Se ₈ crystals. Spectra were measured at room temperature over the energy range 0.74–5.2 eV. The dielectric functions as well as the complex refractive index, the absorption coefficient, and the...

Spectroscopic ellipsometry has been used to characterize the dielectric functions of bulk CuIn 1−x Ga x 5 Se 8 crystals. Spectra were measured at room temperature over the energy range 0.74–5.2 eV. The dielectric functions as well as the complex refractive index, the absorption coefficient, and the normal-incidence reflectivity have been modeled us...

We report B_c2 data for LaO_{0.9}F_{0.1}FeAs_{1-delta} in a wide T and field range up to 60 Tesla. The large slope of B_c2 approx ~ -6 Tesla/K near an improved T_c = 28.5 K of the in-plane B_c2(T) contrasts with a flattening starting at 23 K above 30 Tesla we regard as the onset of Pauli-limited behavior (PLB) with B_c2(0) about 65 Tesla. We interp...

This paper presents results on the preparation, structural, electrical and magnetic properties of Fe(3)Si films as a representative for a Heusler alloy-like compound which are known as half-metallic materials with ferromagnetic behaviour. The films have been prepared by means of ultra-high vacuum (UHV) electron beam evaporation with the aim of achi...

Spectroscopic ellipsometry has been used to characterize the dielectric functions of bulk CuIn 1−x Ga x 5 Se 8 crystals. Spectra were measured at room temperature over the energy range 0.74–5.2 eV. The dielectric functions as well as the complex refractive index, the absorption coefficient, and the normal-incidence reflectivity have been modeled us...

Polycrystalline samples of CuGaSe2-related defect compounds (DC) have been prepared by Chemical Close-Spaced Vapour Transport (CCSVT) (thin films) and elemental synthesis (powder) respectively. In the latter case a homogenisation step was introduced during the preparation, including mechanical intermixing and adjacent-heat treatment after the main...

The dielectric functions ϵ(ω) = ϵ1(ω) +i ϵ2(ω) of CuIn1+2nSe2+3n and CuGa1+2nSe2+3n (n = 2.5, 3.0, 3.5) have been determined in the photon energy range from 0.8 to 4.7 eV by spectroscopic ellipsometry. The measurements reveal distinct structures at energies of the critical points in the Brillouin zone. The structure observed in the spectral depende...

We report B_c2 data for LaO_{0.9}F_{0.1}FeAs_{1-delta} in a wide T and field range up to 60 Tesla. The large slope of B_c2 approx ~ -6 Tesla/K near an improved T_c = 28.5 K of the in-plane B_c2(T) contrasts with a flattening starting at 23 K above 30 Tesla we regard as the onset of Pauli-limited behavior (PLB) with B_c2(0) about 65 Tesla. We interp...

Optical measurements of Cu(In1–xGax)5Se8 were performed at room temperature in the photon energy range from 0.8 to 4.7 eV. Spectral dependence of the complex dielectric functions was derived. The structures observed in the measured spectra have been analyzed by fitting the second derivative of the experimental spectrum to analytical line shapes and...

Resistivity, ρ (T), of the spin-ladder compound CaCu2O3 is investigated between T ~ 100 − 350 K. Both nearest-neighbor hopping, ρ (T) ~ exp (Ea/kT), and variable-range hopping, ρ (T) ~ exp [(T0/T)3/4 ], quasi one-dimensional conductivity mechanisms are observed above and below T ~ 200 K, respectively. The activation energy Ea and the VRH charac...

Resistivity measurements of Mn-doped p-type β-FeSi2 single crystals are presented and analyzed with the different hopping conductivity models. Both the Mott and the Shklovskii- Efros regimes of the variable-range hopping (VRH) conductivity are observed as well as the universal scaling behavior of the resistivity. The characteristic and transition t...

Analysis of the optical properties of bulk Cu ( In _1-x Ga _x)₃ Se ₅ mixed crystals synthesized from the elements as a function of the Ga content is presented. Measurements of the complex dielectric function ε(ω)=ε₁(ω)+iε₂(ω) were performed at room temperature in the photon energy rang...

The paper presents resistivity and magnetization measurements on nearly stoichiometric Fe ₃ Si films epitaxially grown on GaAs substrates by electron-beam evaporation in an ultrahigh vacuum chamber. In the low-temperature resistivity a T³ term was found in all samples. A term like that is known to describe the anomalous single...

The article gives a report on resistivity measurements on Mn-doped p -type FeSi ₂ single crystals and analyzes the data within the framework of different hopping conductivity models. Both the Mott [N. Mott and E. A. Davies, Electron Processes in Non-Crystalline Materials (Clarendon, Oxford, 1979)] and the Shklovskii–Efros [B. I. Shklovsk...

The resistivity ρ(T) of the spin-ladder compound CaCu ₂ O ₃ measured along the Cu–O–Cu leg ( j || b ) exhibits a strongly activated character. It increases from ∼10⁴ to ∼10⁹ Ω  m if T decreases from 350 to 100 K. The charge transfer above T∼200 K is governed by a quasi-one-dimensional (1D) nearest-neighbo...

The complex dielectric functions, ε(ω)=ε₁(ω)+iε₂(ω) , of CuIn ₃ Se ₅ and CuIn ₅ Se ₈ crystals with different Cu contents have been determined in the 0.8–4.7 eV photon energy range by using spectroscopic ellipsometry. The spectral dependence of the real, ε₁(ω) , and imagina...

Photoreflectivity, wavelength modulation spectroscopy and photoluminescence measurements of CuGaSe(2) are used to determine the exciton and band parameters as well as the energy band structure of CuGaSe2 at photon energies higher than the fundamental band gap. The spectral dependences of the real epsilon(1) and imaginary epsilon(2) components of th...

Spectral dependence of the real epsilon(1)(omega) and imaginary epsilon(2)(omega) parts of the complex dielectric function, complex refractive index, absorption coefficient, and normal-incidence reflectivity of CuGa5Se8 crystals with slightly different Cu contents are modeled using Adachi's model for interband transitions. The results are in good a...

The reflection spectroscopy of chalcopyrite CuGaS2 and CuInS2 single crystals has been applied for light polarized perpendicular () and parallel () to the optical axis in the photon energy range between 1.5 and 6 eV at 77 K. By using the Kramers–Kronig relations, the spectral dependences of the real ε1 and imaginary ε2 components of the complex die...

We have investigated the magnetic properties of the Heusler phase Co2Cr1-xFeAl in the composition regime (x=0.3-0.5) in the disordered B2 phase. Both bulk and surface static and dynamic magnetic aspects were addressed by employing alternating gradient magnetometry (AGM), magneto-optical Kerr effect (MOKE) and Brillouin light scattering (BLS). All s...