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1

Spectra of Wideband Dipole Radiation Induced by the Photomagnetoelectric Response in Narrow Gap Semiconductors

100%

Kiprijanovič O., Shatkovskis E., Kiprijanovič L.

Acta Physica Polonica A

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2008

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vol. 114

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issue 4

761-767

EN

The frequency spectra of sign inverted photomagnetoelectric responses in narrow gap semiconductors InSb, InAs, and Cd_{0.2}Hg_{0.8}Te, excited by nanosecond laser light pulses, were used for calculation of induced electromagnetic radiation frequency spectra in dipole approximation. The parallelepiped shape sample was considered as capacitor-like point dipole. The known Fourier transform property was used in calculations. Features of double sign inverted signals formation and its spectra are considered and compared with experimental results. The radiation of pulses, having spectra in terahertz range when excited by picosecond laser pulse from capacitor-like radiators that demonstrate double sign inverted photoresponses, is expected.

2

Hot-Phonon Decided Carrier Velocity in AlInN/GaN Based Two-Dimensional Channels

100%

Ardaravičius L., Kiprijanovič O., Liberis J.

Acta Physica Polonica A

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2011

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vol. 119

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issue 2

231-233

EN

Nanosecond-pulsed measurements of hot-electron transport were performed for a nominally undoped two-dimensional channel confined in a slightly strained Al_{0.8}In_{0.2}N/AlN/GaN and nearly lattice matched Al_{0.84}In_{0.16}N/AlN/GaN heterostructures at room temperature. No current saturation is reached because we minimized the effect of the Joule heating. The electron drift velocity is deduced under assumption of uniform electric field and field-independent electron density. The estimated drift velocity ≈ 1.5 × 10^7 cm/s at 140 kV/cm bodes well with the value of hot-phonon lifetime exceeding 0.1 ps.

3

Ultrahigh Frequency Components in the Hot Electron Photomagnetoelectric Response of Strongly Photoexcited Narrow-Gap Semiconductors

100%

Shatkovskis E., Galickas A., Kiprijanovič O.

Acta Physica Polonica A

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2005

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vol. 107

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issue 2

271-274

EN

A photomagnetoelectric effect has been investigated in semiconductors InAs and Cd_xHg_{1-x}Te (x=0.2 and 0.26) excited by Q-switched neodymium-YAG laser. The photomagnetoelectric signal undergos double-sign-inversion when the intensity of the exciting light pulses exceeds a critical value I_c=5×10^{24} photons/(cm^2 s) for InAs and (1-4)×10^{24} photons/(cm^2 s) for Cd_xHg_{1-x}Te samples. It is shown that a frequency spectrum of photomagnetoelectric response is broadened significantly in the region of high frequencies. In general three frequency bands were distinguished. From this investigation it follows that using laser pulses of a duration t_{opt} 1-10 ps the photomagnetoelectric signal in the terahertz range may be generated.

4

Applicable Damage of High-T_{ rm c} YbaCuO Superconducting Tapes by Current and Laser Pulses

100%

Kiprijanovič O., Ašmontas S., Anisimovas F., Gradauskas J.

Acta Physica Polonica A

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2011

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vol. 119

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issue 2

256-258

EN

Damage and irreversible damage of YBaCuO tapes with high density current after switching from superconducting to normal state are investigated. Quasi-homogeneous current distribution across the tape in superconducting state can cause perfect tape damage or irreversible damage when current is slightly above critical value. The model of the tape heating during the optically initiated switching from superconducting to normal state is proposed. Analysis of causes inducing damage shows necessity to consider 0.5T_{m} damage criterion because of strong current influence on the damage processes. Possible damage mechanisms are described and crack tips motion simultaneously with switching from superconducting to normal state is considered. Application of optically illuminated YBaCuO tapes with nanosecond duration current pulses on the base of the described mechanisms is proposed.

5

The Electric Field and Temperature Dependence of Conductance of Two-Dimensional Electron Gas in AlGaN/AlN/GaN

100%

Ardaravičius L., Kiprijanovič O., Liberis J.

Acta Physica Polonica A

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2008

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vol. 113

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issue 3

1001-1004

EN

The two-dimensional gas in AlGaN/AlN/GaN heterostucture with a very thin (0.6 nm) AlN spacer was investigated by conductivity relaxation measurements in 86-300 K temperature range. The results show the presence of two exponential relaxation processes characterized by different characteristic time constants. Parameters of the fast and slow components of the processes differently depend on the electric field and temperature. The fast process is attributed to influence of the electric field on the barrier formed by the spacer, while the slow process is attributed to the hot-electron capture out of the channel followed by electron thermal release.

6

Hot-Electron Transport and Microwave Noise in 4H-SiC

88%

Ardaravičius L., Liberis J., Kiprijanovič O., Matulionienė I., Matulionis A.

Acta Physica Polonica A

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2005

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vol. 107

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issue 2

310-314

EN

Hot-electron transport and microwave noise are investigated for n-type 4H-SiC (n=2×10^{17} cm^{-3}) subjected to a pulsed electric field applied parallel to the basal plane. At room temperature, the negative differential conductance, masked by field ionization at the highest fields, is observed in the field range between 280 and 350 kV/cm. The threshold fields for the negative differential conductance and field ionization increase with lattice temperature. The results on microwave noise are used to evaluate the effective hot-electron temperature and the hot-electron energy relaxation time.

7

Reversible Resistive Switching in Electrically Nonhomogeneous La_{0.67}Ca_{0.33}MnO_3 Thin Films by Short Electrical Pulses

76%

Lučun A., Kiprijanovič O., Ašmontas S., Anisimovas F., Maneikis A., Sužied.lis A., Vengalis B.

Acta Physica Polonica A

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2008

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vol. 113

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issue 3

1059-1062

EN

Resistance changes in thin electrically nonhomogeneous La_{0.67}Ca_{0.33}MnO_3 films were investigated using electrical pulses of nanosecond duration in the 80-300 K temperature range. Two types of reversible switching to higher resistive states with different starting temperature induced by series of the positive pulses were observed. Possible mechanisms of the resistance switching by short electrical pulses in the vicinity of T_m and at 80-90 K are discussed.

8

Electroresistance of La-Ca-MnO Thin Films

64%

Cimmperman P., Stankevič V., Žurauskienė N., Balevičius S., Anisimovas F., Paršeliūnas J., Kiprijanovič O., Altgilbers L.

Acta Physica Polonica A

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2004

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vol. 105

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issue 1-2

107-114

EN

Epitaxial, textured, and polycrystalline La_{0.7}Ca_{0.3}Mn O_3 films, having about 150 nm thickness, were prepared by pulsed laser deposition techniques onto (110) NdGaO_3, MgO and lucalox substrates and investigated using 10 ns duration, 0.5 ns rise time electrical pulses having amplitude up to 500 V. Electroresistance of the films [R(E)-R(0)]/R(0) was investigated up to 80 kV/cm electric field strengths in temperatures ranging from 300 K to 4.2 K. Strong (up to 93%) negative electroresistance was obtained in polycrystalline La_{0.7}Ca_{0.3}MnO_3 films prepared on MgO and lucalox substrates. The epitaxial films grown on NdGaO_3 substrate demonstrated only a small resistance change due to Joule heating induced by a current pulse. It was concluded that electroresistance manifests itself in strongly inhomogeneous manganites films exhibiting a large number of structural imperfections producing ferromagnetic tunnel junction nets.

9

Fast Electrical Switching of Thin Manganite Films

64%

Balevičius S., Kiprijanovič O., Stankevič V., Žurauskienė N., Česnys A., Tolvaišienė S., Abrutis A., Plaušinaitienė V.

Acta Physica Polonica A

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2008

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vol. 113

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issue 3

821-824

EN

The effects of strong pulsed electric field on the electrical properties of thin epitaxial La_{0.7}Sr_{0.3}MnO_3 films were investigated. The fast electrical switching from high resistance off-state to low resistance on-state was obtained at current densities higher than 10^6 A/cm^2. This current was able to induce an irreversible damage of the sample in the regions at the edges of the electrodes of the film. It was demonstrated that thermal effects are responsible for appearance of delay time and asymmetrical shape of current channel in on-state, however, the fast switching from off- to on-state is a result of electronic effects appearing when critical power is reached in the film.

10

Electroresistance of Electrically Nonhomogeneous La_{0.67}Ca_{0.33}MnO_3/MgO Thin Films

64%

Kiprijanovič O., Lučun A., Ašmontas S., Anisimovas F., Butkutė R., Maneikis A., Sužiedėlis A., Vengalis B.

Acta Physica Polonica A

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2007

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vol. 111

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issue 1

141-146

EN

Current and electrical field-induced electroresistive effects were investigated for La_{0.67}Ca_{0.33}MnO_3/MgO thin films demonstrating nanosized electrical inhomogeneities. Two different models based on enhanced conductivity of intergrain boundaries by injecting spin-polarized carriers from ferromagnetic grains and electrical field-enhanced hopping of carriers in high resistance intergrain media were carried out to explain nonlinear electrical properties of the films.

11

Magnetoresistance of Polycrystalline La_{0.7}Ca_{0.3}MnO_3 Films in a Microwave Magnetic Field

64%

Lučun A., Butkutė R., Maneikis A., Kiprijanovič O., Anisimovas F., Gradauskas J., Sužiedėlis A., Vengalis B., Kancleris Ž., Ašmontas S.

Acta Physica Polonica A

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2007

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vol. 111

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issue 1

147-152

EN

We present new experimental evidence indicating the importance of magnetic field component of microwave field (f=9.4 GHz) for magnetoresistive properties of polycrystalline La_{0.7}Ca_{0.3}MnO_3 films. The microwave measurements revealed a different character of the temperature-dependent electrical resistance of polycrystalline La_{0.7}Ca_{0.3}MnO_3 films placed in the centre (maximal amplitude of H_{10} wave vector) and at a narrow wall of the wave-guide (reduced H_{10} amplitude). Theoretical estimations of the influence of substrate onto distribution of microwave electric and magnetic fields in the waveguide were performed using the finite-difference time-domain method.

Refine search results

Spectra of Wideband Dipole Radiation Induced by the Photomagnetoelectric Response in Narrow Gap Semiconductors

Hot-Phonon Decided Carrier Velocity in AlInN/GaN Based Two-Dimensional Channels

Ultrahigh Frequency Components in the Hot Electron Photomagnetoelectric Response of Strongly Photoexcited Narrow-Gap Semiconductors

Applicable Damage of High-T_{ rm c} YbaCuO Superconducting Tapes by Current and Laser Pulses

The Electric Field and Temperature Dependence of Conductance of Two-Dimensional Electron Gas in AlGaN/AlN/GaN

Hot-Electron Transport and Microwave Noise in 4H-SiC

Reversible Resistive Switching in Electrically Nonhomogeneous La_{0.67}Ca_{0.33}MnO_3 Thin Films by Short Electrical Pulses

Electroresistance of La-Ca-MnO Thin Films

Fast Electrical Switching of Thin Manganite Films

Electroresistance of Electrically Nonhomogeneous La_{0.67}Ca_{0.33}MnO_3/MgO Thin Films

Magnetoresistance of Polycrystalline La_{0.7}Ca_{0.3}MnO_3 Films in a Microwave Magnetic Field