A. Sirenko - Academia.edu (original) (raw)
Papers by A. Sirenko
We discovered that perovskite (Ba,La)SnO3 can have excellent carrier mobility even though its ban... more We discovered that perovskite (Ba,La)SnO3 can have excellent carrier mobility even though its band gap is large. The Hall mobility of Ba0.98La0.02SnO3 crystals with the n-type carrier concentration of \sim 8-10\times10 19 cm-3 is found to be \sim 103 cm2 V-1s-1 at room temperature, and the precise measurement of the band gap \Delta of a BaSnO3 crystal shows \Delta=4.05 eV, which is significantly larger than those of other transparent conductive oxides. The high mobility with a wide band gap indicates that (Ba,La)SnO3 is a promising candidate for transparent conductor applications and also epitaxial all-perovskite multilayer devices.
We study the performance of a commercial bidirectional Quantum Key Distribution system in the pre... more We study the performance of a commercial bidirectional Quantum Key Distribution system in the presence of a weak magnetic field (about 50 µT) applied along the fiber axis. We observe a quadratic increase in quantum bit error rate with the angle of Faraday rotation. . Introduction Quantum Key Distribution (QKD) exploits the quantum-mechanical properties of light to generate identical pairs of random secret keys for two parties connected by an optical fiber. The entire QKD field surged recently and has already reached its first commercial offerings [1]. While integration of these QKD systems into real networks remains challenging, their range of applicability is of interest to service providers. Both commercially available systems utilize bidirectional technology [2], in which the key is encoded in a photon phase, and polarization effects in the fiber are selfcompensated with a Faraday mirror at one end. The detailed explanation of such scheme can be found elsewhere [3]. Briefly, two ...
Introduction: Optical communication systems operating at 10 Gbit=s are becoming increasingly impo... more Introduction: Optical communication systems operating at 10 Gbit=s are becoming increasingly important even for short reach applications such as metro, access and data-link networks. In fact, approximately 40% of all commercial 10 Gbit=s interfaces to be deployed between 2003 and 2006 are expected to be short reach (<2 km) [1]. A key enabling technology for the development of such systems is a reliable, high-speed optical transmitter that can be produced at low cost. In this respect, directly modulated semiconductor Fabry–Perot lasers offer several advantages over DFB lasers, including higher yield and no need for optical isolators. Uncooled operation is required to further reduce the transmitter cost, size, and power consumption, which requires laser devices capable of maintaining a high level of performance over a wide temperature range. For high-temperature operation, use of an InGaAlAs multiquantum-well (MQW) active material is advantageous [2], primarily because of its large...
ECS Meeting Abstracts
not Available.
MRS Proceedings
We report the experimental studies of the vibrational spectra of SrTiO3 films with the thickness ... more We report the experimental studies of the vibrational spectra of SrTiO3 films with the thickness of 1 µm grown by pulsed laser deposition. Fourier-transform infrared ellipsometry between 30 and 700 cm−1 and electric field-induced Raman scattering have been utilized for investigation of the phonon behavior. These results can be used for comparison with the low-frequency measurements of the static dielectric constant. In the films, the soft mode reveals hardening compared to that in bulk crystals. This observation is in agreement with the Lyddane-Sachs-Teller formalism.
AIP Conference Proceedings
Superlattices and Microstructures, 2006
ABSTRACT The discovery of the intriguing phase diagram of Ca3(Ru1-xTix)2O7 is the new and excitin... more ABSTRACT The discovery of the intriguing phase diagram of Ca3(Ru1-xTix)2O7 is the new and exciting development in correlated electron ruthenates, as Ti doping drastically changes the material's ground state properties. The undoped Ca3Ru2O7 is metallic at high temperature and undergoes an antiferromagnetic transition at 56 K that is followed by a metal-insulator transition at 48 K driven by the opening of a charge density wave gap. A quasi-2D metallic state develops below 30 K. At 5% Ti doping, the metal-insulator transition temperature is TMI=80 K, below which the material is a Mott insulator. By contrast, a weakly localized electronic state is observed at intermediate dopings (2-4% Ti) together with antiferromagnetic long range order. In the undoped Ca3Ru2O7, the metal-insulator transition at 48 K is accompanied by the development of a charge gap below 200 cm-1. At low temperatures, a small Drude peak develops below 50 cm-1, resulting from small non-nested metallic pockets of the Fermi surface. We report a far-infrared spectroscopic ellipsometry study of Ca3(Ru1-xTix)2O7 (x=0.03) at U4IR beamline of NSLS-BNL. Our data indicate that the low-temperature gap in optical conductivity opens at 1000 cm-1, a dramatically different value from the one in the undoped compound. We relate our observations to the effects of Ti doping - the induced changes in carrier itinerancy and the modified double-exchange and superexchange interactions in the material.
We report the experimental studies of the vibrational spectra of SrTiO 3 films with the thickness... more We report the experimental studies of the vibrational spectra of SrTiO 3 films with the thickness of 1 µm grown by pulsed laser deposition. Fourier-transform infrared ellipsometry between 30 and 700 cm-1 and electric field-induced Raman scattering techniques have been utilized for investigation of the phonon behavior. These results can be used for comparison with the low-frequency measurements of the static dielectric constant. The soft mode in the films reveals hardening compared to that in bulk crystals. This observation is in agreement with the Lyddane-Sachs-Teller formalism.
MRS Proceedings, 2008
ABSTRACTWe have observed gate-controlled N-shaped negative differential resistance (NDR) and phot... more ABSTRACTWe have observed gate-controlled N-shaped negative differential resistance (NDR) and photoconductivity enhancement in carbon nanotube (CNT) based addressable intra-connects. The intra-connects – bridges spanning across planar electrodes – were measured at room temperature. Individual single-walled CNT (SWCNT) channels were grown using chemical vapor deposition (CVD) precisely between very sharp metal tips on the pre-fabricated electrodes without post-processing. The electrodes were made of cobalt. Methane and H2 gas mixture were introduced into quartz tube for an hour at 900 C, with flow rate of 1900 sccm for methane and 20 sccm for H2. We have investigated two different cases: in one case, the source-drain current-voltage, Ids-Vds, characteristics were linear. The other case exhibited nonlinear Ids-Vds characteristics. Raman scattering of the intra-connects indicated that each were made of SWCNT with radial breathing mode (RBM) at 191.9 cm-1 and 176.2 cm-1, respectively. Cu...
Post-focusing collimating optics are introduced as a tool to condition X-ray microbeams for the u... more Post-focusing collimating optics are introduced as a tool to condition X-ray microbeams for the use in high-resolution X-ray diffraction and scattering techniques. As an example, a one-bounce imaging capillary and miniature Si(004) channel-cut crystal were used to produce a microbeam with 10 mum size and an ultimate angular resolution of 2.5 arc sec. This beam was used to measure the strain in semiconductor microstructures by using X-ray high resolution diffraction and standing wave techniques to Deltad/d < 5×10-4.
Physical Review Letters, 2000
Physical Review B, 2008
Linearly polarized spectra of far-infrared ͑IR͒ transmission in HoMn 2 O 5 multiferroic single cr... more Linearly polarized spectra of far-infrared ͑IR͒ transmission in HoMn 2 O 5 multiferroic single crystals have been studied in the frequency range between 8.5 and 105 cm −1 and for temperatures between 5 and 300 K. Polarization of IR-active excitations depends on the crystallographic directions in HoMn 2 O 5 and is sensitive to the magnetic phase transitions. We attribute some of the infrared-active excitations to electric-dipole transitions between ligand-field ͑LF͒ split states of Ho 3+ ions. For light polarization along crystalline b axis, the oscillator strength of electric dipoles at low frequencies ͑10.5, 13, and 18 cm −1 ͒ changes significantly at the commensurate-incommensurate antiferromagnetic phase transition at T 3 = 19 K. This effect shows a strong correlation with the pronounced steps of the b-directional static dielectric function. We propose that the LF on Ho 3+ connects the magnetism and dielectric properties of this compound through coupling with the Mn spin structure. We comment on the possibility for composite excitations of magnons and excited LF states.
We discovered that perovskite (Ba,La)SnO3 can have excellent carrier mobility even though its ban... more We discovered that perovskite (Ba,La)SnO3 can have excellent carrier mobility even though its band gap is large. The Hall mobility of Ba0.98La0.02SnO3 crystals with the n-type carrier concentration of \sim 8-10\times10 19 cm-3 is found to be \sim 103 cm2 V-1s-1 at room temperature, and the precise measurement of the band gap \Delta of a BaSnO3 crystal shows \Delta=4.05 eV, which is significantly larger than those of other transparent conductive oxides. The high mobility with a wide band gap indicates that (Ba,La)SnO3 is a promising candidate for transparent conductor applications and also epitaxial all-perovskite multilayer devices.
We study the performance of a commercial bidirectional Quantum Key Distribution system in the pre... more We study the performance of a commercial bidirectional Quantum Key Distribution system in the presence of a weak magnetic field (about 50 µT) applied along the fiber axis. We observe a quadratic increase in quantum bit error rate with the angle of Faraday rotation. . Introduction Quantum Key Distribution (QKD) exploits the quantum-mechanical properties of light to generate identical pairs of random secret keys for two parties connected by an optical fiber. The entire QKD field surged recently and has already reached its first commercial offerings [1]. While integration of these QKD systems into real networks remains challenging, their range of applicability is of interest to service providers. Both commercially available systems utilize bidirectional technology [2], in which the key is encoded in a photon phase, and polarization effects in the fiber are selfcompensated with a Faraday mirror at one end. The detailed explanation of such scheme can be found elsewhere [3]. Briefly, two ...
Introduction: Optical communication systems operating at 10 Gbit=s are becoming increasingly impo... more Introduction: Optical communication systems operating at 10 Gbit=s are becoming increasingly important even for short reach applications such as metro, access and data-link networks. In fact, approximately 40% of all commercial 10 Gbit=s interfaces to be deployed between 2003 and 2006 are expected to be short reach (<2 km) [1]. A key enabling technology for the development of such systems is a reliable, high-speed optical transmitter that can be produced at low cost. In this respect, directly modulated semiconductor Fabry–Perot lasers offer several advantages over DFB lasers, including higher yield and no need for optical isolators. Uncooled operation is required to further reduce the transmitter cost, size, and power consumption, which requires laser devices capable of maintaining a high level of performance over a wide temperature range. For high-temperature operation, use of an InGaAlAs multiquantum-well (MQW) active material is advantageous [2], primarily because of its large...
ECS Meeting Abstracts
not Available.
MRS Proceedings
We report the experimental studies of the vibrational spectra of SrTiO3 films with the thickness ... more We report the experimental studies of the vibrational spectra of SrTiO3 films with the thickness of 1 µm grown by pulsed laser deposition. Fourier-transform infrared ellipsometry between 30 and 700 cm−1 and electric field-induced Raman scattering have been utilized for investigation of the phonon behavior. These results can be used for comparison with the low-frequency measurements of the static dielectric constant. In the films, the soft mode reveals hardening compared to that in bulk crystals. This observation is in agreement with the Lyddane-Sachs-Teller formalism.
AIP Conference Proceedings
Superlattices and Microstructures, 2006
ABSTRACT The discovery of the intriguing phase diagram of Ca3(Ru1-xTix)2O7 is the new and excitin... more ABSTRACT The discovery of the intriguing phase diagram of Ca3(Ru1-xTix)2O7 is the new and exciting development in correlated electron ruthenates, as Ti doping drastically changes the material's ground state properties. The undoped Ca3Ru2O7 is metallic at high temperature and undergoes an antiferromagnetic transition at 56 K that is followed by a metal-insulator transition at 48 K driven by the opening of a charge density wave gap. A quasi-2D metallic state develops below 30 K. At 5% Ti doping, the metal-insulator transition temperature is TMI=80 K, below which the material is a Mott insulator. By contrast, a weakly localized electronic state is observed at intermediate dopings (2-4% Ti) together with antiferromagnetic long range order. In the undoped Ca3Ru2O7, the metal-insulator transition at 48 K is accompanied by the development of a charge gap below 200 cm-1. At low temperatures, a small Drude peak develops below 50 cm-1, resulting from small non-nested metallic pockets of the Fermi surface. We report a far-infrared spectroscopic ellipsometry study of Ca3(Ru1-xTix)2O7 (x=0.03) at U4IR beamline of NSLS-BNL. Our data indicate that the low-temperature gap in optical conductivity opens at 1000 cm-1, a dramatically different value from the one in the undoped compound. We relate our observations to the effects of Ti doping - the induced changes in carrier itinerancy and the modified double-exchange and superexchange interactions in the material.
We report the experimental studies of the vibrational spectra of SrTiO 3 films with the thickness... more We report the experimental studies of the vibrational spectra of SrTiO 3 films with the thickness of 1 µm grown by pulsed laser deposition. Fourier-transform infrared ellipsometry between 30 and 700 cm-1 and electric field-induced Raman scattering techniques have been utilized for investigation of the phonon behavior. These results can be used for comparison with the low-frequency measurements of the static dielectric constant. The soft mode in the films reveals hardening compared to that in bulk crystals. This observation is in agreement with the Lyddane-Sachs-Teller formalism.
MRS Proceedings, 2008
ABSTRACTWe have observed gate-controlled N-shaped negative differential resistance (NDR) and phot... more ABSTRACTWe have observed gate-controlled N-shaped negative differential resistance (NDR) and photoconductivity enhancement in carbon nanotube (CNT) based addressable intra-connects. The intra-connects – bridges spanning across planar electrodes – were measured at room temperature. Individual single-walled CNT (SWCNT) channels were grown using chemical vapor deposition (CVD) precisely between very sharp metal tips on the pre-fabricated electrodes without post-processing. The electrodes were made of cobalt. Methane and H2 gas mixture were introduced into quartz tube for an hour at 900 C, with flow rate of 1900 sccm for methane and 20 sccm for H2. We have investigated two different cases: in one case, the source-drain current-voltage, Ids-Vds, characteristics were linear. The other case exhibited nonlinear Ids-Vds characteristics. Raman scattering of the intra-connects indicated that each were made of SWCNT with radial breathing mode (RBM) at 191.9 cm-1 and 176.2 cm-1, respectively. Cu...
Post-focusing collimating optics are introduced as a tool to condition X-ray microbeams for the u... more Post-focusing collimating optics are introduced as a tool to condition X-ray microbeams for the use in high-resolution X-ray diffraction and scattering techniques. As an example, a one-bounce imaging capillary and miniature Si(004) channel-cut crystal were used to produce a microbeam with 10 mum size and an ultimate angular resolution of 2.5 arc sec. This beam was used to measure the strain in semiconductor microstructures by using X-ray high resolution diffraction and standing wave techniques to Deltad/d < 5×10-4.
Physical Review Letters, 2000
Physical Review B, 2008
Linearly polarized spectra of far-infrared ͑IR͒ transmission in HoMn 2 O 5 multiferroic single cr... more Linearly polarized spectra of far-infrared ͑IR͒ transmission in HoMn 2 O 5 multiferroic single crystals have been studied in the frequency range between 8.5 and 105 cm −1 and for temperatures between 5 and 300 K. Polarization of IR-active excitations depends on the crystallographic directions in HoMn 2 O 5 and is sensitive to the magnetic phase transitions. We attribute some of the infrared-active excitations to electric-dipole transitions between ligand-field ͑LF͒ split states of Ho 3+ ions. For light polarization along crystalline b axis, the oscillator strength of electric dipoles at low frequencies ͑10.5, 13, and 18 cm −1 ͒ changes significantly at the commensurate-incommensurate antiferromagnetic phase transition at T 3 = 19 K. This effect shows a strong correlation with the pronounced steps of the b-directional static dielectric function. We propose that the LF on Ho 3+ connects the magnetism and dielectric properties of this compound through coupling with the Mn spin structure. We comment on the possibility for composite excitations of magnons and excited LF states.