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DOPC liposome properties of various sizes were analyzed via atomic force microscopy (AFM) and patch-clamp. The unilamellarity of small DOPC liposome (below 1 μm) was confirmed via Cryogenic transmission electron microscopy (Cryo-TEM). Small DOPC liposome (below 1 μm) showed a bending modulus (kbend) ranging (between 10−18 and 10−20 J). The bending modulus value was a size dependence. In order words, it decreased as DOPC liposome size increased. For DOPC liposome (above 1 μm), patch-clamp was used to achieve electrically tight whole-cell configurations. Our result showed that the unilamellar DOPC liposome (above 1 μm) exhibit RC circuit response property. It was similar to theoretical values (τ = 4.52 ms) of the unilamellar liposome. In this study, the uniform lamellarity of the DOPC liposome of various sizes was confirmed through electrical and mechanical properties of DOPC liposome.

Transition-metal-based nitrides and carbides have been widely studied for various applications because of their excellent mechanical, electrical, and catalytic properties. Although outstanding performances of Mo nitride and carbonitride synthesized by chemical reaction methods have been reported recently for catalytic applications, a metallic phase transition method for pre-deposited MoO3 precursor films, which is suitable for application to Si or metallic substrates, has rarely been reported. Herein, we investigate Mo nitride and carbonitride thin films synthesized via nitriding and carbonitriding of MoO3 films using two types of ammonium salt precursors, urea and ammonium carbonate (AC), in the chemical vapor deposition (CVD) process. The phase-changed crystalline films of Mo carbonitride via the urea reaction and Mo nitride via the AC reaction were determined to be MoC0.5N0.5 and MoN by X-ray diffractometry, respectively. Nevertheless, amorphous states of carbons and their related compounds, unreacted residual MoO3, and incompletely reacted MoO2 remained in the films, as determined by other thin film analyses. When the residual MoO2 was minimal, the films exhibited the lowest electrical resistivity, i.e., ∼10−4 Ω·cm for Mo carbonitride and ∼10−3 Ω·cm for Mo nitride, implying an optimum metallic phase transition. Our results pave the way for the nitriding and carbonitriding of transition metal oxides using ammonium salt precursors for a one-step reaction in the CVD process.

Superconducting thin films are widely applied in various fields, including switching devices, because of their phase transition behaviors in relation to temperature changes. Therefore, it is important to quantitatively determine the optical constant of a superconducting material in the thin-film state. We performed a terahertz time-domain spectroscopy, based on a 10 femtoseconds pulse laser, to measure the optical constant of a superconducting GdBa2Cu3O7−x (GdBCO) thin film in the terahertz region. We then estimated the terahertz refractive indices of the 70 nm-thick GdBCO film using a numerical extraction process, even though the film thickness was approximately 1/10,000 times smaller than the terahertz wavelength range of 200 μm to 1 mm. The resulting refractive indices of the GdBCO thin film were consistent with the theoretical results using the two-fluid model. Our work will help to further understand the terahertz optical properties of superconducting thin films with thicknesses under 100 nm, as well as provide a standard platform for characterizing the optical properties of thin films without the need of Kramers–Kronig transformation at the terahertz frequencies.

To develop a high voltage read margin ΔVrd, deep reset engineering and defect engineering are proposed. To realize the defect engineering, the amount of oxygen vacancy of the resistor was controlled by optimizing the material of the reservoir (RSV) and switching oxide. We investigated the barrier height modulation, which was formed by the Ru bottom electrode (BE) having a high work function, to demonstrate the concept of deep reset engineering by reducing the set current (Iset) of the HfO2 resistor (1R) to the turn-on current (Ith) of the selector device (1S). Further, we identified the causes of the negative set fail through the chemical analysis of the HfO2/BE TiN interface to improve the reset switching fail. Unstable TiON and TiOx chemical species, which present in the interface of HfO2/BE TiN, take oxygen from the resistor HfO2 and create the parasitic defect (or filament), which was injected from BE TiN. To improve the negative set fail of RRAM, we proposed the O3 surface treatment of BE TiN at a high temperature (∼320 °C) and the BE Ru with a superior oxidation resistance. By using deep reset engineering, we successfully increased the ΔVrd of 1S1R by more than 0.5 V. We also demonstrated that Ru BE and the O3 surface treatment of BE TiN improved both the reset window and the negative set.

AlGaN/GaN heterostructures were successfully grown with the AlIn(Ga)N back barrier at 900 °C. However, the atomic composition of the AlIn(Ga)N layer was strongly dependent on the growth pressure, which resulted in a different lattice constant of the layer. The AlIn(Ga)N back barrier grown at 400 torr was almost lattice-matched to GaN layer. The AlGaN/GaN heterostructures with 10 and 15 nm-thick AlIn(Ga)N back barrier exhibited improved 2-DEG properties, compared to those of the conventional AlGaN/GaN heterostructure without the back barrier. The high electron mobility transistors (HEMTs) fabricated on the AlGaN/GaN heterostructure with a 15 nm-thick AlIn(Ga)N back barrier exhibited a very low off-state leakage current of ∼2 × 10−7 A/mm which is about 1 order lower in magnitude than the value of the device without the back barrier. The AlIn(Ga)N back barrier is a promising candidate as an alternative to conventional AlGaN and InGaN back barrier.

We investigate ultrafast dynamics from photoinduced reflectivity of ${\mathrm{Sr}}_{2}{\mathrm{RhO}}_{4}$ by using femtosecond near-infrared pulses. We observe a clear temperature dependent anomaly in its electronic dynamics which slows down below ${T}_{\mathrm{S}}\ensuremath{\sim}160$ K. In addition, coherent oscillations of the 5.3 THz ${A}_{1g}$ phonon exhibit a ${90}^{\ensuremath{\circ}}$ shift in its initial phase across ${T}_{\mathrm{S}}$, indicating a structural change in octahedral rotation distortions. We propose that octahedral structure in ${\mathrm{Sr}}_{2}{\mathrm{RhO}}_{4}$ evolves around ${T}_{\mathrm{S}}$, and it can influence the nonequilibrium dynamics of photo-induced carriers as well as realtime phonon responses.

We report optical spectra of underdoped BaFe1.89Co0.11As2 that hosts both of magnetic and superconducting orders. The temperature dependent evolution of optical conductivity shows finger prints of the magnetic order and the s-wave nature of the superconducting gaps. Careful inspection on the superconducting state reveals that the two orders compete but coexist in the ground state.

With the technique of infrared ellipsometry we performed a detailed study of the temperature- and doping dependence of the c-axis response of a series of YBa₂Cu₃O7−δ single crystals. In particular, we explored the anomalous electronic properties at temperatures above the macroscopic superconducting transition temperature, T c, whose conflicting explanations range from a precursor superconducting state to electronic correlations that compete with superconductivity. We show that the c-axis spectra provide evidence that both kinds of correlations are present and that their contributions can be disentangled based on an analysis with a so-called multilayer-model. We find that the onset temperature, T *, and the energy scale, ΔPG, of the competing pseudogap increase rapidly towards the underdoped side whereas they vanish on the overdoped side. In addition, we provide evidence that in a strongly underdoped sample the precursor superconducting correlations develop below an onset temperature, T ons, that is considerably lower than T * but still much higher than T c.

In this paper, the authors report for the first time the outstanding selector performance from an innovative oxide selector. SiO2, one of conventional and common materials in semiconductor industry, was chosen as a matrix oxide material. Metal atoms which are non-mobile and easy to handle were injected into the oxide films. Off-current and threshold voltage (V th ) could be controlled by using arsenic (As), which doping method and concentration were carefully investigated to achieve threshold switching behavior. Finally ReRAM (Resistance switching Random Access Memory) cell array consisted of one selector-one resistor (1S1R) was successfully demonstrated with the full integration of the newly developed selector.

We investigated the electronic structure of $[{(\mathrm{SrIr}{\mathrm{O}}_{3})}_{m},(\mathrm{SrTi}{\mathrm{O}}_{3})](m=\phantom{\rule{0.16em}{0ex}}1,\phantom{\rule{0.16em}{0ex}}2,\mathrm{and}\phantom{\rule{0.16em}{0ex}}\ensuremath{\infty})$ superlattice (SL) thin films with optical spectroscopy and first principles calculations. Our optical results confirmed the existence of the ${J}_{\mathrm{eff}}=1/2$ states in SL samples, similar to the bulk Ruddlesden-Popper series $\mathrm{S}{{\mathrm{r}}_{n}}_{+1}\mathrm{I}{\mathrm{r}}_{n}{\mathrm{O}}_{3n+1}$ iridates. Apart from this similarity, in the SL samples, we observed red shifts of the characteristic optical excitations in the ${J}_{\mathrm{eff}}=1/2$ state and an enhancement of the low-energy spectral weight, which implies a reduction in the effective electron correlation for bands near the Fermi energy. The density functional theory plus Coulomb interactions $(\mathrm{DFT}+U)$ calculations suggested that the $\mathrm{SrTi}{\mathrm{O}}_{3}$ layer intervened between $\mathrm{SrIr}{\mathrm{O}}_{3}$ layers in the SLs activated additional hopping channels between the Ir ions, thus increasing the bandwidth and reducing the effective strength of the correlations. This paper demonstrates that fabrication of iridium-based heterostructures can be used to finely tune electronic structures via alteration of their local orbital environments.

We report a temperature-dependent optical spectroscopic study of the Heisenberg-Kitaev magnet $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{RuCl}}_{3}$. Our measurements reveal anomalies in the optical response near the magnetic ordering temperature. At higher temperatures, we observe a redistribution of spectral weight over a broad energy range that is associated with nearest-neighbor spin-spin correlations. This finding is consistent with highly frustrated magnetic interactions and in agreement with theoretical expectations for this class of material. The optical data also reveal significant electron-hole interaction effects, including a bound excitonic state. These results demonstrate a clear coupling between charge and spin degrees of freedom and provide insight into the properties of thermally disordered Heisenberg-Kitaev magnets.

Agricultural irrigation system is required to be designed economically and should be reliable with minimal suspension in watersupply. This study suggests a multi-criteria design approach for irrigation pipe network systems. A system reliability is suggestedas a second objective, which is defined as annual non-supplied volume of water by considering pipe failure. The non-suppliedwater is quantified based on the expected number of pipe failure and pipe repair time. A hydraulic simulator(EPANET) is linkedwith a heuristic-search optimization algorithm(Genetic Algorithm, GA) for least-cost system design. Once the least-cost design isdetermined, the system reliability is calculated for the obtained optimal design. In order to evaluate the relation between systemcost and water-supply reliability, three layouts(two branch- and a looped-networks) were suggested for least-cost design and reli-ability estimation. The application results showed that the multi-criteria design approach is superior than single-objective designscheme by providing decision makers with additional information to determine optimal designs.Key words : Agricultural irrigation system; Water distribution system; Optimization; System reliability

A deeper look into iron selenide In the past 10 years, iron-based superconductors have created more puzzles than they have helped resolve. Some of the most fundamental outstanding questions are how strong the interactions are and what the electron pairing mechanism is. Now two groups have made contributions toward resolving these questions in the intriguing compound iron selenide (FeSe) (see the Perspective by Lee). Gerber et al. used photoemission spectroscopy coupled with x-ray diffraction to find that FeSe has a very sizable electron-phonon interaction. Quasiparticle interference imaging helped Sprau et al. determine the shape of the superconducting gap and find that the electron pairing in FeSe is orbital-selective. Science , this issue p. 71 , p. 75 ; see also p. 32

We report an optical spectroscopic study of $\mathrm{SrMnS}{\mathrm{b}}_{2}$, a low-carrier-density metal. As temperature is decreased, our measurements reveal a large increase in the quasiparticle plasma frequency, which is highly unusual for a metal. This seemingly anomalous behavior can be accounted for using a ``three-band'' model of the multiband electronic structure of $\mathrm{SrMnS}{\mathrm{b}}_{2}$ that includes two conduction bands and one valence band. The second conduction band is assumed to be heavy and its minimum is taken to be close to, but not intersecting, the Fermi level. At finite temperature, quasiparticles are thermally redistributed between the two conduction bands, leading to an increase in the optical effective mass and a decrease in the plasma frequency. The temperature dependence of the low-lying interband optical transitions and the Hall number can also be understood using our model. The phenomenology of such a three-band scenario has not been widely considered to date in optical spectroscopic studies. Our results provide an explanation for the puzzling optical properties that have previously been reported in a number of topical low-carrier-density metals and semimetals and lay a foundation for future optical studies of these materials.

Tunneling Field Effect Transistors (TFETs) are considered as a candidate for low power applications. However, most of TFETs have been researched on only for long channels due to the misalignment problem that occurs during the source/drain doping process in device fabrication. Thus, a new method is proposed for the fabrication of TFETs in nanoscale regions. This proposed fabrication process does not need an additional mask to define the source/drain regions, and makes it possible to form a self-aligned source/drain doping process. In addition, through TCAD simulation, the electrical characteristics of a TFET with dopant engineering and a rounded gate edge shape for a higher on/off current ratio were investigated. As a result, the TFET showed the properties of a larger on-current, a lower average subthreshold swing (58.5 mV/dec), and a 30-fold smaller leakage current compared to the conventional TFET The TFET with dopant engineering and a rounded gate edge shape can also be fabricated simply through the proposed fabrication process.

We investigated the metal-insulator transition (MIT) driven by all-in-all-out (AIAO) antiferromagnetic ordering in the 5d pyrochlore Cd(2)Os(2)O(7) using optical spectroscopy and first-principles calculations. We showed that the temperature evolution in the band-gap edge and free carrier density were consistent with rigid upward (downward) shifts of electron (hole) bands, similar to the case of Lifshitz transitions. The delicate relationship between the band gap and free carrier density provides experimental evidence for the presence of an AIAO metallic phase, a natural consequence of such MITs. The associated spectral weight change at high energy and first-principles calculations further support the origin of the MIT from the band shift near the Fermi level. Our data consistently support that the MIT induced by AIAO ordering in Cd(2)Os(2)O(7) is not close to a Slater type but instead to a Lifshitz type.

In this paper, the authors report that 2x nm cross-point ReRAM with 1S1R structure has been successfully developed. Off-current at 1/2 Vsw of 1S1R is one of key factor for high-density ReRAM. NbO2 was chosen as a selector material and off-current and forming characteristics were improved by using stack engineering of top and bottom barriers as well as spacer materials. Finally array operation was characterized with the integration of selector and resistor materials.

A single-electron transistor (SET) is one of the promising solutions to overcome the scaling limit of the Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET). Up to now, various kinds of SETs are being proposed and SETs with a dual gate (DG) structure using an electrical potential barrier have been demonstrated for room temperature operation. To operate DG-SETs, however, extra bias of side gates is necessary. It causes new problems that the electrode for side gates and the extra bias for electrical barrier increase the complexity in circuit design and operation power consumption, respectively. For the reason, a new mechanism using work function (WF) difference is applied to operate a SET at room temperature by three electrodes. Its structure consists of an undoped active region, a control gate, n-doped source/drain electrodes, and metal/silicide or p-type silicon side gates, and a SET with metal/silicide gates or p-type silicon gates forms tunnel barriers induced by work function between an undoped channel and grounded side gates. Via simulation, the effectiveness of the new mechanism is confirmed through various silicide materials that have different WF values. Furthermore, by considering the realistic conditions of the fabrication process, SET with p-type sidewall spacer gates was designed, and its brief fabrication process was introduced. The characteristics of its electrical barrier and the controllability of its control gate were also confirmed via simulation. Finally, a single-hole transistor with n-type sidewall spacer gates was designed.

We present broad-band infrared ellipsometry measurements of the c -axis dielectric response of underdoped YBa 2 Cu 3 O 7− d single crystals. Our data provide a clear spectroscopic distinction between the normal-state pseudogap and the superconducting gap. In particular, they establish that different energy scales are underlying the respective redistributions of spectral weight. Furthermore, our data are suggestive of a mutual competition between the two gaps and thus of an extrinsic nature of the pseudogap with respect to superconductivity.

Electronic devices that use the spin degree of freedom hold unique prospects for future technology. The performance of these 'spintronic' devices relies heavily on the efficient transfer of spin polarization across different layers and interfaces. This complex transfer process depends on individual material properties and also, most importantly, on the structural and electronic properties of the interfaces between the different materials and defects that are common to real devices. Knowledge of these factors is especially important for the relatively new field of organic spintronics, where there is a severe lack of suitable experimental techniques that can yield depth-resolved information about the spin polarization of charge carriers within buried layers of real devices. Here, we present a new depth-resolved technique for measuring the spin polarization of current-injected electrons in an organic spin valve and find the temperature dependence of the measured spin diffusion length is correlated with the device magnetoresistance.

Background/Objectives: Korea is currently using F/S and CR systems for diagnostic radiation equipment. However, due to the lack of quality assurance items, further research regarding the criteria and items of diagnostic radiation equipment for analog and digital systems is needed. Methods/Statistical analysis: Diagnostic radiation equipment installed at H University in Chungnam, Korea, was used for testing and both F/S and CR systems were scrutinized. For the F/S system, a 10×12inch cassette, 10×12inch films and an automatic developing machine (JP-33) were used. The CR system was assessed using a 10x12 inch IP cassette and an image reader. The measurement items comprised the uniformity of images, resolution, and high-contrast resolution. Findings: In the uniformity test, the difference in optical density between the F/S system and the CR system was ±0.1%. Regarding uniformity, the IEC recommends an optical density baseline difference to be less than ±0.10. The uniformity of this test meets international standards. In the high-contrast resolution test, F/S system and CR system values were 4.0 and 3.0, respectively. In the resolution test, F/S system and CR system values were 5.62 and 4.61 at 5mAs, respectively. At 10mAs, the F/S system’s value was 5.62 and that of the CR system was 4.84. Improvements/Applications: The uniformity test, high-contrast resolution test, and resolution test results showed the F/S system to be superior to the CR system. Therefore, it is considered that the uniformity test, the high-contrast resolution test, and the resolution test should be performed as common items in the quality assurance of each system’s diagnostic radiation equipment.

Two concepts of ultrafast spin control at THz frequencies are presented: Exploiting a coherent phonon mode we transiently induce and destroy spin order in pnictides at a frequency as high as 5.5 THz. Strong THz magnetic fields control magnons in antiferromagnetic NiO coherently by direct Zeeman coupling.

Manipulating the orbital state in a strongly correlated electron system is of fundamental and technological importance for exploring and developing novel electronic phases. Here, we report an unambiguous demonstration of orbital occupancy control between t(2g) and e(g) multiplets in quasi-two-dimensional transition metal oxide superlattices (SLs) composed of a Mott insulator LaCoO3 and a band insulator LaAlO3. As the LaCoO3 sublayer thickness approaches its fundamental limit (i.e. one unit-cell-thick), the electronic state of the SLs changed from a Mott insulator, in which both t(2g) and e(g) orbitals are partially filled, to a band insulator by completely filling (emptying) the t(2g) (e(g)) orbitals. We found the reduction of dimensionality has a profound effect on the electronic structure evolution, which is, whereas, insensitive to the epitaxial strain. The remarkable orbital controllability shown here offers a promising pathway for novel applications such as catalysis and photovoltaics, where the energy of d level is an essential parameter.

Authors present optical spectroscopy measurements of 5d transition metal oxide Sr${}_{2}$IrO${}_{4}$. The results are interpreted in terms of orbital-dependent electron-phonon interaction and are essential for understanding the physics of this material.

We measured temperature-dependent reflectivity spectra of non-perovskite nine layer BaRuO3 single crystal and four layer BaRuO3 epitaxial film. In optical conductivity spectra obtained through Kramers–Kronig transformation, we observed that both materials show pseudogap formations in their metallic states. A clear development of pseudogap as well as a coherent component as a function of temperature is evidently distinguished from other pseudogap systems, such as high Tc cuprates and heavy electron systems. We suggested that these interesting features should be related to the structural characteristics of the layered structures with face-sharing of RuO6 octahedra, which might induce one-dimensional (1D) instability.

Optical spectra of nine-layer BaRuO3 show clear electrodynamic response changes due to a pseudogap formation. As temperature decreases, the pseudogap formation induces a gradual reduction of carrier density n and an abrupt suppression of scattering rate 1/τ. It was found that the competition between n and 1/τ can induce a crossover from metallic to insulator-like regions. A clear development of the pseudogap as well as the coherent component in BaRuO3 is evidently distinguished from other pseudogap phenomena observed in high Tc cuprates and heavy-electron systems.

We studied the doping and temperature (T) dependence of the infrared (IR) response of Ba(Fe1_xCox)2As2 single crystals. We show that a weak band around 1000 cm_1, that was previously interpreted in terms of interaction of the charge carriers with magnetic excitations or of a pseudogap, is rather related to low energy interband transitions. Specifically, we show that this band exhibits a similar doping and T dependence as the hole pockets seen by angle resolved photoemission spectroscopy (ARPES). Notably, we find that it vanishes as a function of doping near the critical point where superconductivity is suppressed in the overdoped regime. Our IR data thus provide bulk specific information (complementary to the surface sensitive ARPES) for a Lifshitz transition. Our IR data also reveal a second low-energy band around 2300 cm_1 which further emphasizes the necessity to consider the multiband nature of these iron arsenides in the analysis of the optical response.

Diphenylmethyl (DPM) and p-methoxybenzyl (PMB) ester of cephalosporin derivatives were converted to the corresponding carboxylic acid using iodotrimethylsilane (TMSI)-triphenylphosphine (TPP) in dichloromethane at room temperature in good yields.

With ellipsometry, x-ray diffraction, and resistance measurements we investigated the electric-field effect on the confined electrons at the LaAlO3=SrTiO3 interface. We obtained evidence that the localization of the electrons at negative gate voltage is induced, or at least enhanced, by a polar phase transition in SrTiO3 which strongly reduces the lattice polarizability and the subsequent screening. In particular, we show that the charge localization and the polar order of SrTiO3 both develop below similar to 50 K and exhibit similar, unipolar hysteresis loops as a function of the gate voltage.

Ultrashort pulses in the terahertz (THz) spectral range allow us to study and control spin dynamics on time scales faster than a single oscillation cycle of light. In a first set of experiments, we harness an optically triggered coherent lattice vibration to induce a transient spin-density wave in BaFe2As2, the parent compound of pnictide superconductors. The time-dependent multi-THz response of the non-equilibrium phases shows that the ordering quasi-adiabatically follows a coherent lattice oscillation at a frequency as high as 5.5 THz. The results suggest important implications for unconventional superconductivity. In a second step, we utilize the magnetic field component of intense THz transients to directly switch on and off coherent spin waves in the antiferromagnetic nickel oxide NiO. A femtosecond optical probe traces the magnetic dynamics in the time domain and verifies that the THz field addresses spins selectively via Zeeman interaction. This concept provides a universal ultrafast handle on magnetic excitations in the electronic ground state.

We have measured the temperature dependence of the direct band gap, $E_g$, in SrTi$^{16}$O$_3$ and BaTiO$_3$ and related materials with quantum-paraelectric and ferroelectric properties using optical spectroscopy. We show that $E_g$ exhibits an anomalous temperature dependence with pronounced changes in the vicinity of the ferroelectric transition that can be accounted for in terms of the Fr\"ohlich electron-phonon interaction with an optical phonon mode, the so-called soft mode. We demonstrate that these characteristic changes of $E_g$ can be readily detected even in very thin films of SrTi$^{16}$O$_3$ with a strain-induced ferroelectric order. Optical spectroscopy thus can be used as a relatively simple but sensitive probe of ferroelectric order in very thin films of these titanates and probably also in subsequent multilayers and devices., Comment: 6 pages, 3 figures, and supplementary material; accepted for publication in Phys. Rev. B

Supply voltage (V DD ) scaling has been an important issue as the CMOS scaling down. Scaling of devices induces large leakage current due to Short Channel Effects (SCEs). Also, Subthrehold Swing (SS) value of CMOS devices is theoretically limited to 60 mV/dec. Various structures have been proposed to overcome power dissipation problems, one of which is the TFETs [1–2]. However, TFET has two critical drawbacks such as low on-current level and ambipolar behaviors. To overcome these disadvantages, TFET using hetero-gate dielectric materials has been lately reported [3]. Although this TFET has low SS and high on-current level, it is difficult to control dielectric alignment between high-k material and SiO 2 in the process. Thus, we introduce an improved TFET in terms of fabrication and performance.

Modern VLSI technology has been developed with continuous scaling of MOSFET. However, as MOSFET has been scaled down, a lot of critical issues have risen and resulted in a considerable degradation of individual devices [1]. On the other hand, owing to its periodic on/off characteristic, single-electron transistor (SET) attracts attention with its promising performance. But, in general, fabricating SET, silicon-on-insulator (SOI) wafers have been used for their leakage current through buried oxide (BOX) on the substrate region [2]. However, in this paper, we propose a vertical structure that is fabricated on a bare wafer, not on a SOI wafer, and the fabrication process with which small size of a quantum dot (QD) can be formed more easily than previous works [1][3]. Since the smaller QD a SET has, the better operation characteristic it has at room temperature (RT), the characteristic of the SET device can be observed more clearly than previous works with the simple process to downsize a QD.

The interplay among charge, spin and lattice degrees of freedom in solids gives rise to intriguing macroscopic quantum phenomena such as colossal magnetoresistance, multiferroicity and high-temperature superconductivity. Strong coupling or competition between various orders in these systems presents the key to manipulate their functional properties by means of external perturbations such as electric and magnetic fields or pressure. Ultrashort and intense optical pulses have emerged as an interesting tool to investigate elementary dynamics and control material properties by melting an existing order. Here, we employ few-cycle multi-terahertz pulses to resonantly probe the evolution of the spin-density-wave (SDW) gap of the pnictide compound BaFe(2)As(2) following excitation with a femtosecond optical pulse. When starting in the low-temperature ground state, optical excitation results in a melting of the SDW order, followed by ultrafast recovery. In contrast, the SDW gap is induced when we excite the normal state above the transition temperature. Very surprisingly, the transient ordering quasi-adiabatically follows a coherent lattice oscillation at a frequency as high as 5.5 THz. Our results attest to a pronounced spin-phonon coupling in pnictides that supports rapid development of a macroscopic order on small vibrational displacement even without breaking the symmetry of the crystal.

We show that a miltilayer analysis of the infrared c-axis response of RBa2Cu3O7-delta (R=Y,Gd,Eu) provides important new information about the anomalous normal-state properties of underdoped curprate high temperature superconductors. In addition to competing correlations which give rise to a pseudogap that depletes the low-energy electronic states below T*>>Tc, it enables us to identify the onset of a precursor superconducting state below Tons>Tc. We map out the doping phase diagram of Tons which reaches a maximum of 180K at strong underdoping and present magnetic field dependent data which confirm our conclusions.

We measure the anisotropic midinfrared response of electrons and phonons in bulk YBa(2)Cu(3)O(7-δ) after femtosecond photoexcitation. A line shape analysis of specific lattice modes reveals their transient occupation and coupling to the superconducting condensate. The apex oxygen vibration is strongly excited within 150 fs, demonstrating that the lattice absorbs a major portion of the pump energy before the quasiparticles are thermalized. Our results attest to substantial electron-phonon scattering and introduce a powerful concept probing electron-lattice interactions in a variety of complex materials.

We report muon spin rotation (mu SR) and infrared spectroscopy experiments on underdoped BaFe1.89Co0.11As2 which show that bulk magnetism and superconductivity (SC) coexist and compete on the nanometer length scale. Our combined data reveal a bulk magnetic order, likely due to an incommensurate spin density wave (SDW), which develops below T-mag approximate to 32 K and becomes reduced in magnitude (but not in volume) below T-c = 21.7 K. A slowly fluctuating precursor of the SDW seems to develop already below the structural transition at T-s approximate to 50 K. The bulk nature of SC is established by the mu SR data which show a bulk SC vortex lattice and the IR data which reveal that the majority of low-energy states is gapped and participates in the condensate at T << T-c.

We performed combined infrared reflection and ellipsometry measurements of the in-plane optical response of single crystals of the pnictide high-temperature superconductor ${\text{BaFe}}_{1.87}{\text{Co}}_{0.13}{\text{As}}_{2}$ with ${T}_{c}=24.5\text{ }\text{K}$. Our experimental data provide evidence for multiple superconducting energy gaps and can be well described in terms of three isotropic gaps with $2\ensuremath{\Delta}/{k}_{B}{T}_{c}$ of 3.1, 4.7, and 9.2. The obtained low-temperature value of the in-plane magnetic penetration depth is 270 nm.

With infrared ellipsometry and transport measurements we investigated the electrons at the interface between ${\mathrm{LaAlO}}_{3}$ and ${\mathrm{SrTiO}}_{3}$. We obtained a sheet carrier concentration of ${N}_{\mathrm{s}}\ensuremath{\approx}5--9\ifmmode\times\else\texttimes\fi{}{10}^{13}\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}2}$, an effective mass of ${m}^{*}=3.2\ifmmode\pm\else\textpm\fi{}0.4{m}_{e}$, and a strongly frequency dependent mobility. The latter are similar as in bulk ${\mathrm{SrTi}}_{1\ensuremath{-}x}{\mathrm{Nb}}_{x}{\mathrm{O}}_{3}$ and therefore suggestive of polaronic correlations. We also determined the vertical concentration profile which has a strongly asymmetric shape with a rapid initial decay over the first 2 nm and a pronounced tail that extends to about 11 nm.

We probe the mid-infrared conductivity of YBa 2 Cu 3 O 7-δ parallel and perpendicular to the CuO 2 planes after 12-fs optical excitation. Quasiparticle excitations and specific lattice modes are traced simultaneously during the photoinduced non-thermal transition to the normal state. The condensate is completely destroyed within 150 fs, while characteristic phonon resonances undergo a blue-shift on distinctly slower times of up to 0.9 ps. The results indicate selective electronphonon coupling and strong lattice anharmonicities.

We probe the mid-infrared dielectric response of optimally doped YBa2Cu3O7-δafter 12-fs optical excitation to simultaneously trace quasiparticles and specific lattice modes. Our results identify an extremely non-thermal regime and highly selective electron-phonon coupling.

We present the first spectrally-resolved study of the femtosecond dynamics in La2CuO4, the undoped parent-compound of the high-temperature superconductor. The data reveal strong band-gap renormalization and the appearance of in-gap states attributed to photo-doping.

We investigated the electronic structures of the 5d Ruddlesden-Popper series Sr n+1Ir nO3n+1 (n=1, 2, and infinity) using optical spectroscopy and first-principles calculations. As 5d orbitals are spatially more extended than 3d or 4d orbitals, it has been widely accepted that correlation effects are minimal in 5d compounds. However, we observed a Mott insulator-metal transition with a change of bandwidth as we increased n. In addition, the artificially synthesized perovskite SrIrO3 showed a very large mass enhancement of about 6, indicating that it was in a correlated metallic state.