Terahertz BWO-Spectrosopy

Gorshunov, B.; Волков, А. А.; Spektor, I. E.; Prokhorov, A. S.; Mukhin, A. A.; Dressel, Martin; Uchida, Satoshi; Loidl, A.

doi:10.1007/s10762-005-7600-y

Cited by 169 publications

(81 citation statements)

References 16 publications

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“…For T < 100 K the optical transmission was measured in the THz range (18 − 46 cm −1 ) using a coherent source spectrometer. 27 In all cases, the light was polarized in the two main directions of the crystal planes, indicated also in Fig. 1(b).…”

Section: Methodsmentioning

confidence: 67%

Power-law dependence of the optical conductivity observed in the quantum spin-liquid compoundκ-(BEDT-TTF)2Cu2(CN)
Elsässer
¹
,
Wu
²
,
Dressel
³

et al. 2012
Phys. Rev. B

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Section: Methodsmentioning

confidence: 67%

Power-law dependence of the optical conductivity observed in the quantum spin-liquid compoundκ-(BEDT-TTF)2Cu2(CN)
Elsässer
¹
,
Wu
²
,
Dressel
³

et al. 2012
Phys. Rev. B

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“…34 A Mach-Zehnder interferometer arrangement of the spectrometer allows to measure both the intensity and the phase shift of the wave transmitted through the Ba(Fe 0.9 Co 0.1 ) 2 As 2 film and the substrate 35 . Using the Fresnel optical formulas for the complex transmission coefficient of the two-layer system, both components of the complex conductivity (σ 1 + iσ 2 ) of the film have been calculated.…”

Section: Methodsmentioning

confidence: 99%

Highly anisotropic energy gap in superconductingBa(Fe0.9Co0.1)2

et al. 2010

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We have measured the complex dynamical conductivity, σ = σ1 + iσ2, of superconducting Ba(Fe0.9Co0.1)2As2 (Tc = 22 K) at terahertz frequencies and temperatures 2 -30 K. In the frequency dependence of σ1 below Tc, we observe clear signatures of the superconducting energy gap opening. The temperature dependence of σ1 demonstrates a pronounced coherence peak at frequencies below 15 cm −1 (1.8 meV). The temperature dependence of the penetration depth, calculated from σ2, shows power-law behavior at the lowest temperatures. Analysis of the conductivity data with a two-gap model, gives the smaller isotropic s-wave gap of ∆A = 3 meV, while the larger gap is highly anisotropic with possible nodes and its rms amplitude is ∆0 = 8 meV. Overall, our results are consistent with a two-band superconductor with an s± gap symmetry.

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“…This means that potential wells associated with quantum dots are shallower in a deeper located layer of the clusters and the main contribution to the useful signal in the capacitance-voltage characteristics most likely comes from the fifth (closest to the surface) layer of Ge clusters. The terahertz and sub-terahertz characteristics of the prepared structures were measured at room temperature with a quasioptical spectrometer using backward wave oscillators (BWO) as monochromatic radiation sources continuously tunable in the frequency [20]. A BWO-spectrometer spectrometer is an efficient instrument for investigating terahertz and sub-terahertz electrodynamic properties of various objects from insulators and semiconductors to systems with correlated electrons [21].…”

Section: Doi: 101134/s0021364010240033mentioning

confidence: 99%

“…To describe absorption, we take two characteristics: dynamic conductivity σ and absorption coefficient α = 4πk/λ, where k is the attenuation coefficient or the imaginary part of the complex refractive index n* = n + ik and λ is the wave length of radiation [23]. These quantities σ and α were determined by the procedure of processing spectra measured by a backward wave tube spectrometer [20] using the Fresnel expressions for the transmission coefficient of layered systems [22]. In our case, the system contains 13 layers: the substrate, buffer and cap layers, and five double layers consisting of Ge quantum dots and an Si barrier layer.…”

Section: Doi: 101134/s0021364010240033mentioning

confidence: 99%

Absorption of terahertz radiation in Ge/Si(001) heterostructures with quantum dots

et al. 2010

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The terahertz spectra of the dynamic conductivity and radiation absorption coefficient in germanium-silicon heterostructures with arrays of Ge hut clusters (quantum dots) have been measured for the first time in the frequency range of 0.3-1.2 THz at room temperature. It has been found that the effective dynamic conductivity and effective radiation absorption coefficient in the heterostructure due to the presence of germanium quantum dots in it are much larger than the respective quantities of both the bulk Ge single crystal and Ge/Si(001) without arrays of quantum dots. The possible microscopic mechanisms of the detected increase in the absorption in arrays of quantum dots have been discussed. DOI: 10.1134/S0021364010240033Artificial low-dimensional nanoobjects-quantum wells, quantum wires, and quantum dots-as well as structures based on them, are promising systems for improvement of existing devices and development of fundamentally new devices of micro and optoelectronics [1]. In addition to the necessity of the development of new technological processes and equipment for manufacturing nanostructures with required parameters, the investigation of the fundamental properties of such structures is also of primary importance. Size quantization of the energy of charge carriers whose spatial motion is limited at scales of about 100 nm or smaller is one of the most striking such properties. In particular, a quantum dot is a zero dimensional object can be considered as an artificial atom with one or more charge carriers (electrons or holes) having a discrete energy spectrum [2]. Arrays of a large number of quantum dots including multilayer heterostructures make it possible to form artificial "solids" whose properties can be controllably changed by varying the characteristics of constituent elements ("atoms") and the environment (semiconductor matrix). Such systems can have a very rich set of physical properties, which are caused by single-particle and collective interactions and depend on the number and mobility of carriers in quantum dots, Coulomb interaction between the carriers inside a quantum dot and in neighboring quantum dots, charge coupling between neighboring quantum dots, polaron and exciton effects, etc. These properties are actively studied during the last two decades. One of the main tools for such investigations is infrared spectroscopy, whose advantages are the contactless character of the measurements and the possibility of the direct observation of transitions between quantized energy states. The specificity of the infrared region is that almost all main interactions in low-dimensional nanostructures (distance between levels, Coulomb interaction between charges in quantum dots, one and multi-particle exciton and polaron effects, plasmon excitations) have the corresponding characteristic energies from several meV to 50-100 meV [3][4][5][6][7].It is worth noting that almost all performed infrared spectroscopy experiments were devoted to the measurement of the relative characteristics (e.g., relative tra...

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Terahertz BWO-Spectrosopy

Cited by 169 publications

References 16 publications

Power-law dependence of the optical conductivity observed in the quantum spin-liquid compoundκ-(BEDT-TTF)2Cu2(CN)
Elsässer
¹
,
Wu
²
,
Dressel
³

et al. 2012
Phys. Rev. B

Power-law dependence of the optical conductivity observed in the quantum spin-liquid compoundκ-(BEDT-TTF)2Cu2(CN)
Elsässer
¹
,
Wu
²
,
Dressel
³

et al. 2012
Phys. Rev. B

Highly anisotropic energy gap in superconductingBa(Fe0.9Co0.1)2

Absorption of terahertz radiation in Ge/Si(001) heterostructures with quantum dots

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Terahertz BWO-Spectrosopy

Cited by 169 publications

References 16 publications

Power-law dependence of the optical conductivity observed in the quantum spin-liquid compoundκ-(BEDT-TTF)2Cu2(CN)Elsässer1, Wu2, Dressel3 et al. 2012Phys. Rev. B

Power-law dependence of the optical conductivity observed in the quantum spin-liquid compoundκ-(BEDT-TTF)2Cu2(CN)Elsässer1, Wu2, Dressel3 et al. 2012Phys. Rev. B

Highly anisotropic energy gap in superconductingBa(Fe0.9Co0.1)2

Absorption of terahertz radiation in Ge/Si(001) heterostructures with quantum dots

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Product

Resources

About

Power-law dependence of the optical conductivity observed in the quantum spin-liquid compoundκ-(BEDT-TTF)2Cu2(CN)
Elsässer
¹
,
Wu
²
,
Dressel
³

et al. 2012
Phys. Rev. B

Power-law dependence of the optical conductivity observed in the quantum spin-liquid compoundκ-(BEDT-TTF)2Cu2(CN)
Elsässer
¹
,
Wu
²
,
Dressel
³

et al. 2012
Phys. Rev. B