Effect of annealing on the temperature-dependent dielectric properties of LaAlO3 at terahertz frequencies

Zou, Xingquan; He, Miao; Springer, Daniel; Lee, Dong‐Wook; Nair, Saritha K.; Cheong, Siew Ann; Wu, Tom; Panagopoulos, C.; Talbayev, Diyar; Chia, Elbert E. M.

doi:10.1063/1.3679725

Cited by 7 publications

(8 citation statements)

References 22 publications

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“…1(g)] and an absorption coefficient similar to that reported in Ref. [13]. However, rather than representing real physical absorption the anisotropy of the refractive index has resulted in a polarization rotation.…”

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confidence: 67%

“…Raman scattering and Fourier-transform spectroscopy have unveiled the influence of the rhombohedral distortion on the vibrational modes of LaAlO 3 [4,10,11]. Terahertz (THz) time-domain spectroscopy (TDS) was used previously to examine the complex refractive indexñ n iκ in [001]-oriented LaAlO 3 [12,13] below the lowest frequency optical phonons. Grischkowsky and Keiding reported a refractive index n that increased monotonically from 4.9 at 0.1 THz to 5.1 at 2.0 THz, characteristic of dispersion below an optical phonon frequency, and detected no noticable birefringence [12].…”

mentioning

confidence: 99%

“…Grischkowsky and Keiding reported a refractive index n that increased monotonically from 4.9 at 0.1 THz to 5.1 at 2.0 THz, characteristic of dispersion below an optical phonon frequency, and detected no noticable birefringence [12]. Zou et al reported that thermal annealing at 1273 K modified the complex THz refractive index in the range below 3 THz by creating features similar to three resonant absorption lines [13], and did not discuss any birefringence. However, uniaxial anisotropy of the refractive index (and therefore birefringence) is expected for LaAlO 3 at room temperature, owing to its rhombohedral unit cell [14].…”

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confidence: 99%

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Modifying the polarization state of terahertz radiation using anisotropic twin-domains in LaAlO_3

et al. 2014

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Polarization-resolved terahertz (THz) time-domain spectroscopy was utilized to examine the complex refractive index of lanthanum aluminate (LaAlO3), a rhombohedrally distorted perovskite that exhibits crystallographic twin domains. The uniaxial anisotropy of the refractive index was quantified. The ellipticity of THz radiation pulses after transmission through single domains indicated that LaAlO3 can be used as a quarter- or half-wave plate. The effective anisotropy of [001]-oriented LaAlO3 was found to be reduced when the material exhibited multiple, narrow twin domains.

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confidence: 99%

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confidence: 99%

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Modifying the polarization state of terahertz radiation using anisotropic twin-domains in LaAlO_3

et al. 2014

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“…Moreover, ε ∞ does not just depend on the maximum investigated frequency, as the definition indicates, but also depends on the temperature. Dielectric property studies show that the absorption modes will stiffen or soften with increasing temperature [30]; such stiffening or softening effects directly affect the frequency of the absorption modes and hence the value of ε ∞ . Hence, in our analysis, at every temperature, ε ∞ is one of the fitting parameters in the fit of σ 1 (ω) and σ 2 (ω).…”

Section: Conductivity Theoretical Fitting and Discussionmentioning

confidence: 99%

Temperature-dependent terahertz conductivity of tin oxide nanowire films

Zou¹,

Luo²,

Lee³

et al. 2012

J. Phys. D: Appl. Phys.

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Temperature-dependent terahertz conductivity of tin oxide (SnO 2) nanowire films was measured from 10 to 300 K using terahertz time-domain spectroscopy. The optical parameters, including the complex refractive index, optical conductivity and dielectric function, were obtained using a simple effective medium theory. The complex conductivity was fitted with the Drude-Smith model and the plasmon model. The results show that the carrier density (N) and plasmon resonance frequency (ω 0) increase while the scattering time decreases with increasing temperature. The reduced carrier mobility compared with bulk SnO 2 indicates the presence of carrier localization or trapping in these nanowires.

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“…The temperature dependence of n was also investigated in the Terahertz regime by Zou et al 31 They found that dn/dT is small (not specified) and related to oxygen vacancies and lattice vibrations. In contrast, dn/dT in the visible range reported in this work is related to electronic excitations, see Eq.…”

Section: Temperature-dependent Measurements (80-700 K)mentioning

confidence: 99%

Dielectric function of LaAlO3 from 0.8 to 6 eV between 77 and 700 K

Nelson¹,

Spies²,

Abdallah³

et al. 2012

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Articles you may be interested inImproved dielectric functions in metallic films obtained via template stripping Appl. Phys. Lett. 100, 081105 (2012); 10.1063/1.3687910 Dielectric function spectra and critical-point energies of Cu2ZnSnSe4 from 0.5 to 9.0 eV J. Appl. Phys. 111, 033506 (2012); 10.1063/1.3681814 Dielectric function and electric properties of germanium thin films prepared by gold mediated crystallizationThe authors used spectroscopic ellipsometry to determine the dielectric function and the refractive index of LaAlO 3 as a function of photon energy from 0.8 to 6 eV between 77 and 700 K. The ellipsometric angles were acquired over a broad range of incidence angles with a computercontrolled Berek waveplate compensator and with zone-averaging of the adjustable polarizer. The data were corrected for surface effects, such as surface roughness or adsorbed overlayers. The authors report Tauc-Lorentz model parameters for LaAlO 3 at 300 K. After annealing in UHV for 20 h, the surface layer thickness decreased from 15 Å to less than 1 Å . They speculate that the anneal causes surface modifications, such as the evaporation of adsorbed molecular layers (hydrocarbons or water) or surface vacancies, and that surface diffusion leads to a reduction of surface roughness. They have also measured the temperature-dependence of the refractive index at 1.96 eV between 77 and 700 K and given a theoretical explanation of its origin.

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Effect of annealing on the temperature-dependent dielectric properties of LaAlO3 at terahertz frequencies

Cited by 7 publications

References 22 publications

Modifying the polarization state of terahertz radiation using anisotropic twin-domains in LaAlO_3

Modifying the polarization state of terahertz radiation using anisotropic twin-domains in LaAlO_3

Temperature-dependent terahertz conductivity of tin oxide nanowire films

Dielectric function of LaAlO3 from 0.8 to 6 eV between 77 and 700 K

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