scholarly journals Temperature-dependent optical conductivity of undoped cuprates with weak exchange

2008 ◽  
Vol 78 (6) ◽  
Author(s):  
J. Málek ◽  
S.-L. Drechsler ◽  
U. Nitzsche ◽  
H. Rosner ◽  
H. Eschrig
Keyword(s):  
Optical Conductivity ◽  
Temperature Dependent ◽  
Weak Exchange

scholarly journals Optical Conductivity of Colossal Magnetoresistance Manganites

2021 ◽  
Author(s):  
◽  
Ocean Ripeka Mercier
Keyword(s):  
Energy Range ◽  
Optical Conductivity ◽  
Colossal Magnetoresistance ◽  
Normal Incidence ◽  
Optical Investigation ◽  
Temperature Dependent ◽  
Two Samples ◽  
Before And After ◽  
Interacting Electrons ◽  
Metallic Ferromagnet

<p>The colossal magnetoresistance manganites are a group of materials whose unusual physical properties are a symptom of strongly interacting electrons and phonons. In order to elucidate some of these electronic and vibrational properties, an infrared optical investigation of manganites with a broad range of physical characteristics has been performed. Temperature-dependent normal incidence reflectivity measurements have been made on two samples of manganites, in the energy range of 60 cm-1 - 50000 cm-1, 1 for La0.9 Ca0.1 MnO3, an insulating ferromagnet, and 2 La0.735 Ca0.265 MnO3, a metallic ferromagnet. Temperature-dependent ellipsometric reflection measurements were performed in the energy range of 50 cm-1 - 5000 cm-1, on four faces of two samples of structurally anisotropic manganite, probing the 3. ab plane and c-axis of La1.2 Sr1.8 Mn2O7, a metallic ferromagnet, and 4. the ab plane and c-axis of PrSr2 Mn2O7, an insulating antiferromagnet. The optical conductivity for each of the first two samples has been deduced by a careful Kramers-Kronig analyis of the normal incidence reflectivity. For samples 3. and 4. the optical conductivity has been deduced by inversion of the ellipsometric constants, and a careful subsequent fitting to account for their anisotropy. The transition temperatures and types of magnetic order for all samples have also been characterised by magnetisation measurements. Treatment of the surface is shown to be critical in reflectivity measurements by the observation of hugely contrasting spectra, measured from a polished sample of metallic-like La0.735 Ca0.256 MnO3, before and after annealing. Several features observed in the measurements, especially for the layered materials, are consistent with the idea that a polaron, or electron-lattice interaction, is hugely important in a description of the electron dynamics of these materials. The correlation between spectral features and the structural and magnetic properties of the materials is investigated, finding that the cause of charge transport modification seen in the metallic-like materials could be explained by either a polaron or localisation due to disorder.</p>

scholarly journals Optical Conductivity in the Copper Oxide Materials

1998 ◽  
Vol 12 (18) ◽  
pp. 735-742 ◽  
Author(s):  
Zhongbing Huang ◽  
Shiping Feng
Keyword(s):  
Copper Oxide ◽  
Optical Conductivity ◽  
Low Temperatures ◽  
Oxide Materials ◽  
Conductivity Spectrum ◽  
Temperature Dependent ◽  
Low Energies ◽  
Higher Temperature

The frequency- and temperature-dependent optical conductivity of the copper oxide materials in the underdoped and optimal doped regimes are studied within the t–J model. The conductivity spectrum shows the unsual behavior at low energies and anomalous midinfrared peak in the low temperatures. However, this midinfrared peak is severely depressed with increasing temperatures, and vanishes at higher temperature.

scholarly journals Optical Conductivity of Colossal Magnetoresistance Manganites

2021 ◽  
Author(s):  
◽  
Ocean Ripeka Mercier
Keyword(s):  
Energy Range ◽  
Optical Conductivity ◽  
Colossal Magnetoresistance ◽  
Normal Incidence ◽  
Optical Investigation ◽  
Temperature Dependent ◽  
Two Samples ◽  
Before And After ◽  
Interacting Electrons ◽  
Metallic Ferromagnet

<p>The colossal magnetoresistance manganites are a group of materials whose unusual physical properties are a symptom of strongly interacting electrons and phonons. In order to elucidate some of these electronic and vibrational properties, an infrared optical investigation of manganites with a broad range of physical characteristics has been performed. Temperature-dependent normal incidence reflectivity measurements have been made on two samples of manganites, in the energy range of 60 cm-1 - 50000 cm-1, 1 for La0.9 Ca0.1 MnO3, an insulating ferromagnet, and 2 La0.735 Ca0.265 MnO3, a metallic ferromagnet. Temperature-dependent ellipsometric reflection measurements were performed in the energy range of 50 cm-1 - 5000 cm-1, on four faces of two samples of structurally anisotropic manganite, probing the 3. ab plane and c-axis of La1.2 Sr1.8 Mn2O7, a metallic ferromagnet, and 4. the ab plane and c-axis of PrSr2 Mn2O7, an insulating antiferromagnet. The optical conductivity for each of the first two samples has been deduced by a careful Kramers-Kronig analyis of the normal incidence reflectivity. For samples 3. and 4. the optical conductivity has been deduced by inversion of the ellipsometric constants, and a careful subsequent fitting to account for their anisotropy. The transition temperatures and types of magnetic order for all samples have also been characterised by magnetisation measurements. Treatment of the surface is shown to be critical in reflectivity measurements by the observation of hugely contrasting spectra, measured from a polished sample of metallic-like La0.735 Ca0.256 MnO3, before and after annealing. Several features observed in the measurements, especially for the layered materials, are consistent with the idea that a polaron, or electron-lattice interaction, is hugely important in a description of the electron dynamics of these materials. The correlation between spectral features and the structural and magnetic properties of the materials is investigated, finding that the cause of charge transport modification seen in the metallic-like materials could be explained by either a polaron or localisation due to disorder.</p>

scholarly journals Temperature-dependent optical conductivity of layered LaSrFeO4

2013 ◽  
Vol 87 (20) ◽  
Author(s):  
J. Reul ◽  
L. Fels ◽  
N. Qureshi ◽  
K. Shportko ◽  
M. Braden ◽  
...  
Keyword(s):  
Optical Conductivity ◽  
Temperature Dependent

Manifestation of charge/orbital order and charge transfer in temperature-dependent optical conductivity of single-layered Pr0.5Ca1.5MnO4

2019 ◽  
Vol 31 (36) ◽  
pp. 365601
Author(s):  
Choirun Nisaa Rangkuti ◽  
Adam B Cahaya ◽  
Anugrah Azhar ◽  
Muhammad Aziz Majidi ◽  
Andrivo Rusydi
Keyword(s):  
Charge Transfer ◽  
Optical Conductivity ◽  
Temperature Dependent ◽  
Orbital Order

(111) Monocrystalline Nickel Films

1972 ◽  
Vol 30 ◽  
pp. 512-513
Author(s):  
T.E. Pratt ◽  
R.W. Vook
Keyword(s):  
Film Thickness ◽  
Deposition Rate ◽  
Room Temperature ◽  
Narrow Range ◽  
High Vacuum ◽  
Residual Pressure ◽  
Temperature Dependent ◽  
Deposition Parameters ◽  
Transmission Electron ◽  
Substrate Temperatures

(111) oriented thin monocrystalline Ni films have been prepared by vacuum evaporation and examined by transmission electron microscopy and electron diffraction. In high vacuum, at room temperature, a layer of NaCl was first evaporated onto a freshly air-cleaved muscovite substrate clamped to a copper block with attached heater and thermocouple. Then, at various substrate temperatures, with other parameters held within a narrow range, Ni was evaporated from a tungsten filament. It had been shown previously that similar procedures would yield monocrystalline films of CU, Ag, and Au.For the films examined with respect to temperature dependent effects, typical deposition parameters were: Ni film thickness, 500-800 A; Ni deposition rate, 10 A/sec.; residual pressure, 10-6 torr; NaCl film thickness, 250 A; and NaCl deposition rate, 10 A/sec. Some additional evaporations involved higher deposition rates and lower film thicknesses.Monocrystalline films were obtained with substrate temperatures above 500° C. Below 450° C, the films were polycrystalline with a strong (111) preferred orientation.

Sign in / Sign up

Export Citation Format

Share Document