Coexistence of Shallow and Localized Donor Centers in Bulk GaN Crystals Studied by High-Pressure Raman Spectroscopy

1996 ◽  
Vol 449 ◽  
Author(s):  
P. Perlin ◽  
T. Suski ◽  
A. Polian ◽  
J. C. Chervin ◽  
W. Knap ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
High Pressure ◽  
High Pressures ◽  
Nitrogen Vacancy ◽  
Donor Center ◽  
Initial Value ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Bulk Gan ◽  
Donor State

ABSTRACTCharacter of the metal-insulator transition which occurs at about 23 GPa in bulk GaN crystals has been studied by means of high pressure Raman spectroscopy. The related freeze-out of electrons is caused by the localized donor state formed by most likely oxygen and emerging at high pressures to the band gap of GaN. As a result, the electron concentration drops from its initial value of 5.1019 cm-3 to about 3. 1018 cm-3. These remaining electrons originate likely from another donor center with effective mass character, probably carbon. The obtained results raise a question whether the nitrogen vacancy is abundant enough to be observed in bulk GaN crystals.

scholarly journals Large Fermi Surface of Heavy Electrons at the Border of Mott Insulating State in NiS2

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
S. Friedemann ◽  
H. Chang ◽  
M. B. Gamża ◽  
P. Reiss ◽  
X. Chen ◽  
...  
Keyword(s):  
High Pressure ◽  
Fermi Surface ◽  
Quantum Physics ◽  
Mott Transition ◽  
Electrostatic Repulsion ◽  
Strong Correlations ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Alternative Scenarios ◽  
Rule Out

Abstract One early triumph of quantum physics is the explanation why some materials are metallic whereas others are insulating. While a treatment based on single electron states is correct for most materials this approach can fail spectacularly, when the electrostatic repulsion between electrons causes strong correlations. Not only can these favor new and subtle forms of matter, such as magnetism or superconductivity, they can even cause the electrons in a half-filled energy band to lock into position, producing a correlated, or Mott insulator. The transition into the Mott insulating state raises important fundamental questions. Foremost among these is the fate of the electronic Fermi surface and the associated charge carrier mass, as the Mott transition is approached. We report the first direct observation of the Fermi surface on the metallic side of a Mott insulating transition by high pressure quantum oscillatory measurements in NiS2. Our results point at a large Fermi surface consistent with Luttinger’s theorem and a strongly enhanced quasiparticle effective mass. These two findings are in line with central tenets of the Brinkman-Rice picture of the correlated metal near the Mott insulating state and rule out alternative scenarios in which the carrier concentration vanishes continuously at the metal-insulator transition.

Suppression of Metal–Insulator Transition in PrRu4P12under High Pressure Studied by Infrared Spectroscopy

2011 ◽  
Vol 80 (Suppl.A) ◽  
pp. SA092 ◽  
Author(s):  
Hidekazu Okamura ◽  
Ikuo Matsutori ◽  
Akira Takigawa ◽  
Ko Shoji ◽  
Kazuaki Miyata ◽  
...  
Keyword(s):  
High Pressure ◽  
Infrared Spectroscopy ◽  
Insulator Transition ◽  
Metal Insulator Transition ◽  
Metal Insulator

Spectroscopy at High Pressures—Status Report and Update of Instrumental Techniques

1974 ◽  
Vol 28 (6) ◽  
pp. 505-516 ◽  
Author(s):  
John R. Ferraro ◽  
Louis J. Basile
Keyword(s):  
Raman Spectroscopy ◽  
High Pressure ◽  
High Pressures ◽  
Status Report ◽  
Future Outlook ◽  
Optical Link ◽  
Interferometric Technique ◽  
Pressure Calibration ◽  
Calibration Methods ◽  
Optical Pressure

A status report and update of the instrumentation necessary to obtain spectra of molecules at high pressures are presented. The optical pressure cells used, the spectrophotometer needed to obtain the spectra, the optical link between the two, high pressure spectroscopic windows, pressure calibration methods, and future outlook of the technique will be determined. The use of the high pressure cells with the interferometric technique and for Raman spectroscopy is outlined.

Metal–insulator transition under high pressure in

2005 ◽  
Vol 359-361 ◽  
pp. 886-888 ◽  
Author(s):  
Hiroyuki Hidaka ◽  
Ikuma Ando ◽  
Hisashi Kotegawa ◽  
Tatsuo C. Kobayashi ◽  
Hisatomo Harima ◽  
...  
Keyword(s):  
High Pressure ◽  
Insulator Transition ◽  
Metal Insulator Transition ◽  
Metal Insulator

A Study for N2 Coherent Anti-Stokes Raman Spectroscopy Thermometry at High Pressure

1983 ◽  
Vol 37 (6) ◽  
pp. 508-512 ◽  
Author(s):  
Haruhiko Kataoka ◽  
Shiro Maeda ◽  
Chiaki Hirose ◽  
Koichi Kajiyama
Keyword(s):  
Raman Spectroscopy ◽  
High Pressure ◽  
High Temperature ◽  
Pressure Range ◽  
High Pressures ◽  
Band Width ◽  
Maximum Height ◽  
Temperature Determination ◽  
Engine Cylinder ◽  
Anti Stokes

N2 coherent anti-Stokes Raman spectroscopy (CARS) thermometry over a pressure range 1 to 50 atm has been studied. The CARS profile at high pressure and high temperature was recorded by using the ignition inside a running engine cylinder. The observed Q-branch profile was theoretically fitted by incorporating the collisional narrowing effect, serving for the temperature determination at various pressures. Because of the narrowing effect, the apparent band width showed little change with pressure above 5 atm in general. It has been suggested that the band width at 1/5 of the maximum height can be a useful measure of temperature, while the usual half-width turns out to be hardly practicable at high pressures.

p-Aminobenzoic acid polymorphs under high pressures

RSC Advances ◽  
2014 ◽  
Vol 4 (30) ◽  
pp. 15534-15541 ◽  
Author(s):  
Tingting Yan ◽  
Kai Wang ◽  
Defang Duan ◽  
Xiao Tan ◽  
Bingbing Liu ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
High Pressure ◽  
Diamond Anvil Cell ◽  
High Pressures ◽  
Aminobenzoic Acid ◽  
Aminobenzoic Acids ◽  
Diamond Anvil

The effect of high pressure on two forms (α, β) of p-aminobenzoic acids (PABA) is studied in a diamond anvil cell using in situ Raman spectroscopy.

Spin-state-driven metal-insulator transition in(La,Sr)CoO3under high-pressure

2007 ◽  
Vol 75 (18) ◽  
Author(s):  
R. Lengsdorf ◽  
J.-P. Rueff ◽  
G. Vankó ◽  
T. Lorenz ◽  
L. H. Tjeng ◽  
...  
Keyword(s):  
High Pressure ◽  
Spin State ◽  
Insulator Transition ◽  
Metal Insulator Transition ◽  
Metal Insulator

HIGH PRESSURE STUDY OF NOVEL ELECTRONIC PROPERTIES IN Sr2Fe(W1-xMox)O6 NEAR METAL-INSULATOR TRANSITION

2007 ◽  
Vol 21 (18n19) ◽  
pp. 3279-3284
Author(s):  
G. OOMI ◽  
S. KAJI ◽  
Y. TOMIOKA ◽  
Y. TOKURA
Keyword(s):  
High Pressure ◽  
Double Perovskite ◽  
Insulator Transition ◽  
Metallic State ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Electrical Resistivities ◽  
Insulating Properties ◽  
High Pressure Study ◽  
Variable Range Hopping Conduction

Electrical resistivities of double perovskite oxides Sr 2 Fe ( W 1-x Mo x) O 6 have been measured at high pressure and high magnetic field to elucidate the transport properties of these materials. It is found that the main mechanism of the transport in the semiconducting phase is variable range hopping conduction and the insulating properties are suppressed by high pressure to show a crossover to metallic state. The magnetoresistances of these oxides are revealed to decrease at high pressure above 1 GPa. Extremely large Grüneisen parameters are found near x = 0.2, where the metal-insulator transition occurs. The origin for these properties will be briefly discussed in connection with the phase diagram.

Metal—insulator transition of CuIr2(S,Se)4 under high pressure

1998 ◽  
Vol 177-181 ◽  
pp. 1363-1364 ◽  
Author(s):  
J. Tang ◽  
T. Matsumoto ◽  
T. Furubayashi ◽  
T. Kosaka ◽  
S. Nagata ◽  
...  
Keyword(s):  
High Pressure ◽  
Insulator Transition ◽  
Metal Insulator Transition ◽  
Metal Insulator
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