Temat: 71.30.+h - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Metal-Insulator Transition in Doped Semiconductors
Autorzy:: Jaroszyński, J.
Tematy:: 71.30.+h; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1888088.pdf Link otwiera się w nowym oknie
Opis:: A survey is given of different kinds of metal-insulator transitions (MIT) in doped semiconductors. The role of electron-electron Coulomb interactions and of disorder is discussed vis-a-vis millikelvin experimental results for semimagnetic semiconductors (SMSC) in the vicinity of MIT. Critical behavior of conductivity tensor components and dielectric susceptibility at the magnetic field-induced MIT in p-type Hg$\text{}_{1-x}$Mn$\text{}_{x}$Te is compatible with the model in which the MIT is a result of quantum localization driven by disorder-modified electron-electron interactions. At the same time the critical behavior of the Hall coefficient suggests that, in addition to electrons forming the Fermi liquid (FL) and undergoing localization at the MIT, there is certain a concentration of local electron moments, even on the metallic side of the MIT. The formation of these moments can presumably be described in terms of a disordered Hubbard-Mott model.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Correlation-Driven Metal-Insulator Transitions
Autorzy:: Honig, J. M.
Tematy:: 71.30.+h
71.45.Gm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2011236.pdf Link otwiera się w nowym oknie
Opis:: The effect of correlation-driven electronic transitions are described for the V$\text{}_{2}$O$\text{}_{3}$, NiS$\text{}_{2-x}$Se$\text{}_{x}$, and Fe$\text{}_{3}$O$\text{}_{4}$ systems. The various tranformations can all be rationalized in terms of elementary concepts pertaining to the Mott-Hubbard intraatomic electronic interactions or in terms of an order-disorder formalism involving Coulomb interactions among electrons on adjacent sites. Attention is directed to some outstanding issues that require further resolution.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Conductivity Near the Metal-to-Insulator Transition in Cd$\text{}_{1-x}$Mn$\text{}_{x}$Se:Sc
Autorzy:: Głód, P.
Sawicki, M.
Lenard, A.
Dietl, T.
Plesiewicz, W.
Tematy:: 71.30.+h
71.55.Jv; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1887158.pdf Link otwiera się w nowym oknie
Opis:: Earlier studies of transition metal impurities in II-VI compounds suggest that Sc acts as a resonant donor. We performed Hall effect and conductivity measurements of CdSe:Sc and Cd$\text{}_{0.95}$Mn$\text{}_{0.05}$Se:Sc. The results, particularly the critical concentration of the metal-to-insulator transition, turned out to be similar to those obtained previously for Cd$\text{}_{1-x}$Mn$\text{}_{x}$Se doped with hydrogenic-like impurities, such as In and Ga. Therefore, if the ground state of Sc impurity is indeed located above the bottom of the conduction band, our data demonstrate that the metal-to-insulator transition is primarily driven by the scattering, i.e. it corresponds to the Anderson localization.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Global Structure of the Falicov-Kimball Model Ground State Phase Diagram
Autorzy:: Lach, J.
Łyżwa, R.
Jędrzejewski, J.
Tematy:: 75.30.Mb
71.30.+h; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1929588.pdf Link otwiera się w nowym oknie
Opis:: The two-state spinless Falicov-Kimball model on a one-dimensional lattice is studied by means of well-controlled numerical procedures. Restricted phase diagrams in the grand-canonical ensemble and at zero temperature are constructed. The evolution of these phase diagrams, as the interaction parameter U is varied, including the band structures corresponding to configurations of localized particles (ions) and densities of mobile particles (electrons), is monitored. The changes observed enable us to draw conclusions for the global structure of the phase diagram and to make a qualitative plot of such a diagram. Particular attention is paid to the possibility of conductor-insulator transitions. The results obtained suggest that the system is an insulator for all U only if the electron and ion densities ρ$\text{}_{e}$,ρ$\text{}_{i}$ satisfy the conditions: ρ$\text{}_{e}$ + ρ$\text{}_{i}$ = 1, |ρ$\text{}_{i}$ - 1/2| ≤ δ < 1/2. For all other pairs (ρ$\text{}_{e}$,ρ$\text{}_{i}$) there is a critical U at which the system undergoes a conductor-insulator transition.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Infrared Reflection of $MnTe_2$ under High Pressure
Autorzy:: Mita, Y.
Ishida, Y.
Kobayashi, M.
Endo, S.
Tematy:: 71.30.+h
78.30.-j; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1813955.pdf Link otwiera się w nowym oknie
Opis:: The IR reflection measurements of $MnTe_2$ were performed at room temperature under various pressures. It is observed that the reflectivity increases at the pressure range of 8-25 GPa and becomes almost constant at the higher pressure. The carrier concentrations obtained from the reflectivity spectra at the highest pressure region are the order of $10^{22} cm^{-3}$. Therefore it is concluded that pressure-induced semiconductor-metal transition occurs at the pressure range of 8-25 GPa.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Correlation between Magnetic Phases and Insulator-Metal Transition in La$\text{}_{1}\text{}_{/}\text{}_{3}$ Nd$\text{}_{1}\text{}_{/}\text{}_{3}$ Ca$\text{}_{1}\text{}_{/}\text{}_{3}$ MnO$\text{}_{3}$ Perovskite
Autorzy:: Baszyński, J.
Idzikowski, B.
Toliński, T.
Hoser, A.
Tematy:: 71.30.+h
75.25.+z; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2013369.pdf Link otwiera się w nowym oknie
Opis:: The La$\text{}_{1}\text{}_{/}\text{}_{3}$ Nd$\text{}_{1}\text{}_{/}\text{}_{3}$ Ca$\text{}_{1}\text{}_{/}\text{}_{3}$ MnO$\text{}_{3}$ ceramic perovskites are investigated using the neutron diffraction technique and resistance measurements in the temperature range from 260 K down to 5 K. We have found that the integrated intensity of the antiferromagnetic peaks was growing with decreasing temperature and reached the maximum at a temperature about 20 K lower than that of the semiconductor-metal transition and did not vanish at 5 K. The semiconductor-metal transition is correlated with the temperature of the maximum of the lattice c-parameter and the percolation of ferromagnetic domains. Our results suggest that although the ferromagnetic long-range order is established through the semiconductor-metal transition induced percolation network, locally the antiferromagnetic correlation can remain.zapisz
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Neutron Diffraction Study of Ferromagnetic Ordering in La$\text{}_{1}\text{}_{/}\text{}_{3}$ Nd$\text{}_{1}\text{}_{/}\text{}_{3}$ Ca$\text{}_{1}\text{}_{/}\text{}_{3}$ MnO$\text{}_{3}$ Induced by Electric Field
Autorzy:: Baszyński, J.
Idzikowski, B.
Toliński, T.
Hoser, A.
Tematy:: 71.30.+h
75.25.+z; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2013692.pdf Link otwiera się w nowym oknie
Opis:: We used the neutron diffraction technique to study the ferromagnetic ordering process in La$\text{}_{1}\text{}_{/}\text{}_{3}$ Nd$\text{}_{1}\text{}_{/}\text{}_{3}$ Ca$\text{}_{1}\text{}_{/}\text{}_{3}$ MnO$\text{}_{3}$ induced by the short impulse of the external electric field E=4 V/cm at a magnetic field H=1.5 T. Our sample was prepared by the standard solid-state reaction. The diffraction measurements at 4 K, carried out for the neutron wavelength λ=0.2442 nm, have revealed the orthorhombic perovskite structure with the unit-cell parameters: a=0.5480 nm, b=0.5550 nm and c=0.7737 nm. We observed that a short impulse of the electric field develops the ferromagnetic ordering in a similar way as the magnetic field up to 4 T. We assume that the increased ferromagnetic ordering induced by the external electric field at a given magnetic field has the same physical origin as in the case of the Zener double exchange. The effect is confirmed by magnetic moment measurements using vibrating sample magnetometer.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Phase Diagram of Metal-Insulator Transition in System with Anderson-Hubbard Centers
Autorzy:: Skorenkyy, Yu.
Didukh, L.
Kramar, O.
Dovhopyaty, Yu.
Tematy:: 75.10.Lp
71.30.+h; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1418528.pdf Link otwiera się w nowym oknie
Opis:: The model of a strongly correlated system in which periodically spaced Anderson-Hubbard centers are introduced into narrow-band metal is considered. Besides the interactions between localized magnetic moments and strong on-site Coulomb interaction, the model takes into account the hybridization of localized and band states. To study the effect of the lattice deformation on the electrical properties of the system, the phonon term and elastic energy have been taken into account. Green functions for band and localized electrons have been found. On this base, the energy spectrum has been investigated as a function of model parameters, temperature and external pressure. The criterion of the metal-insulator transition for an integer value of electron concentration has been derived and the phase diagram of the metal-insulator transition has been built.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Comparative Study of the Electronic Structures of $Fe_3O_4$ and $Fe_2SiO_4$
Autorzy:: Piekarz, P.
Oleś, A.
Parlinski, K.
Tematy:: 71.27.+a
71.30.+h
71.38.-k; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1536886.pdf Link otwiera się w nowym oknie
Opis:: The electronic properties of two spinels $Fe_3O_4$ and $Fe_2SiO_4$ are studied by the density functional theory. The local Coulomb repulsion U and the Hund exchange J between the 3d electrons on iron are included. For U = 0, both spinels are half-metals, with the minority $t_{2g}$ states at the Fermi level. Magnetite remains a metal in a cubic phase even at large values of U. The metal-insulator transition is induced by the $X_3$ phonon, which lowers the total energy and stabilizes the charge-orbital ordering. $Fe_2SiO_4$ transforms to a Mott insulating state for U > 2 eV with a gap $Δ_g$ ~ U. The antiferromagnetic interactions induce the tetragonal distortion, which releases the geometrical frustration and stabilizes the long-range order. The differences of electronic structures in the high-symmetry cubic phases and the distorted low-symmetry phases of both spinels are discussed.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Non-Fermi Liquid Behavior of Correlated Fermions in Applied Field
Autorzy:: Korbel, P.
Spałek, J.
Wójcik, W.
Tematy:: 71.27.+a
71.30.+h
71.10.Fd; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1964622.pdf Link otwiera się w nowym oknie
Opis:: We have determined an instability of the Fermi-liquid state of almost localized fermions in an applied magnetic field. It is proposed that a transition to a strongly correlated fermions (statistical-spin-liquid) state takes place at that point. The resultant magnetization curve and the field dependence of the specific heat are calculated and compared with those for CeRu$\text{}_{2}$Si$\text{}_{2}$.
Dostawca treści:: Biblioteka Nauki

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