Temat: 71.20.-b - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Electronic Structure and Martensitic Transformation in Ni$\text{}_{2}$ MnGa Heusler Alloy
Autorzy:: Pugaczowa-Michalska, M.
Tematy:: 71.20.-b; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2011090.pdf Link otwiera się w nowym oknie
Opis:: The electronic structure of the Ni$\text{}_{2}$MnGa Heusler alloy has been investigated for martensitic transformation β$\text{}_{1}$ → β'$\text{}_{1}$ → β"$\text{}_{1}$ → β'''$\text{}_{1}$ by the self-consistent TB-LMTO method. The distortion influences the shape of the densities of states. The β$\text{}_{1}$ is the most stable phase. We present the values of total and local magnetic moments for all phases of Ni$\text{}_{2}$MnGa alloy.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: The Electronic Structure and Specific Heat of $YNi_4Si$
Autorzy:: Pugaczowa-Michalska, M.
Falkowski, M.
Kowalczyk, A.
Timko, M.
Reiffers, M.
Mihalik, M.
Šebek, J.
Šantava, E.
Tematy:: 71.20.Be
71.20.-b
65.40.-b; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1813671.pdf Link otwiera się w nowym oknie
Opis:: The studies of the electronic structure and the specific heat of $YNi_4Si$ are reported. Below the Fermi energy $(E_F)$ the density of states contains mainly the 3d states of Ni, which hybridized with 4d states of Y and 3p states of Si. The theoretical electronic specific heat coefficient (12.32 mJ/(mol $K^2$)) obtained for equilibrium lattice parameters and the experimental value (13 mJ/(mol $K^2$)) are in a reasonable agreement.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Band Gap Stability in Kondo Insulators
Autorzy:: Ślebarski, A.
Jezierski, A.
Zygmunt, A.
Tematy:: 71.20.-b
71.20.Eh; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2011220.pdf Link otwiera się w nowym oknie
Opis:: We report on magnetic measurements and electronic structure investigations of CeNiSn and CeRhSb. Both belong to the group of Kondo insulators. The magnetic susceptibility shows the nonmagnetic ground state for these compounds and their alloys. The 3d X-ray photoemission spectroscopy spectra show evidence for the mixed valence state of Ce in CeRhSb alloys, as also seen for CeNiSn, whereas the spectra for the La substituted (Ce,La)NiSn compounds show only evidence for a pure Ce$\text{}^{3+}$ ground state. We suggest the presence of Kondo-hole states in (Ce,La)RhSb. The location of the pseudogap in CeRhSb varies with the number of free electron, the valence of Ce, and the f-d hybridization. We discuss the similar crystallographic properties and the closed electronic structures of ZrNiSn-type semi-Heusler alloys and CeNiSn-type Kondo insulators.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Effect of Al Substitution on the Electronic and Magnetic Properties of GdCo$\text{}_{5}$
Autorzy:: Szajek, A.
Malinowski, W. L.
Tematy:: 71.20.-b
71.20.Eh; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2030516.pdf Link otwiera się w nowym oknie
Opis:: Experimental data show that aluminium doped RCo$\text{}_{5}$ systems crystallize in CaCu$\text{}_{5}$-type structure for most of the rare-earth elements (R). Al impurities randomly occupy one of the two possible positions (2c and 3g) and there is a critical concentration of Al, x$\text{}_{c}$=2.0, for RCo$\text{}_{5-x}$Al$\text{}_{x}$ when the Co sublattice becomes nonmagnetic. The ab initio self-consistent calculations show strong dependence of magnetic properties of GdCo$\text{}_{5-x}$Al$\text{}_{x}$ on concentration of Al and position of the impurities in the unit cell, furthermore to fulfil experimental observation of existence of critical concentration, x$\text{}_{c}$=2.0, the Al impurities should prefer 3g positions otherwise the magnetic moments on Co atoms do not vanish.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Effect of Alloying with Ca in LaMnO$\text{}_{3}$ System Studied by KKR-CPA Method and Giant Magnetoresistance
Autorzy:: Tobola, J.
Kaprzyk, S.
Pierre, J.
Tematy:: 71.20.-b
71.20.Lp; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1964825.pdf Link otwiera się w nowym oknie
Opis:: La$\text{}_{1-x}$ Ca$\text{}_{x}$MnO$\text{}_{3}$ perovskites show semiconducting properties in the paramagnetic range. The gap is reduced near x=0.33, where ferromagnetic ordering is observed. The ferromagnetic ordering then induces a semiconductor-metal transition, and gives rise to a giant magnetoresistance effect. The ground state electronic structure calculations were done with KKR-CPA method for hypothetical cubic and ferromagnetic LaMnO$\text{}_{3}$ and CaMnO$\text{}_{3}$ compounds, as well as for disordered La$\text{}_{1-x}$Ca$\text{}_{x}$MnO$\text{}_{3}$ (x=0.33, 0.4, 0.5) alloys with real crystal data. As a result, we get a magnetic moment per formula 4.00μ$\text{}_{B}$ and 3.00μ$\text{}_{B}$ and half-metallic behaviour for end-compounds, respectively. In the ferromagnetic region a linear decrease in the magnetic moment of La$\text{}_{1-x}$Ca$\text{}_{x}$MnO$\text{}_{3}$ is observed, together with the decrease in the gap width for spin-down carriers, if doping Ca in La$\text{}_{1-x}$Ca$\text{}_{x}$MnO$\text{}_{3}$. A simple model is developed, which describes magnetic and transport properties as resulting from an exchange-induced band-crossing semiconductor-metal transition, as for instance in EuO.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Ellipsometric Studies of NdMnO$\text{}_{3}$ Single Crystals
Autorzy:: Babonas, G. J.
Reza, A.
Szymczak, R.
Baran, M.
Shiryaev, S.
Fink-Finowicki, J.
Szymczak, H.
Tematy:: 71.20.-b
78.20.Ci; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2037130.pdf Link otwiera się w nowym oknie
Opis:: Ellipsometric studies of NdMnO$\text{}_{3}$ single crystals of orthorhombic symmetry were carried out in the spectral range 0.5-5.0 eV. Experimental data, which were obtained on the (001)$\text{}_{pc}$-type planes of pseudo-cubic system, were analyzed in the model of biaxial crystal. For the first time, three componentsε$\text{}_{x}$,ε$\text{}_{y}$,ε$\text{}_{z}$ of the effective dielectric function for manganites of orthorhombic symmetry were determined. From ellipsometric data, the spectra of optical conductivity and loss function were also calculated and considered. The fine structure of the spectra and optical anisotropy was the basis for discussion of the microscopic origin of the optical transitions responsible for the optical features. The electronic excitations due to dipole-forbidden spin-allowed transitions of the d-d-type in Mn-ions, f-f-type in Nd-ions and charge-transfer 2p(O)-3d(Mn) transitions were taken into account. The data for NdMnO$\text{}_{3}$ were compared with those obtained for other related undoped and doped single crystals of perovskite-type structure, LaMnO$\text{}_{3}$, (LaBa)(MnCo)O$\text{}_{3}$ and (LaCa)CoO$\text{}_{3}$.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Electronic and Magnetic Properties of $ThCo_4B$
Autorzy:: Szajek, A.
Tematy:: 71.20.-b
75.20.Hr; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1813651.pdf Link otwiera się w nowym oknie
Opis:: $ThCo_4B$ compound crystallizes in the hexagonal $CeCo_4B$ type structure. The electronic structure is calculated based on full-potential local-orbital full-relativistic method. The ab initio calculations showed that small magnetic moments (≈0.1 $μ_B$/atom) are formed on Th and B atoms, antiparallel to the moments on Co atoms equal to 1.55 and 0.43 $μ_B$/atom for Co(2c) and Co(6i), respectively. The densities of states at the Fermi level are equal to 1.3 and 5.4 states/(eV spin f.u.) for spin up and down, respectively. These values are predominated by Co(3d) electrons.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Electronic Structure of Zinc-Blende Zn$\text{}_{0.5}$Co$\text{}_{0.5}$Se: Theoretical Study
Autorzy:: Hołda, A.
Markowski, R.
Dębowska, D.
Kisiel, A.
Zimnal-Starnawska, M.
Piacentini, M.
Zema, N.
Lama, F.
Tematy:: 71.20.-b
71.20.Cf
71.70.-d; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1950806.pdf Link otwiera się w nowym oknie
Opis:: In this paper we present partial densities of states for spin-polarized antiferromagnetic phase of Zn$\text{}_{0.5}$Co$\text{}_{0.5}$Se as well as schematic layouts of the bands, obtained using the ab initio self-consistent semi-relativistic linear muffin tin orbital method. We also present, from theoretical point of view, the analysis of influence of the transition metal cobalt on the electronic structure of a pure ZnSe.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Electronic Structure of Zinc-Blende Zn$\text{}_{0.5}$V$\text{}_{0.5}$Se: Theoretical Study
Autorzy:: Markowski, R.
Hołda, A.
Dębowska, D.
Kisiel, A.
Zimnal-Starnawska, M.
Piacentini, M.
Zema, N.
Lama, F.
Tematy:: 71.20.-b
71.70.-d
71.20.Cf; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1934068.pdf Link otwiera się w nowym oknie
Opis:: In this paper we present a comprehensive study of electronic structure of Zn$\text{}_{0.5}$V$\text{}_{0.5}$Se from the theoretical point of view. Partial and total density of states for spin-polarized antiferromagnetic phase of Zn$\text{}_{0.5}$V$\text{}_{0.5}$Se as well as schematic layouts of the bands have been obtained using the ab initio self-consistent semirelativistic linear muffin-tin orbital method.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Electronic Structure of Some Wurtzite Semiconductors: Hybrid Functionals vs. Ab Initio Many Body Calculations
Autorzy:: Kaczkowski, J.
Tematy:: 71.15.Mb
71.20.-b
71.20.Nr; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1427431.pdf Link otwiera się w nowym oknie
Opis:: Using the first-principles projector augmented wave method, the structural and electronic properties of wurtzite crystals, AlN, GaN, InN and ZnO have been calculated. Different exchange-correlation approximations: LDA, LDA+U, GGA, GGA+U and hybrid Heyd-Scuseria-Ernzerhof method were used. We also present the values of band gap calculated within different GW approximations ($G_0W_0,$ $GW_0,$ $GW$ and $U+G_0W_0,$ the last one for materials with shallow d states). In case of structural parameters the best agreement with experiment was obtained for hybrid Heyd-Scuseria-Ernzerhof functional and in case of band gap the best agreement was for $GW$ and $U+G_0W_0$ approximation.
Dostawca treści:: Biblioteka Nauki

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