Temat: 71.70.Gm - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: s-p-d-f Exchange Interactions in Mn and Eu Based IV-VI Semimagnetic Semiconductors
Autorzy:: Dietl, T.
Bauer, G.
Tematy:: 71.70.Gm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1921647.pdf Link otwiera się w nowym oknie
Opis:: We evaluated exchange integrals which describe the spin dependent coupling between effective mass electrons and localized spins in the IV-VI semi-magnetic semiconductors taking into account contributions from the direct Coulomb exchange as well as from the hybridization between band states and magnetic shells. The obtained constants compare favorably with the experimental values for both the Mn- and the Eu-based compounds. We also discuss some peculiarities of IV-VI semimagnetic semiconductors, which may render the virtual-crystal approximation invalid.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Double Exchange in Mixed-Valency Diluted Magnetic Semiconductors
Autorzy:: Blinowski, J.
Kacman, P.
Tematy:: 71.70.Gm
75.30.Et; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1947969.pdf Link otwiera się w nowym oknie
Opis:: The role of double-exchange, a non-Heisenberg spin-spin interaction between the magnetic ions of identical chemical nature but different charge states, in the mixed-valency diluted magnetic semiconductors is discussed. The mechanism correlates the spins of magnetic ions by virtual hopping of a d-electron from one ion to the other via the p-band states. We calculate the energy spectrum for pairs of magnetic ions within the charged ionic clusters stabilized by the charge-charge correlations, taking into account simultaneously both the double and the superexchange. The ferromagnetic, non-Heisenberg double exchange might compete with the Heisenberg-like, ferrimagnetic superexchange, thus resulting in canted alignments of ionic spins.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: s,p-d Exchange Constants of ZnFeTe Diluted Magnetic Semiconductor
Autorzy:: Mac, W.
Herbich, M.
Nguyen, The Khoi
Twardowski, A.
Shapira, Y.
Demianiuk, M.
Tematy:: 78.20.Ls
71.70.Gm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1933919.pdf Link otwiera się w nowym oknie
Opis:: Reflectance and degree of polarization of reflectance of the free exciton in Zn$\text{}_{1-x}$Fe$\text{}_{x}$Te (x ≈ 0.002) was measured at T = 1.9 K and magnetic field up to 5 T. Combining the exciton splitting with the magnetization data we estimated the exchange constant N$\text{}_{0}$(α-β) = 2.1 eV.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Exchange Integrals in Hg$\text{}_{0.95}$Mn$\text{}_{0.05}$Se Obtained by the Wave Shape Analysis of Shubnikov-de Haas Oscillations
Autorzy:: Dybko, K.
Kossut, J.
Tematy:: 72.20.My
71.70.Gm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1929722.pdf Link otwiera się w nowym oknie
Opis:: The Shubnikov-de Haas oscillations were measured in Hg$\text{}_{0.95}$Mn$\text{}_{0.05}$Se at liquid helium temperatures, in magnetic fields up to 13 tesla. The analysis of the experimental data was performed by means of the wave shape method. The dependence of effective g-factor of the conduction electrons and difference Dingle temperature on magnetic field was determined. Non-zero difference Dingle temperature is a clear evidence of spin dependent scattering in this material. The sp-d exchange constants consistent with extracted spin splitting and difference Dingle temperature, α = -0.39 ± 0.06 eV, β = 0.95 ± 0.07 eV, are in good agreement with the values obtained from magnetooptics.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Point-Contact Spectroscopy of Ce$\text{}_{1-x}$RE$\text{}_{x}$Ni$\text{}_{5}$ (RE = Pr, Nd)
Autorzy:: Kačmárová, T.
Reiffers, M.
Garcia Soldevilla, J.
Goméz Sal, J. C.
Espeso, J. I.
Blanco, J. A.
Tematy:: 73.40.Jn
71.70.Ch
71.70.Gm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2013409.pdf Link otwiera się w nowym oknie
Opis:: We report on the study of the electron-quasiparticle interaction function in Ce$\text{}_{1-x}$RE$\text{}_{x}$ Ni$\text{}_{5}$ (RE = Pr, Nd) pseudobinary compounds for x = 0, 0.2, 0.5, 0.8, and 1 measured by means of point-contact spectroscopy. The measured point-contact spectra (d$\text{}^{2}$V/dI$\text{}^{2}$ - directly proportional to the electron- quasiparticle interaction function) of the heterocontacts between Ce$\text{}_{1-x}$ RE$\text{}_{x}$Ni$\text{}_{5}$ and Cu in the ballistic regime are presented.zapisz i p
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Crystal Field Analysis of $Cr^{3+}$ Doped $SrAl_{2}O_{4}$ Spinel
Autorzy:: Stanciu, M.
Ciresan, M.
Avram, N.
Tematy:: 71.70.Ch
68.47.Jn
71.70.Gm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1791232.pdf Link otwiera się w nowym oknie
Opis:: The present work is devoted to the crystal field analysis of trivalent chromium doped in $SrAl_{2}O_{4}$ spinel in the frame of the exchange charge model of crystal field. Using the shell model and pair approximation, we optimize the geometric structure of the crystal. The approach enables the modeling of the crystal field parameters and thus calculates the energy level scheme of $Cr^{3+}$ ions in spinel $SrAl_{2}O_{4}$. The obtained results are compared with experimental data and discussed.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Mn Impurity in GaN Studied by Electron Paramagnetic Resonance
Autorzy:: Wołoś, A.
Palczewska, M.
Wilamowski, Z.
Kamińska, M.
Twardowski, A.
Boćkowski, M.
Grzegory, I.
Porowski, S.
Tematy:: 71.55.-i
71.55.Eq
71.70.Gm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2036027.pdf Link otwiera się w nowym oknie
Opis:: We present the results of electron paramagnetic resonance investigations of GaN bulk crystals doped with Mn. The EPR experiment shows the Mn$\text{}^{2+}$ resonance in all the investigated n-type crystals, while in highly resistive samples extra doped with Mg acceptor the Mn$\text{}^{2+}$ resonance decreases. This is a consequence of the location of Mn acceptor level in GaN band gap. The analysis of the spin relaxation times reveals the Korringa scattering as the dominating spin relaxation mechanism in n-type GaN:Mn crystals. The effective exchange constant determined from spin relaxation rate temperature dependence is of the order of 14 meV.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: s,p-d Exchange Constants of CdFeSe Semimagnetic Semiconductor
Autorzy:: Arciszewska, M.
Pakuła, K.
Perez, I.
Twardowski, A.
Tematy:: 71.25.Tn
71.70.Gm
71.35.+z; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1886791.pdf Link otwiera się w nowym oknie
Opis:: We report determination of s, p-d exchange constants for hexagonal CdFeSe combining exciton splitting and magnetization measurements performed on the same samples.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Electronic Structure of Doped La-Mn-O Perovskites
Autorzy:: Demeter, M.
Neumann, M.
Galakhov, V. R.
Ovechkina, N. A.
Kurmaev, E. Z.
Labachevskaya, N. I.
Tematy:: 79.70.+q
71.70.Gm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2014437.pdf Link otwiera się w nowym oknie
Opis:: The electronic structure of the doped perovskite manganese oxides La$\text{}_{1-x}$Sr$\text{}_{x}$MnO$\text{}_{3}$ and La$\text{}_{1-x}$Ba$\text{}_{x}$MnO$\text{}_{3}$ has been investigated by X-ray photoelectron and X-ray emission spectroscopy. By comparing the O K$\text{}_{α}$ and Mn L$\text{}_{α}$ X-ray emission spectra with the valence band X-ray photoelectron spectra we could localize the Mn 3d and O 2p states into the valence band. Our data are compared with previous band structure calculations. The value of the Mn 3s splitting does not change with Sr-doping in the concentration region from x=0.0 till x=0.3. This shows that the doping holes have mainly oxygen p character. The large value of the splitting indicates that the 3d electrons are in the high-spin state.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Distance Dependence of the Mn-Mn Exchange Interaction in IV-VI Semimagnetic Semiconductors
Autorzy:: Łusakowski, A.
Górska, M.
Tematy:: 71.70.Gm
75.30.Hx; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2036858.pdf Link otwiera się w nowym oknie
Opis:: In the present paper we calculate the exchange interaction between two manganese ions in IV-VI semiconductors with the rocksalt structure. The method of calculations is based on the fourth order perturbation theory with respect to hybridization between band states and localized d orbitals of Mn ions. This hybridization is described by three Harrison integrals: V$\text{}_{pdσ}$,V$\text{}_{pdπ}$, and V$\text{}_{sdσ}$. The band states of IV-VI semiconductor are obtained from the semiempirical tight binding model built from s and p orbitals of cations and anions. The resulting exchange term in the Hamiltonian is of the form -Σ$\text{}_{i,j=xyz}$J$\text{}_{ ij}$Ŝ$\text{}_{i}^{1}$Ŝ$\text{}_{j}^{2}$, however nondiagonal terms of the exchange integral tensor J$\text{}_{i≠j}$ are very small. The dependence of J$\text{}_{ij}$ on the Mn-Mn distance is non-monotonic. We also discuss the influence of the local crystal deformations on the exchange integral.
Dostawca treści:: Biblioteka Nauki

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