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Wyszukujesz frazę "T. G." wg kryterium: Autor


Tytuł:
s-p-d-f Exchange Interactions in Mn and Eu Based IV-VI Semimagnetic Semiconductors
Autorzy:
Dietl, T.
Bauer, G.
Powiązania:
https://bibliotekanauki.pl/articles/1921647.pdf
Data publikacji:
1992-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.70.Gm
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.
Źródło:
Acta Physica Polonica A; 1992, 82, 5; 729-732
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Search for Dimensional Effects in Spin-Glass Transition in Thin Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te Multilayers
Autorzy:
Sawicki, M.
Dietl, T.
Skośkiewicz, T.
Karczewski, G.
Wojtowicz, T.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1943818.pdf
Data publikacji:
1995-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Rr
75.50.Lk
75.30.Kz
75.50.-y
Opis:
SQUID magnetic measurements of CdTe/Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te, x ≃ 0.5, multi-layers with different CdMnTe layer thickness w reveal the persistence of the spin-glass irreversibilities down to ≃ 16 Å thin layers, i.e., well beyond the previously postulated 40 Å as a quasi-2D threshold. The freezing temperature T$\text{}_{f}$ is found to be a monotonic function of w, and it obeys a scaling law T$\text{}_{f}$ ∝ w$\text{}^{a}$, with a 0.8 similar to that for canonical spin-glasses. Magnetic properties of all studied structures are found to be independent of the orientation of the magnetic field.
Źródło:
Acta Physica Polonica A; 1995, 88, 5; 1038-1042
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Search for Dimensionality Crossover of Spin-Glass Freezing in Superlattices of Cd$\text{}_{0.50}$Mn$\text{}_{0.50}$Te/CdTe
Autorzy:
Sawicki, M.
Dietl, T.
Karczewski, G.
Wojtowicz, T.
Kossut, J.
Skośkiewicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/1952078.pdf
Data publikacji:
1996-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.-y
75.50.Rr
75.50.Lk
Opis:
SQUID measurements of the time decay of the thermoremanent magnetization (field-cooled in 1000 Oe) at long time scale, 10$\text{}^{2}$ < t < 10$\text{}^{5}$ s, are presented for MBE grown Cd$\text{}_{0.50}$Mn$\text{}_{0.50}$Te. We found that for both thin (32 Å) and thick (2500 Å) layers the spin-glass dynamics is characterized by a similar value of k = -(1/T$\text{}_{f}$)(dT$\text{}_{f}$/dlogt) > 0.05, indicating the absence of the phase transition at nonzero temperature under the experimental conditions.
Źródło:
Acta Physica Polonica A; 1996, 90, 5; 919-922
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Second Harmonic Generation in Spin-Glass Microstructures and Fabrication of Microstructures in IV-VI Epilayers
Autorzy:
Grabecki, G.
Dietl, T.
Cieplak, Marek
Plesiewicz, W.
Lenard, A.
Skośkiewicz, T.
Kamińska, E.
Piotrowska, A.
Żarecka, R.
Springholz, G.
Bauer, G.
Powiązania:
https://bibliotekanauki.pl/articles/1929753.pdf
Data publikacji:
1993-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Jv
Opis:
We studied magnetoconductance of two different mesoscopic systems: microregions containing two-dimensional electron gas adjacent to a grain-boundary plane in bicrystals of Hg$\text{}_{0.79}$Cd$\text{}_{0.19}$Mn$\text{}_{0.02}$Te and photolithographically patterned microstructures of Pb$\text{}_{1-x}$Mn$\text{}_{x}$Se. In both systems universal conductance fluctuations and generation of the second-harmonic voltage were observed at T ≤ 1 K. Moreover, in the former system the second harmonic signal exhibited distinct rise when the sample was cooled below the spin-glass freezing temperature (100 mK).
Źródło:
Acta Physica Polonica A; 1993, 84, 4; 781-784
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Megagauss Cyclotron Resonance and Quantum Hall Effect of 2D Electron Gas in HgCdMnTe
Autorzy:
Grabecki, G.
Takeyama, S.
Dietl, T.
Takamasu, T.
Shimamotο, Y.
Miura, N.
Powiązania:
https://bibliotekanauki.pl/articles/1933749.pdf
Data publikacji:
1995-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.25.Hc
73.50.Fq
73.20.Dx
73.40.Lq
Opis:
Two-dimensional electron gas adjacent to a grain boundary in bicrystal of narrow-gap semiconductor p- Hg$\text{}_{0.79}$Cd$\text{}_{0.19}$Mn$\text{}_{0.02}$Te has been studied under ultra strong impulse magnetic fields (up to 140 T). Both cyclotron resonance and quantum Hall effect are measured for the same samples. The values of the resonance fields point to strong nonparabolicity. A broadening of the line is interpreted in terms of an intersubband mixing that occurs for the upper Landau level. A steep increase in the linewidth in the field range 20-30 T, which coincides with a strong decrease in the Hall resistance is assigned to the field-induced metal-insulator transition in our system.
Źródło:
Acta Physica Polonica A; 1995, 88, 4; 731-734
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Conductance Anomalies in Strained Quantum Wires: the Case of PbSe and PbTe
Autorzy:
Grabecki, G.
Wróbel, J.
Dietl, T.
Sawicki, M.
Skośkiewicz, T.
Papis, E.
Kamińska, E.
Piotrowska, A.
Frank, N.
Ueta, Y.
Sprinholtz, G.
Bauer, G.
Powiązania:
https://bibliotekanauki.pl/articles/1950800.pdf
Data publikacji:
1996-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Jv
Opis:
We show that conducting edge channels are formed in free standing wires of PbSe/BaF$\text{}_{2}$ and PbTe/BaF$\text{}_{2}$ as temperature is lowered. The effect results from spatially inhomogeneous strain caused by a difference between the thermal expansion coefficients of the epilayer and the substrate. The presence of the edge channels can explain anomalous mesoscopic effects observed previously in these wires.
Źródło:
Acta Physica Polonica A; 1996, 90, 4; 797-800
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of Ballistic Transport in Wires of n-PbTe
Autorzy:
Grabecki, G.
Wróbel, J.
Dietl, T.
Papis, E.
Kamińska, E.
Piotrowska, A.
Ueta, Y.
Sprinholtz, G.
Bauer, G.
Powiązania:
https://bibliotekanauki.pl/articles/1968110.pdf
Data publikacji:
1997-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.61.-r
73.23.Ad
73.50.Dn
Opis:
We present results of magnetotransport studies on quantum wires of submicron PbTe epilayers, fabricated by means of electron beam lithography and dry etching. When the wire width is reduced down to 1 μm, the transition from diffusive to ballistic regime is observed. Effects associated with collimation and boundary scattering are found in the Hall, longitudinal, and van der Pauw magnetoresistance for wires and junctions in the shape of a cross.
Źródło:
Acta Physica Polonica A; 1997, 92, 4; 789-792
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mesoscopic Phenomena in Microstructures of IV-VI Epilayers
Autorzy:
Grabecki, G.
Dietl, T.
Plesiewicz, W.
Lenard, A.
Skośkiewicz, T.
Kamińska, E.
Piotrowska, A.
Papis, E.
Frank, N.
Bauer, G.
Powiązania:
https://bibliotekanauki.pl/articles/1877113.pdf
Data publikacji:
1995-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Jv
Opis:
Magnetoresistance measurements of photolithographically patterned PbSe and Pb$\text{}_{1-y}$Mn$\text{}_{x}$Se microstructures were performed. Reproducible magnetoconductance fluctuations with the amplitude increasing with decreasing temperature were observed. Unexpectedly, these fluctuations contain a component periodic in the magnetic field, and their magnitude is greater than that expected from the current theory of the universal conductance fluctuations. Possible explanations are discussed.
Źródło:
Acta Physica Polonica A; 1995, 87, 2; 551-554
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron Localization in Sb-Doped Si/SiGe Superlattices
Autorzy:
Dietl, T.
Jaroszyński, J.
Sawicki, M.
Głód, P.
Wróbel, J.
Stöger, G.
Brunthaler, G.
Bauer, G.
Schäffler, F.
Powiązania:
https://bibliotekanauki.pl/articles/1933732.pdf
Data publikacji:
1995-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.61.Cw
72.15.Rn
73.20.Fz
Opis:
Millikelvin studies of in-plane magnetoconductance in short period Si/Ge:Sb superlattices have been carried out in order to examine the effect of anisotropy on quantum localization. The field-induced metal-to-insulator transition has been observed, indicating the existence of extended states. This suggests that despite anisotropy as large as D $\text{}_{∥}$/D$\text{}_{⊥}$ ≈ 10$\text{}^{3}$ the system behaves as 3D in respect of localization by disorder.
Źródło:
Acta Physica Polonica A; 1995, 88, 4; 699-702
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Observation of Two-Dimensional Electron Gas in LPE-Grown GaInAs-InP Heterostructures
Autorzy:
Fronc, K.
Grabecki, G.
Wróbel, J.
Dietl, T.
Gajewska, M.
Powiązania:
https://bibliotekanauki.pl/articles/1891365.pdf
Data publikacji:
1991-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.55.Df
73.20.Dx
73.60.Br
Opis:
A series of GaInAs/InP heterostructures was grown by liquid phase epitaxy. The heterostructures were characterized by magnetotransport measurements carried out down to 1.8 K and up 10 T. The results demonstrate the existence of the high-mobility two-dimensional electron gas in the narrow-gap GaInAs as well as the presence of residual conductance through the InP buffer layer.
Źródło:
Acta Physica Polonica A; 1991, 80, 3; 449-452
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Quantum Hall Ferromagnet in Magnetically-Doped Quantum Wells
Autorzy:
Andrearczyk, T.
Jaroszyński, J.
Wróbel, J.
Karczewski, G.
Wojtowicz, T.
Papis, E.
Kamińska, E.
Piotrowska, A.
Popović, D.
Dietl, T.
Powiązania:
https://bibliotekanauki.pl/articles/2036881.pdf
Data publikacji:
2003-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.43.Nq
72.25.Dc
73.61.Ga
75.50.Pp
Opis:
The article reviews our recent studies on quantum Hall ferromagnetism in diluted magnetic semiconductors. We carried out magnetoresistance studies on modulation-doped, gated heterostructures of (Cd,Mn)Te/(Cd,Mg)Te:I. We put into evidence the formation of Ising quantum Hall ferromagnet with Curie temperature T$\text{}_{C}$ as high as 2 K. Quantum Hall ferromagnetism is manifested by anomalous magnetoresistance maxima. Moreover, magnitude of these spikes depends dramatically on the history of the sample, shows hysteresis when either magnetic field or gate voltage are swept, stretched-exponential time evolution characteristic of glassy systems, and strong Barkhausen noise. Our study suggests that these metastabilities stem from the slow dynamics of ferromagnetic domains.
Źródło:
Acta Physica Polonica A; 2003, 104, 2; 93-102
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Conductance Fluctuations in Quantum Wires of n-CdTe and n-Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te
Autorzy:
Jaroszyński, J.
Wróbel, J.
Sawicki, M.
Skośkiewicz, T.
Karczewski, G.
Wojtowicz, T.
Kossut, J.
Dietl, T.
Kamińska, E.
Papis, E.
Barcz, A.
Piotrowska, A.
Powiązania:
https://bibliotekanauki.pl/articles/1934061.pdf
Data publikacji:
1995-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.15.Rn
73.61.Ga
73.20.Fz
Opis:
We present millikelvin studies of magnetoconductance in submicron wires of In-doped n$\text{}^{+}$-CdTe and n$\text{}^{+}$-Cd$\text{}_{0.99}$Mn$\text{}_{0.01}$Te epilayers. Weak-field magnetoresistance which arises from quantum localization as well as universal conductance fluctuations have been observed. The exchange coupling to magnetic impurities is shown to decrease the correlation field of the fluctuations. This novel effect is interpreted by invoking a new driving mechanism of the magnetoconductance fluctuations - the redistribution of the electrons between energy levels of the system, induced by the giant s-d spin-splitting of the electronic states.
Źródło:
Acta Physica Polonica A; 1995, 88, 5; 1000-1004
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Conductance Fluctuations in PbSe: Manifestation of Ballistic Transport in Macroscale?
Autorzy:
Grabecki, G.
Takeyama, S.
Adachi, S.
Takagi, Y.
Dietl, T.
Kamińska, E.
Piotrowska, A.
Papis, E.
Frank, N.
Bauer, G.
Powiązania:
https://bibliotekanauki.pl/articles/1933748.pdf
Data publikacji:
1995-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Jv
Opis:
Precise magnetoresistance measurements on microstructures of photolithographically patterned PbSe epilayers have been performed in the magnetic field range up to 17 Τ. Unusually large, reproducible magnetoconductance fluctuations have been observed. The fluctuation amplitude decreases exponentially with the magnetic field. A correlation magnetic field of the fluctuations corresponds to the Aharonov-Bohm effect which involves electron trajectories much smaller than the electron mean free path. This points strongly to the ballistic, not diffusive, origin of the observed phenomenon.
Źródło:
Acta Physica Polonica A; 1995, 88, 4; 727-730
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Conductance Fluctuations in Microstructures of HgCdMnTe Bicrystals
Autorzy:
Grabecki, G.
Lenard, A.
Plesiewicz, W.
Jaroszyński, J.
Cieplak, Marek
Skośkiewicz, T.
Dietl, T.
Kamińska, E.
Piotrowska, A.
Bulka, B.
Powiązania:
https://bibliotekanauki.pl/articles/1890700.pdf
Data publikacji:
1991-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.40.Lq
Opis:
Microscopic four-contact probes to semimagnetic HgCdMnTe grain-boundary inversion layers have been photolithographically patterned. Magnetoresistance measurements performed on these samples revealed aperiodic conductance fluctuations of the magnitude of the order of e$\text{}^{2}$/h. Quantitative analysis of both fluctuation amplitude and their mean period indicate that we have approached the mesoscopic regime in our system. This opens new possibilities in studies of spin-subsystem dynamics in semimagnetic semiconductors.
Źródło:
Acta Physica Polonica A; 1991, 80, 2; 307-310
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Characterization of Molecular Beam Epitaxy Grown $Cd_{1-x}$Mn$\text{}_{x}$Te Structures
Autorzy:
Sawicki, M.
Kolesnik, S.
Wojtowicz, T.
Karczewski, G.
Janik, E.
Kutrowski, M.
Żakrzewski, A.
Dynowska, E.
Dietl, T.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1931934.pdf
Data publikacji:
1995-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.-y
75.50.Rr
75.50.Ee
Opis:
The paper reports on the application of SQUID magnetometry to probe magnetic ion distribution in epilayers and at interfaces of diluted magnetic semiconductors. We present also new results on the possible influence of the magnetic confinement on the formation of the spin-glass phase, and on antiferromagnetic phase transition in zinc-blende MnTe.
Źródło:
Acta Physica Polonica A; 1995, 87, 1; 169-172
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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