Magnetic Ordering Of Eutepbte Multilayers Determined By X-ray Resonant Diffraction

In this work we use resonant x-ray diffraction combined with polarization analysis of the diffracted beam to study the magnetic ordering in EuTePbTe multilayers. The presence of satellites at the (1/2 1/2 1/2) magnetic reflection of a 50 repetition EuTePbTe superlattice demonstrated the existence of magnetic correlations among the alternated EuTe layers. The behavior of the satellites intensity as T increases toward the Ǹel temperature TN indicates that these correlations persist nearly up to TN and suggests the preferential decrease of the magnetic order parameter of external monolayers of each EuTe layer within the superlattice. © 2008 American Institute of Physics.9224Lovesey, S.W., Collins, S.P., (1996) X-Ray Scattering and Absorption by Magnetic Materials, , (Oxford University Press, New York)Granado, E., Pagliuso, P.G., Giles, C., Lora-Serrano, R., Yokaichiya, F., Sarrao, J.L., (2004) Phys. Rev. B, 69, p. 144411. , PRBMDO 0163-1829 10.1103/PhysRevB.69.144411Tonnerre, J.M., Seve, L., Raoux, D., Rodmacq, B., De Santis, M., Troussel, P., Brot, J.M., Chen, C.T., (1995) Nucl. Instrum. Methods Phys. Res. B, 97, p. 444. , NIMBEU 0168-583X 10.1016/0168-583X(94)00721-7Langridge, S., Stirling, W.G., Lander, G.H., Rebizant, J., (1994) Phys. Rev. B, 49, p. 12010. , PRBMDO 0163-1829 10.1103/PhysRevB.49.12010Leiner, V., Ay, M., Zabel, H., (2004) Phys. Rev. B, 70, p. 104429. , PRBMDO 0163-1829 10.1103/PhysRevB.70.104429Kepa, H., Springholz, G., Giebultowicz, T.M., Goldman, K.I., Majkrzak, C.F., Kacman, P., Blinowski, J., Bauer, G., (2003) Phys. Rev. B, 68, p. 024419. , PRBMDO 0163-1829 10.1103/PhysRevB.68.024419Binder, K., Hohenberg, P.C., (1974) Phys. Rev. B, 9, p. 2194. , PLRBAQ 0556-2805 10.1103/PhysRevB.9.2194Oliveira, N.F., Foner, S., Shapira, Y., Reed, T.B., (1972) Phys. Rev. B, 5, p. 2634. , PLRBAQ 0556-2805 10.1103/PhysRevB.5.2634Giles, C., Yokaichiya, F., Kycia, S.W., Sampaio, L.C., Ardiles-Saravia, D.C., Franco, M.K.K., Neuenschwander, R.T., (2003) J. Synchrotron Radiat., 10, p. 430. , JSYRES 0909-0495 10.1107/S0909049503020958Hol, V., Kubena, J., Ploog, K., (1990) Phys. Status Solidi B, 162, p. 347. , PSSBBD 0370-1972 10.1002/pssb.2221620204Nunez, V., Majkrzak, C.F., Springholz, G., Bauer, G., Giebultowicz, T.M., Kepa, H., Goldman, K.I., (1998) Superlattices Microstruct., 23, p. 41. , SUMIEK 0749-6036 10.1006/spmi.1996.0205Giebultowicz, T.M., Kepa, H., Blinowski, J., Kacman, P., (2001) Physica e (Amsterdam), 10, p. 411. , PELNFM 1386-9477 10.1016/S1386-9477(01)00128-

Structural And Magnetic Characterization Of Eute/snte Superlattices Grown By Molecular Beam Epitaxy

Here we investigate the structural and magnetic properties of 24 repetitions EuTe/SnTe superlattices (SLs), with 3 monolayers (ML) EuTe films and SnTe thicknesses between 13 and 36 ML. The SLs were grown by molecular beam epitaxy on 3 μm SnTe buffer layers, grown on top of (111)BaF2 substrates. High resolution x-ray diffraction measurements indicated that the SLs with thicker SnTe layers have higher structural quality. This is due to the SnTe growth mode on EuTe, which starts in islands and evolves to layer-by-layer. The magnetic diffraction peak observed for the higher quality SLs proved the existence of antiferromagnetic order within the individual EuTe layers. Decreasing the width of the non-magnetic SnTe layers resulted in rougher interfaces, and the fading of the magnetic peak signal. The magnetization versus applied field curves indicated that the magnetic moments of SLs with thinner SnTe layers were also harder to align along the field direction. We interpret our results considering the loss of Eu neighbors, related with the increasing roughness of the SL interfaces. © 2009 American Institute of Physics.1199157158Kepa, H., (2003) Phys. Rev. B, 68, p. 024419Blinowski, J., Kacman, P., (2001) Phys. Rev. B, 64, p. 045302Oliveira, N.F., Foner, S., Shapira, Y., Reed, T.B., (1972) Phys. Rev. B, 5, p. 2634Díaz, B., (2008) Appl. Phys. Lett, 92, p. 242511Díaz, B., Rappl, P.H.O., Abramof, E., (2007) J. Cryst. Growth, 308, p. 218Holý, V., Kubena, J., Ploog, K., (1990) Phys. Status Solidi B, 162, p. 347Giles, C., (2003) J. Synchrotron Rad, 10, p. 43

Coherent resonant tunneling in ac fields

We have analyzed the tunneling transmission probability and electronic current density through resonant heterostructures in the presence of an external electromagnetic field. In this work, we compare two different models for a double barrier : In the first case the effect of the external field is taken into account by spatially dependent AC voltages and in the second one the electromagnetic field is described in terms of a photon field that irradiates homogeneously the whole sample. While in the first description the tunneling takes place mainly through photo sidebands in the case of homogeneous illumination the main effective tunneling channels correspond to the coupling between different electronic states due to photon absorption and emission. The difference of tunneling mechanisms between these configurations is strongly reflected in the transmission and current density which present very different features in both cases. In order to analyze these effects we have obtained, within the Transfer Hamiltonian framework, a general expression for the transition probability for coherent resonant tunneling in terms of the Green's function of the system.Comment: 16 pages,Figures available upon request,to appear in Phys.Rev B (15 April 1996

Temperature-dependence of spin relaxation observed with high-field magnetooptics in GaAs/GaAlAs quantum-wells

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Systematic study of doping dependence on linear magnetoresistance in p-pbte

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Far infrared response of double barrier resonant tunneling structures

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Photon-assisted tunneling in sequential resonant tunneling devices

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Integer quantum Hall effect in a PbTe quantum well

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