Electron-phonon induced spin relaxation in InAs quantum dots

We have calculated spin relaxation rates in parabolic quantum dots due to the phonon modulation of the spin-orbit interaction in presence of an external magnetic field. Both, deformation potential and piezoelectric electron-phonon coupling mechanisms are included within the Pavlov-Firsov spin-phonon Hamiltonian. Our results have demonstrated that, in narrow gap materials, the electron-phonon deformation potential and piezoelectric coupling give comparable contributions as spin relaxation processes. For large dots, the deformation potential interaction becomes dominant. This behavior is not observed in wide or intermediate gap semiconductors, where the piezoelectric coupling, in general, governs the spin relaxation processes. We also have demonstrated that spin relaxation rates are particularly sensitive to the Land\'e $g$-factor.Comment: 4 pages, 2 figures, to be appear in Physica E: Proceedings of the 11 International Conference on Narrow Gap Semiconductor

Electron Spin Resonance In Amorphous Silicon Doped With Gd

ESR experiments on Gd impurities in amorphous silicon between liquid-He and room temperatures show three resonances which could be ascribed to paramagnetic dangling bonds (g=2.00550.0005), to Gd S7/28 states (g=1.9970.005), and to a new paramagnetic center (g=2.100.05) associated with the presence of Gd atoms. For low-Gd-concentration samples the intensity of the resonance due to dangling bonds decreases as the Gd concentration increases and the intensity of the new paramagnetic center is found to increase with increasing temperature. These results indicate, as we recently found for other rare-earthelement impurities in a-Si, that a fraction of the Gd atoms act as acceptor impurities with associated loosely bound holes in the a-Si valence-band tail which are responsible for the resonance of the new paramagnetic center observed at a g value of 2.100.05. © 1989 The American Physical Society.39128398840

New Paramagnetic Center In Amorphous Silicon Doped With Rare-earth Elements

A new paramagnetic center associated with rare earths (RE) (La, Ce, Pr, Nd, Gd, Er, and Lu) in amorphous silicon is reported. It is shown that RE impurities are incorporated in a-Si and that the density of paramagnetic dangling bonds decreases as a consequence of the presence of these impurities. An interpretation in terms of RE 6s orbitals and crystal-field-split 5d orbital hybridization suggests that the RE behaves as an acceptor impurity with an associated hole in the a-Si valence-band tail, which is responsible for the observed resonance at a g value of 2.100.01. © 1989 The American Physical Society.3942860286

Spin injection in n-type resonant tunneling diodes

We have studied the polarized resolved photoluminescence of n-type GaAs/AlAs/GaAlAs resonant tunneling diodes under magnetic field parallel to the tunnel current. Under resonant tunneling conditions, we have observed two emission lines attributed to neutral (X) and negatively charged excitons (X− ). We have observed a voltage-controlled circular polarization degree from the quantum well emission for both lines, with values up to −88% at 15 T at low voltages which are ascribed to an efficient spin injection from the 2D gases formed at the accumulation layers

The Metabolic Benefits of Menopausal Hormone Therapy Are Not Mediated by Improved Nutritional Habits. The OsteoLaus Cohort.

Menopause alters body composition by increasing fat mass. Menopausal hormone therapy (MHT) is associated with decreased total and visceral adiposity. It is unclear whether MHT favorably affects energy intake. We aimed to assess in the OsteoLaus cohort whether total energy intake (TEI) and/or diet quality (macro- and micronutrients, dietary patterns, dietary scores, dietary recommendations)-evaluated by a validated food frequency questionnaire-differ in 839 postmenopausal women classified as current, past or never MHT users. There was no difference between groups regarding TEI or consumption of macronutrients. After multivariable adjustment, MHT users were less likely to adhere to the unhealthy pattern 'fat and sugar: Current vs. never users [OR (95% CI): 0.48 (0.28-0.82)]; past vs. never users [OR (95% CI): 0.47 (0.27-0.78)]. Past users exhibited a better performance in the revised score for Mediterranean diet than never users (5.00 ± 0.12 vs. 4.63 ± 0.08, p < 0.04). Differences regarding compliance with dietary recommendations were no longer significant after adjustment for covariates. Overall, these results argue against a major role of TEI and diet quality as possible mediators of the MHT metabolic benefits. Future research on this relationship should focus on other potential targets of MHT, such as resting energy expenditure and physical activity

Nanothermometer based on resonant tunneling diodes : from cryogenic to room temperatures

The authors are grateful for financial support by the BMBF via national project EIPHRIK (FKZ: 13N10710), the European Union (FPVII (2007-2013) under grant agreement No. 256959 NANOPOWER and No. 318287 LANDAUER), and the Brazilian Agencies FAPESP (2013/24253-5, 2012/13052-6, and 2012/51415-3), CNPq and CAPES.Sensor miniaturization together with broadening temperature sensing range are fundamental challenges in nanothermometry. By exploiting a large temperature-dependent screening effect observed in a resonant tunneling diode in sequence with a GaInNAs/GaAs quantum well, we present a low dimensional, wide range, and high sensitive nanothermometer. This sensor shows a large threshold voltage shift of the bistable switching of more than 4.5 V for a temperature raise from 4.5 to 295 K, with a linear voltage-temperature response of 19.2 mV K-1, and a temperature uncertainty in the millikelvin (mK) range. Also, when we monitor the electroluminescence emission spectrum, an optical read-out control of the thermometer is provided. The combination of electrical and optical read-outs together with the sensor architecture excel the device as a thermometer with the capability of noninvasive temperature sensing, high local resolution, and sensitivity.PostprintPeer reviewe

Exciton G Factor Of Type-ii Inp Gaas Single Quantum Dots

We investigated the magneto-optical properties of type-II InP GaAs quantum dots using single-dot spectroscopy. The emission energy from individual dots presents a quadratic diamagnetic shift and a linear Zeeman splitting as a function of magnetic fields up to 10 T, as previously observed for type-I systems. We analyzed the in-plane localization of the carriers using the diamagnetic shift results. The values for the exciton g factor obtained for a large number of a InP GaAs dots are mainly constant, independent of the emission energy, and therefore, of the quantum dot dimensions. The result is attributed to the weak confinement of the holes in type-II InP GaAs quantum dots. © 2006 The American Physical Society.733Toda, Y., Shinomori, S., Suzuki, K., Arakawa, Y., (1998) Appl. Phys. Lett., 73, p. 517. , APPLAB 0003-6951 10.1063/1.121919Bayer, M., Kuther, A., Schäfer, F., Reithmaier, J.P., Forchel, A., (1999) Phys. Rev. B, 60, p. 8481. , PRBMDO. 0163-1829. 10.1103/PhysRevB.60.R8481Sugisaki, M., Ren, H.-W., Nishi, K., Sugou, S., Okuno, T., Masumoto, Y., (1998) Physica B, 256-258, p. 169. , PHYBE3 0921-4526Kotlyar, R., Reinecke, T.L., Bayer, M., Forchel, A., (2001) Phys. Rev. B, 63, p. 085310. , PRBMDO 0163-1829 10.1103/PhysRevB.63.085310Ribeiro, E., Govorov, A.O., Carvalho Jr., W., Medeiros-Ribeiro, G., (2004) Phys. Rev. Lett., 92, p. 126402. , PRLTAO 0031-9007 10.1103/PhysRevLett.92.126402Janssens, K.L., Partoens, B., Peeters, F.M., (2002) Phys. Rev. B, 66, p. 075314. , PRBMDO 0163-1829 10.1103/PhysRevB.66.075314Kalameitsev, A.B., Kovalev, V.M., Govorov, A.O., (1989) JETP Lett., 68, p. 669. , JTPLA2 0021-3640 10.1134/1.567926Sugisaki, M., Ren, H.W., Nair, S.V., Nishi, K., Masumoto, Y., (2002) Phys. Rev. B, 66, p. 235309. , PRBMDO 0163-1829 10.1103/PhysRevB.66.235309Godoy, M.P.F., Nakaema, M.K.K., Iikawa, F., Carvalho Jr., W., Ribeiro, E., Gobby, A.L., (2004) Rev. Sci. Instrum., 75, p. 1947. , RSINAK 0034-6748 10.1063/1.1753090Walck, S.N., Reinecke, T.L., (1998) Phys. Rev. B, 57, p. 9088. , PRBMDO 0163-1829 10.1103/PhysRevB.57.9088Laheld, U.E.H., Pedersen, F.B., Hemmer, P.C., (1993) Phys. Rev. B, 48, p. 4659. , PRBMDO 0163-1829 10.1103/PhysRevB.48.4659Bastard, G., Mendez, E.E., Chang, L.L., Esaki, L., (1982) Phys. Rev. B, 26, p. 1974. , PRBMDO 0163-1829 10.1103/PhysRevB.26.1974Nakaoka, T., Saito, T., Tatebayashi, J., Arakawa, Y., (2004) Phys. Rev. B, 70, p. 235337. , PRBMDO 0163-1829 10.1103/PhysRevB.70.235337Yugova, I.A., Ya. Gerlovin, I., Davydov, V.G., Ignatiev, I.V., Kozin, I.E., Ren, H.W., Sugisaki, M., Masumoto, Y., (2002) Phys. Rev. B, 66, p. 235309. , PRBMDO 0163-1829 10.1103/PhysRevB.66.235309Willmann, F., Suga, S., Dreybrodt, W., Cho, K., (1974) Solid State Commun., 14, p. 783. , SSCOA4 0038-1098Landi, S.M., Tribuzy, C.V.B., Souza, P.L., Butendeich, R., Bittencourt, A.C., Marques, G.E., (2003) Phys. Rev. B, 67, p. 085304. , PRBMDO 0163-1829 10.1103/PhysRevB.67.08530

Light Controlled Spin Polarization In Asymmetric N -type Resonant Tunneling Diode

The authors have observed a strong dependence of the circular polarization degree from the quantum well emission in an asymmetric n -type GaAsAlAsAlGaAs resonant tunneling diode on both the laser excitation intensity and the applied bias voltage. The sign of the circular polarization can be reversed by increasing the light excitation intensity when the structure is biased with voltages slightly larger than the first electron resonance. The variation of polarization is associated with a large density of photogenerated holes accumulated in the quantum well, which is enhanced due to the asymmetry of the structure. © 2007 American Institute of Physics.917Hanbicki, A., Van Erve, O.M.J., Magno, R., Kioseoglou, G., Li, C.H., Jonker, B.T., Itskos, G., Petrou, A., (2003) Appl. Phys. Lett., 82, p. 4092Jiang, X., Wang, R., Shelby, R.M., MacFarlane, R.M., Bank, S.R., Harris, J.S., Parkin, S.S.P., (2005) Phys. Rev. Lett., 94, p. 056601Motsnyi, V.F., Van Dorpe, P., Van Roy, W., Goovaerts, E., Safarov, V.I., Borghs, G., De Boeck, J., (2003) Phys. Rev. B, 68, p. 245319Fiederling, R., Keim, M., Reuscher, G., Ossau, W., Schmidt, G., Waag, A., Molenkamp, L.W., (1999) Nature (London), 402, p. 787Ohno, Y., Young, D.K., Beschoten, B., Matsukura, F., Ohno, H., Awschalom, D., (1999) Nature (London), 402, p. 790Oestreich, M.J., Hübner, M.J., Hägele, D., Klar, P.J., Heimbrodt, W., Rühle, W.W., Ashenford, D.E., Lunn, B., (1999) Appl. Phys. Lett., 74, p. 1251Jonker, B.T., Park, Y.D., Bennett, B.R., Cheong, H.D., Kioseoglou, G., Petrou, A., (2000) Phys. Rev. B, 62, p. 8180Braden, J.G., Parker, J.S., Xiong, P., Chun, S.H., Samarth, N., (2003) Phys. Rev. Lett., 91, p. 056602Mattana, R., George, J.-M., Jaffr̀s, H., Nguyen Van Dau, F., Fert, A., Ĺpine, B., Guivarc'H, A., J́źquel, G., (2003) Phys. Rev. Lett., 90, p. 166601Gruber, Th., Keim, M., Fiederling, R., Reuscher, G., Ossau, W., Schmidt, G., Molenkamp, M., Waag, A., (2001) Appl. Phys. Lett., 78, p. 1101Slobodskyy, A., Gould, C., Slobodskyy, T., Becker, C.R., Schmidt, G., Molenkamp, L.W., (2003) Phys. Rev. Lett., 90, p. 246601De Carvalho, H.B., Galvão Gobato, Y., Brasil, M.J.S.P., Lopez-Richard, V., Marques, G.E., Camps, I., Henini, M., Hill, G., (2006) Phys. Rev. B, 73, p. 155317De Carvalho, H.B., Brasil, M.J.S.P., Galvão Gobato, Y., Marques, G.E., Galeti, H.V.A., Henini, M., Hill, G., (2007) Appl. Phys. Lett., 90, p. 62120Buhmann, H., Mansouri, L., Wang, J., Beton, P.H., Mori, N., Eaves, L., Henini, M., Potemski, M., (1995) Phys. Rev. B, 51, p. 7969Teran, F.J., Eaves, L., Mansouri, L., Buhmann, H., Maude, D.K., Potemski, M., Henini, M., Hill, G., (2005) Phys. Rev. B, 71, p. 161309Glasberg, S., Finkelstein, G., Shtrikman, H., Bar-Joseph, I., (1999) Phys. Rev. B, 59, p. 10425Vanhoucke, T., Hayne, M., Henini, M., Moshchalkov, V.V., (2002) Phys. Rev. B, 65, p. 041307Marie, X., Amand, T., Le Jeune, P., Paillard, M., Renucci, P., Golub, L.E., Dymnikov, V.D., Ivchenko, E.L., (1999) Phys. Rev. B, 60, p. 5811Van Kesteren, H.W., Cosman, E.C., Van Der Poel, W.A.J.A., Foxon, C.T., (1990) Phys. Rev. B, 41, p. 528

Menopausal Hormone Therapy Is Associated With Reduced Total and Visceral Adiposity: The OsteoLaus Cohort.

After menopause, fat mass (FM) and visceral adipose tissue (VAT) increase and nonbone lean body mass (LBM) decreases. Whether menopausal hormone therapy (MHT) reverses these changes remains controversial. To assess the effect of MHT on FM, VAT, and LBM before and after its withdrawal and evaluate potential confounders. Cross-sectional study. General community. Women of the OsteoLaus cohort (50 to 80 years old) who underwent dual-energy X-ray absorptiometry (DXA) with body composition assessment. After we excluded women with estrogen-modifying medications, the 1053 participants were categorized into current users (CUs), past users (PUs), and never users (NUs) of MHT. None. VAT measured by DXA was the primary outcome. We assessed subtotal and android FM, LBM, muscle strength (hand grip), and confounding factors (caloric intake, physical activity, biomarkers). The groups significantly differed in age, NU < CU < PU. Age-adjusted VAT was lower in CUs than NUs (P = 0.03). CUs exhibited lower age-adjusted body mass index (BMI) (-0.9 kg/m2) and a trend for lower FM (-1.3 kg). The 10-year gain of VAT (P < 0.01) and subtotal and android FM (P < 0.05) was prevented in CUs. No difference in LBM or hand grip was detected. No residual effect was detected for PUs, including for early MHT discontinuers. The confounding factors did not significantly differ between groups except for higher caloric intake in PUs compared with NUs. MHT is associated with significantly decreased VAT, BMI, and android FM. No benefit is detected for LBM. The benefits are not preserved in PUs, suggesting caution when MHT is discontinued

Polarization Resolved Luminescence In Asymmetric N -type Gaasalgaas Resonant Tunneling Diodes

We have investigated the polarized emission from a n -type GaAsAlGaAs resonant tunneling diode under magnetic field. The GaAs contact layer emission shows a large constant negative circular polarization. A similar result is observed for the quantum well, but only when electrons are injected from the substrate, while for inverted biases, the polarization tends to become positive for small voltages and large laser excitation intensities. We believe that the quantum well polarization may be associated to the partial thermalization of minority carriers on the well subbands and is thus critically dependent on the bias-controlled density of carriers accumulated in the well. © 2008 American Institute of Physics.9214Hanbicki, A., Van Erve, O.M.J., Magno, R., Kioseoglou, G., Li, C.H., Jonker, B.T., Itskos, G., Petrou, A., (2003) Appl. Phys. Lett., 82, p. 4092Jiang, X., Wang, R., Shelby, R.M., MacFarlane, R.M., Bank, S.R., Harris, J.S., Parkin, S.S.P., (2005) Phys. Rev. Lett., 94, p. 056601Motsnyi, V.F., Van Dorpe, P., Van Roy, W., Goovaerts, E., Safarov, V.I., Borghs, G., De Boeck, J., (2003) Phys. Rev. B, 68, p. 245319Fiederling, R., Keim, M., Reuscher, G., Ossau, W., Schmidt, G., Waag, A., Molenkamp, L.W., (1999) Nature (London), 402, p. 787Ohno, Y., Young, D.K., Beschoten, B., Matsukura, F., Ohno, H., Awschalom, D., (1999) Nature (London), 402, p. 790Oestreich, M.J., Hübner, M.J., Hägele, D., Klar, P.J., Heimbrodt, W., Rühle, W.W., Ashenford, D.E., Lunn, B., (1999) Appl. Phys. Lett., 74, p. 1251Jonker, B.T., Park, Y.D., Bennett, B.R., Cheong, H.D., Kioseoglou, G., Petrou, A., (2000) Phys. Rev. B, 62, p. 8180Braden, J.G., Parker, J.S., Xiong, P., Chun, S.H., Samarth, N., (2003) Phys. Rev. Lett., 91, p. 056602Mattana, R., George, J.-M., Jaffr̀s, H., Nguyen Van Dau, F., Fert, A., Ĺpine, B., Guivarc'H, A., J́źquel, G., (2003) Phys. Rev. Lett., 90, p. 166601Gruber, T., Keim, M., Fiederling, R., Reuscher, G., Ossau, W., Schmidt, G., Molenkamp, M., Waag, A., (2001) Appl. Phys. Lett., 78, p. 1101Slobodskyy, A., Gould, C., Slobodskyy, T., Becker, C.R., Schmidt, G., Molenkamp, L.W., (2003) Phys. Rev. Lett., 90, p. 246601De Carvalho, H.B., Galvão Gobato, Y., Brasil, M.J.S.P., Lopez-Richard, V., Marques, G.E., Camps, I., Henini, M., Hill, G., (2006) Phys. Rev. B, 73, p. 155317De Carvalho, H.B., Brasil, M.J.S.P., Galvão Gobato, Y., Marques, G.E., Galeti, H.V.A., Henini, M., Hill, G., (2007) Appl. Phys. Lett., 90, p. 062120Dos Santos, L.F., Galvão Gobato, Y., Marques, G.E., Brasil, M.J.S.P., Henini, M., Airey, R., (2007) Appl. Phys. Lett., 91, p. 073520Snelling, M.J., Blackwood, E., MacDonagh, C.J., Harley, R.T., Foxon, C.T.B., (1992) Phys. Rev. B, 45, p. 392