Artículos de revistas
Gd 3+ And Eu 2+ Local Environment In Ca 1-xeu Xb 6 (0.0001 ≤ X ≤ 0.30) And Ca 1-xgd Xb 6 (0.0001 ≤ X ≤ 0.01)
Registro en:
Physica Status Solidi (a) Applications And Materials Science. , v. 203, n. 7, p. 1550 - 1555, 2006.
18626300
10.1002/pssa.200563125
2-s2.0-33745060779
Autor
Urbano R.R.
Pagliuso P.G.
Rettori C.
Schlottmann P.
Fisk Z.
Chapler B.
Oseroff S.B.
Institución
Resumen
Local environment of Gd 3+ and Eu 2+ 4f 7 ions, S =7/2, in Ca 1-xEu xB 6 (0.0001 ≤ x ≤ 0.30) and Ca xGd xB 6 (0.0001 ≤ x ≤ 0.01) is investigated by means of electron spin resonance (ESR). For x ≤ 0.001 the spectra show resolved fine structures due to the cubic crystal electric field and, in the case of Eu, the hyperfine structure due to the nuclear hyperfine field is also observed. The resonances have Lorentzian line shape, indicating insulating host for the Gd 3+ and Eu 2+ ions. As x increases, the ESR lines broaden due to local distortions caused by the Ca/Gd,Eu ions substitution. For Gd (x ≈ 0.001) and Eu (x ≈ 0.02), the spectra present superposition of Lorentzian and Dysonian resonances, suggesting a coexistence of insulating and metallic hosts for the Gd 3+ and Eu 2+ ions. The Gd 3+ and Eu 2+ fine structures are still observable up to x ≈ 0.003 for Gd and x ≈ 0.15 for Eu. For larger values of x the fine and hyperfine structures are no longer observed, the line width increases, and the line shape becomes pure Dysonian anticipating the metallic and semimetallic character of GdB 6 and EuB 6, respectively. These results clearly show that in the low concentration regime the Ca 1-xR xB 6 = Gd, Eu) systems are intrinsically inhomogeneous. No evidence of weak ferromagnetism (WF) was found in the ESR spectra of either metallic or insulating phases of these compounds, suggesting that, if WF is present in these materials, the Gd 3+ and Eu 2+ 4f 7 -electrons are shielded from the WF field. © 2006 WILEY-VCH Verlag GmbH & Co. KGaA. 203 7 1550 1555 Young, D.P., (1999) Nature, 397, p. 412 Zhitomirsky, M.E., (1999) Nature, 402, p. 251 Balents, L., Varma, C.M., (2000) Phys. Rev. Lett., 84, p. 1264 Barzykin, V., Gor'kov, L.P., (2000) Phys. Rev. Lett., 84, p. 2207 Jarlborg, T., (2001) Physica B, 307, p. 291 (2000) Phys. Rev. Lett., 85, p. 186 Ceperley, D., (1999) Nature, 397, p. 386 Tromp, H.J., (2000) Phys. Rev. Lett., 87, p. 16401 Massidda, S., Continenza, A., De Pascale, T.M., Monnier, R., (1997) Z. Phys. B, Condens. Matter, 102, p. 83 Urbano, R.R., Rettori, C., Barberis, G.E., Torelli, M., Bianchi, A., Fisk, Z., Pagliuso, P.G., Oseroff, S.B., (2002) Phys. Rev. B, 65, pp. 180407R Moriwaka, T., (2001) J. Phys. Soc. Jpn., 70, p. 341 Hall, D., (2001) Phys. Rev. B, 64, p. 233105 Vonlanthen, P., (2000) Phys. Rev. B, 62, p. 10076 Ott, H.R., (1997) Z. Phys. B, 102, p. 337 Gavilano, J.L., (2001) Phys. Rev. B, 63, pp. 140410R Giannio, K., (2002) J. Phys. Condens. Matter, 14, p. 1035 Denlinger, J.D., (2002) Phys. Rev. Lett., 89, p. 157601 Rhyee, J.-S., Cho, B.K., Ri, H.-C., (2003) Phys. Rev. B, 67, p. 125102 Souma, S., Komatsu, H., Takahashi, T., Kaji, R., Sasaki, T., Yokoo, Y., Akimitsu, J., (2003) Phys. Rev. Lett., 90, p. 027202 Terashima, T., (2000) J. Phys. Soc. Jpn., 69, p. 2423 Matsubayashi, K., Maki, M., Tsuzuki, T., (2002) Nature, 420, p. 143 Fisk, Z., (2002) Nature, 420, p. 144 Bennett, M.C., Van Lierop, J., Berkeley, E.M., Mansfield, J.F., Henderson, C., Aronson, M.C., Young, D.P., Lacerda, A., (2004) Phys. Rev. B, 69, p. 132407 Urbano, R.R., Pagliuso, P.G., Sarrao, J.L., Oseroff, S.B., Rettori, C., Bianchi, A., Nakatsuji, S., Fisk, Z., (2004) J. Magn. Magn. Mater., 272-276 (1 SUPPL.), pp. E1659 Urbano, R.R., Pagliuso, P.G., Rettori, C., Schlottmann, P., Sarrao, J.L., Bianchi, A., Nakatsuji, S., Oseroff, S.B., (2005) Phys. Rev. B, 71, p. 184422 Urbano, R.R., Pagliuso, P.G., Rettori, C., Oseroff, S.B., Sarrao, J.L., Schlottmann, P., Fisk, Z., (2004) Phys. Rev. B, 70, pp. 140401R Abragam, A., Bleaney, B., (1970) EPR of Transition Ions, , Clarendon Press, Oxford Pake, G.E., Purcell, E.M., (1948) Phys. Rev., 74, p. 1184 Bloembergen, N., (1952) J. Appl. Phys., 23, p. 1383 Feher, G., Kip, A.F., (1955) Phys. Rev., 98, p. 337 Dyson, F.J., (1955) Phys. Rev., 98, p. 349 Essam, J.W., (1972) Phase Transitions and Critical Phenomena, 2, p. 197. , edited by C. Domb and M. S. Green (Academic Press, London) Schlottmann, P., Hellberg, C.S., (1996) J. Appl. Phys., 79, p. 6414 Wigger, G.A., Beeli, C., Felder, E., Ott, H.R., Bianchi, A.D., Fisk, Z., (2004) Phys. Rev. Lett., 93, p. 147203