Esr In A Heavy-fermion Alloy (ube13) Doped With Local Moments

We have determined the ESR properties of UBe13 doped with dilute local moments of Er, Dy, or Gd over the temperature region where there is a large variation in the enhanced specific heat. We find that neither the enhancement, the temperature variation, nor any other anomalous behavior appears to be mirrored in the ESR data. We suggest that this unexpected result must be incorporated into current models of heavy-fermion systems. © 1985 The American Physical Society.55242719272

Electron Spin Resonance Of Gd3+ In Gdm Mn In3m+2n (m=rh,ir; N=0,1; M=1,2) Antiferromagnets

We report electron spin resonance experiments of Gd3+ in the Gdm Mn In3m+2n (M=Rh,Ir; n=0,1; m=1,2) intermetallic compounds. For T TN ∼45 K, all compounds present a single Dysonian resonance and show a Korringa-like temperature dependence of the linewidth, ΔH=a+bT. The residual linewidth a is strongly affected by the transition metal M=Rh or Ir and/or by the layering (m=1 or 2) or change in structure (n=0,1). The residual linewidth is associated with an unresolved crystalline electrical field (CEF) fine structure. Consequently, a systematic evolution of the CEF in the Gdm Mn In3m+2n compounds is inferred. A discussion to what extent our results can explain to the CEF effects observed in isostructural R-based compounds will be given. © 2008 American Institute of Physics.1037Hegger, H., (2000) Phys. Rev. Lett., 84, p. 4986Petrovic, C., (2001) Europhys. Lett., 53, p. 354Petrovic, C., (2001) J. Phys.: Condens. Matter, 13, p. 337Pagliuso, P.G., (2001) Phys. Rev. B, 63, p. 054426Pagliuso, P.G., (2000) Phys. Rev. B, 62, p. 12266Thompson, J.D., (2001) J. Magn. Magn. Mater., 226-230, p. 5Pagliuso, P.G., (2001) Phys. Rev. B, 64, p. 100503. , (R)Sidorov, V.A., (2002) Phys. Rev. Lett., 89, p. 157004Bianchi, A., (2003) Phys. Rev. Lett., 91, p. 257001Park, T., (2006) Nature (London), 440, p. 65Pham, L.D., (2006) Phys. Rev. Lett., 97, p. 056404Hering, E.N., (2006) Physica B, 378-380, p. 423Pagliuso, P.G., (2006) J. Appl. Phys., 99, pp. 08P703Granado, E., (2006) Phys. Rev. B, 74, p. 214428Granado, E., (2004) Phys. Rev. B, 69, p. 144411Lora-Serrano, R., (2006) Phys. Rev. B, 74, p. 214404Lora-Serrano, R., (2006) Physica B, 384, p. 326Amara, M., Amara, M., Amara, M., (1994) J. Magn. Magn. Mater., 130, p. 127. , 0304-8853 10.1016/0304-8853(94)90665-3, ();, J. Magn. Magn. Mater. 0304-8853 10.1016/0304-8853(94)90284-4 131, 402 (1994);, J. Magn. Magn. Mater. 140-144, 1157 (1994)Czopnik, A., (1991) Phys. Status Solidi A, 127, p. 243Abragam, Bleaney, B., (1670), Electron Paramagnetic Resonance of Transition Ions (Clarendon, Oxford)Korringa, J., (1950) Physica (Amsterdam), 10, p. 601Rettori, C., (1974) Phys. Rev. B, 10, p. 1826Davidov, D., (1973) Solid State Commun., 12, p. 62

Evolution From Insulator (x=0.003) To Metal (x=1) Of The Eu 2+ Local Environment In Ca 1-xeu Xb 6

The local environment of Eu2+ (4 f7, S=72) in Ca1-x Eux B6 (0.003≤x≤1.00) is studied by means of electron spin resonance (ESR). For x≲0.07 the resonances have Lorentzian line shape, indicating an insulating environment for the Eu2+ ions. For x≳0.07, the lines broaden and become Dysonian in shape, suggesting a change to metallic environment for the Eu2+ ions, anticipating the semimetallic character of EuB6. The broadening is attributed to a spin-flip scattering relaxation process due to the exchange interaction between conduction and Eu2+ 4f electrons. High field ESR measurements for x≳0.30 reveal narrower and anisotropic linewidths, which are attributed to magnetic polarons and Fermi surface effects, respectively. © 2005 American Institute of Physics.9710Young, D.P., (1999) Nature (London), 397, p. 412Zhitomirsky, M.E., (1999) Nature (London), 402, p. 251Tromp, H.J., (2000) Phys. Rev. Lett., 87, p. 016401Massidda, S., Continenza, A., De Pascale, T.M., Monnier, R., (1997) Z. Phys. B: Condens. Matter, 102, p. 83Urbano, R.R., (2002) Phys. Rev. B, 65, p. 180407Bennett, M.C., (2004) Phys. Rev. B, 69, p. 132407Urbano, R.R., Pagliuso, P.G., Rettori, C., Oseroff, S.B., Sarrao, J.L., Schlottmann, P., Fisk, Z., (2004) Phys. Rev. B, 70, p. 140401Pake, G.E., Purcell, E.M., (1948) Phys. Rev., 74, p. 1184Bloembergen, N., (1952) J. Appl. Phys., 23, p. 1383Feher, G., Kip, A.F., (1955) Phys. Rev., 98, p. 337Dyson, F.J., (1955) Phys. Rev., 98, p. 349Sperlich, G., Jansen, K., (1974) Solid State Commun., 15, p. 1105Essam, J.W., (1972) Phase Transitions and Critical Phenomena, 2, p. 197. , Academic, LondonSchlottmann, P., Hellberg, C.S., (1996) J. Appl. Phys., 79, p. 6414Fisk, Z., (1979) J. Appl. Phys., 50, p. 1911Goodrich, R.G., Harrison, N., Vuillemin, J.J., Tekul, A., Hall, D.W., Fisk, Z., Young, D., Sarrao, J., (1998) Phys. Rev. B, 58, p. 14896Rhyee, J.-S., Cho, B.K., Ri, H.-C., (2003) Phys. Rev. B, 67, p. 125102Wigger, G.A., Beeli, C., Felder, E., Ott, H.R., Bianchi, A.D., Fisk, Z., (2004) Phys. Rev. Lett., 93, p. 14720

Quantum Critical Kondo Quasiparticles Probed By Esr In β-ybalb 4

Electron spin resonance (ESR) can probe conduction electrons (CE) and local moment (LM) spin systems in different materials. A CE spin resonance (CESR) is observed in metallic systems based on light elements or with enhanced Pauli susceptibility. LM ESR can be seen in compounds with paramagnetic ions and localized d or f electrons. Here we report a remarkable and unprecedented ESR signal in the heavy-fermion superconductor β-YbAlB4 which behaves as a CESR at high temperatures and acquires characteristics of the Yb3 LM ESR at low temperature. This dual behavior strikes as an in situ unique observation of the Kondo quasiparticles in a quantum critical regime. The proximity to a quantum critical point may favor the appearance of this dual character of the ESR signal in β-YbAlB4. © 2011 American Physical Society.1072Tien, C., Yu, J., Duh, H., (1993) Jpn. J. Appl. Phys., 32, p. 2658. , JAPNDE 0021-4922 10.1143/JJAP.32.2658Sichelschmidt, J., (2003) Phys. Rev. Lett., 91, p. 156401. , PRLTAO 0031-9007 10.1103/PhysRevLett.91.156401Sichelschmidt, J., (2007) J. Phys. Condens. Matter, 19, p. 016211. , JCOMEL 0953-8984 10.1088/0953-8984/19/1/016211Krellner, C., Forster, T., Jeevan, H., Geibel, C., Sichelschmidt, J., Relevance of ferromagnetic correlations for the electron spin resonance in kondo lattice systems (2008) Physical Review Letters, 100 (6), p. 066401. , http://oai.aps.org/oai?verb=GetRecord&Identifier=oai:aps.org: PhysRevLett.100.066401&metadataPrefix=oai_apsmeta_2, DOI 10.1103/PhysRevLett.100.066401Abrahams, E., Wolfle, P., (2008) Phys. Rev. B, 78, p. 104423. , PRBMDO 1098-0121 10.1103/PhysRevB.78.104423Schlottmann, P., (2009) Phys. Rev. B, 79, p. 045104. , PRBMDO 1098-0121 10.1103/PhysRevB.79.045104Macaluso, R.T., Nakatsuji, S., Kuga, K., Thomas, E.L., Machida, Y., Maeno, Y., Fisk, Z., Chan, J.Y., Crystal structure and physical properties of polymorphs of LnAlB 4 (Ln = Yb, Lu) (2007) Chemistry of Materials, 19 (8), pp. 1918-1922. , DOI 10.1021/cm062244+Nakatsuji, S., (2008) Nature Phys., 4, p. 603. , NPAHAX 1745-2473 10.1038/nphys1002Duque, J.G.S., (2009) Phys. Rev. B, 79, p. 035122. , PRBMDO 1098-0121 10.1103/PhysRevB.79.035122Trovarelli, O., (2000) Phys. Rev. Lett., 85, p. 626. , PRLTAO 0031-9007 10.1103/PhysRevLett.85.626Gegenwart, P., (2002) Phys. Rev. Lett., 89, p. 056402. , PRLTAO 0031-9007 10.1103/PhysRevLett.89.056402Dyson, F.J., (1955) Phys. Rev., 98, p. 349. , PHRVAO 0031-899X 10.1103/PhysRev.98.349Tao, L.J., (1971) Phys. Rev. B, 4, p. 5. , PRBMDO 0556-2805 10.1103/PhysRevB.4.5Abragam, A., Bleaney, B., (1970) EPR of Transitions Ions, , Clarendon, OxfordSattler, J.P., Nemarich, J., (1970) Phys. Rev. B, 1, p. 4249. , PRBMDO 0556-2805 10.1103/PhysRevB.1.4249Rettori, C., (1981) Physica (Amsterdam), 107, p. 359. , PHYBE3 0378-4363 10.1016/0378-4363(81)90485-XHuber, D.L., (2004) Phys. Rev. B, 70, p. 125417. , PRBMDO 1098-0121 10.1103/PhysRevB.70.125417Oseroff, S.B., (1977) Phys. Rev. B, 15, p. 1283. , PRBMDO 0556-2805 10.1103/PhysRevB.15.1283Continetino, M., (2005) Braz. J. Phys., 35, p. 197. , BJPHE6 0103-9733 10.1590/S0103-97332005000100018Coleman, P., Pepin, C., Si, Q., Ramazashvili, R., How do Fermi liquids get heavy and die? (2001) Journal of Physics Condensed Matter, 13 (35), pp. R723-R738. , DOI 10.1088/0953-8984/13/35/202, PII S095389840124853XMonod, P., (1978) J. Phys. (Paris), 39, pp. 6-1472. , JOPQAG 0302-0738 10.1051/jphyscol:19786589Rettori, C., (1997) Phys. Rev. B, 55, p. 1016. , PRBMDO 0163-1829 10.1103/PhysRevB.55.1016Pagliuso, P.G., (1997) Phys. Rev. B, 56, p. 8933. , PRBMDO 0163-1829 10.1103/PhysRevB.56.8933Urbano, R.R., (2002) Phys. Rev. Lett., 89, p. 087602. , PRLTAO 0031-9007 10.1103/PhysRevLett.89.087602Likodimos, V., Koutandos, S., Pissas, M., Papavassiliou, G., Prassides, K., Conduction electron spin resonance in Mg1-xAl xB2 (2003) Europhysics Letters, 61 (1), pp. 116-121. , DOI 10.1209/epl/i2003-00257-1Sercheli, M.S., Kopelevich, Y., Ricardo Da Silva, R., Torres, J.H.S., Rettori, C., Evidence for internal field in graphite: A conduction electron spin-resonance study (2002) Solid State Communications, 121 (9-10), pp. 579-583. , DOI 10.1016/S0038-1098(01)00465-3, PII S0038109801004653Walmsley, L., Rettori, C., C-Axis resistivity in graphite-AlCl3 as found by CESR measurements (1990) Synthetic Metals, 36 (2), pp. 235-239. , DOI 10.1016/0379-6779(90)90056-QPfluger, P., (1983) Synth. Met., 8, p. 15. , SYMEDZ 0379-6779 10.1016/0379-6779(83)90004-8Nevidomskyy, A.H., Coleman, P., (2009) Phys. Rev. Lett., 102, p. 077202. , PRLTAO 0031-9007 10.1103/PhysRevLett.102.077202Si, Q., Rabello, S., Ingersent, K., Smith, J.L., Locally critical quantum phase transitions in strongly correlated metals (2001) Nature, 413 (6858), pp. 804-808. , DOI 10.1038/3510150

Noncubic Symmetry In Ca 1-xeu Xb 6 (0.15≲x≤1.00): An Electron-spin-resonance Study

The Eu2+ (4 f7, S=72) g value in Ca1-x Eux B6 (0.15≲x≤1.00) was measured by means of electron spin resonance at two frequencies (fields), 9.4 (≈3.4 kOe) and 34.4 GHz (≈12.1 kOe). The g value was found to be anisotropic and magnetic-field dependent. The amplitude of the anisotropy increases at low temperatures. The observed angular and temperature dependences of the g value suggest tetragonal symmetry caused, presumably, by a distortion along a direction perpendicular to the largest crystal face, the [001] direction. Due to the platelet shape of the samples, part of the anisotropy of the g value can also be attributed to demagnetization effects. The g values decrease at higher fields, which is interpreted in terms of a two-band model involving an exchange interaction between the localized Eu2+ 4 f7 electrons with conduction Eu2+ 5d -like electrons and B 2p -like holes. © 2006 American Institute of Physics.998Etourneau, J., Hagenmuller, P., (1985) Philos. Mag. B, 52, p. 589Young, D.P., (1999) Nature (London), 397, p. 412Zhitomirsky, M.E., Rice, T.M., Anisimov, V.I., (1999) Nature (London), 402, p. 251Degiorgi, L., Felder, E., Ott, H.R., Sarrao, J.L., Fisk, Z., (1997) Phys. Rev. Lett., 79, p. 5134Massidda, S., Continenza, A., De Pascale, T.M., Monnier, R., (1997) Z. Phys. B: Condens. Matter, 102, p. 83Süllow, S., (1998) Phys. Rev. B, 57, p. 5860Booth, C.H., Sarrao, J.L., Hundley, M.F., Cornelius, A.L., Kwei, G.H., Bianchi, A., Fisk, Z., Lawrence, J.M., (2001) Phys. Rev. B, 63, p. 224302Paschen, S., Pushim, D., Schlatter, M., Vonlanthen, P., Ott, H.R., Young, D.P., Fisk, Z., (2000) Phys. Rev. B, 61, p. 4174Wigger, G.A., Walti, Ch., Ott, H.R., Bianchi, A.D., Fisk, Z., (2002) Phys. Rev. B, 66, p. 212410Wigger, G.A., Beeli, C., Felder, E., Ott, H.R., Bianchi, A.D., Fisk, Z., (2004) Phys. Rev. Lett., 93, p. 147203Uimin, G., (1997) Phys. Rev. B, 55, p. 8267Sturm, H., Elschner, B., Hock, K.-H., (1985) Phys. Rev. Lett., 54, p. 1291Altshuler, T.S., Bresler, M.S., (1999) J. Exp. Theor. Phys., 88, p. 1019Süllow, S., Prasad, I., Aronson, M.C., Bogdanovich, S., Sarrao, J.L., Fisk, Z., (2000) Phys. Rev. B, 62, p. 11626Urbano, R.R., Pagliuso, P.G., Rettori, C., Oseroff, S.B., Sarrao, J.L., Schlottmann, P., Fisk, Z., (2004) Phys. Rev. B, 70, p. 140401Urbano, R.R., (2005) Phys. Rev. B, 71, p. 184422Feher, G., Kip, A.F., (1955) Phys. Rev., 98, p. 337. , 0031-899X 10.1103/PhysRev.98.337Dyson, F.J., (1955) Phys. Rev., 98, p. 349. , 0031-899X 10.1103/PhysRev.98.349Pake, G.E., Purcell, E.M., (1948) Phys. Rev., 74, p. 1184Abragam, A., Bleaney, B., (1970) EPR of Transition Ions, , Clarendon, OxfordKunii, S., Uemura, T., Chiba, Y., Kasuya, T., Date, M., (1985) J. Magn. Magn. Mater., 52, p. 271. , 0304-8853 10.1016/0304-8853(85)90277-XKunii, S., (2000) J. Phys. Soc. Jpn., 69, p. 3789Bisch, P.M., Troper, A., Gomes, A.A., (1976) Phys. Rev. B, 13, p. 3902. , 0556-2805 10.1103/PhysRevB.13.3902Troper, A., De Menezes, O.L.T., Lederer, P., Gomes, A.A., (1978) Phys. Rev. B, 18, p. 3709. , 0556-2805 10.1103/PhysRevB.18.3709Barberis, G.E., Davidov, D., Donoso, J.P., Rettori, C., Suassuna, J.F., Dokter, H.D., (1979) Phys. Rev. B, 19, p. 5495. , 0163-1829 10.1103/PhysRevB.19.5495Pagliuso, P.G., Rettori, C., Sarrao, J.L., Cornelius, A., Hundley, M.F., Fisk, Z., Oseroff, S.B., (1999) Phys. Rev. B, 60, p. 13515Calderón, M.J., Wegener, L.G.L., Littlewood, P.B., (2004) Phys. Rev. B, 70, p. 092404Davidov, D., Maki, K., Orbach, R., Rettori, C., Chock, E.P., (1973) Solid State Commun., 12, p. 62

Electron Spin Resonance Above Tc In Layered Manganites

We have performed electron spin resonance (ESR) and dc magnetization measurements on single crystals of La2(1-x)Sr1+2xMn2O7 up to 800 K with special emphasis on the x = 0.4 composition. The ESR linewidth shows behavior similar to that observed in the three-dimensional perovskites and above ∼500 K can be described by a universal expression ΔHpp(T)=[C/Tχ(T)]ΔHpp (∞). The linewidth and the resonance field become anisotropic below ∼500 K. The anisotropy in the resonance field is proportional to the magnetization M, and we concluded that it is intrinsic to the system. We show that demagnetization effects can explain only part of the anisotropy. The remainder arises from short-range uniaxial terms in the Hamiltonian that are associated with the crystal field and Dzialozhinsky-Moriya interactions. The anisotropy in the linewidth is attributed to the easy-plane ferromagnetic ordering, which also arises from the short-range anisotropy.631717441311744136Ruddlesden, S.N., Popper, P., (1958) Acta Crystallogr., 11, p. 54Moritomo, Y., Asamitsu, A., Kuwahara, H., Tokura, Y., (1996) Nature (London), 380, p. 141Causa, M.T., Tovar, M., Caneiro, A., Prado, F., Ibanez, G., Ramos, C.A., Butera, A., Oseroff, S.B., (1998) Phys. Rev. B, 58, p. 3233Causa, M.T., Alejandro, G., Tovar, M., Pagliuso, P.G., Rettori, C., Oseroff, S.B., Subramanian, M.A., (1999) J. Appl. Phys., 85, p. 5408Huber, D.L., Alejandro, G., Caneiro, A., Causa, M.T., Prado, F., Tovar, M., Oseroff, S.B., (1999) Phys. Rev. B, 60, p. 12155Oseroff, S.B., Moreno, N.O., Pagliuso, P.G., Rettori, C., Huber, D.L., Gardner, J.S., Sarrao, J.L., Alascio, B.R., (2000) J. Appl. Phys., 87, p. 5810Seehra, M.S., Ibrahim, M.M., Babu, V.S., Srinivasan, G., (1996) J. Phys.: Condens. Matter, 8, p. 11283Dominguez, M., Lofland, S.E., Bhagat, S.M., Raychaudhuri, A.K., Ju, H.L., Venkates, T., Greene, R.L., (1996) Solid State Commun., 97, p. 193Lofland, S.E., Kim, P., Dahiroc, P., Bhagat, S.M., Tyagi, S.D., Karabashev, S.G., Shultyatev, D.A., Mukovskii, Y., (1997) Phys. Lett. A, 233, p. 476Kimura, T., Tomioka, Y., Kuwahara, H., Asamitsu, A., Tamura, M., Tokura, Y., (1996) Science, 274, p. 1698Perring, T.G., Aeppli, G., Moritomo, Y., Tokura, Y., (1997) Phys. Rev. Lett., 78, p. 3197Zhou, J.-S., Goodenough, J.B., Mitchell, J.F., (1998) Phys. Rev. B, 58, p. 579Zhou, J.-S., Goodenough, J.B., (1998) Phys. Rev. Lett., 80, p. 2665Kelley, T.M., Argyriou, D.N., Robinson, R.A., Nakotte, H., Mitchell, J.F., Osbron, R., Jorgensen, J.D., (1998) Physica B, 241-243, p. 439Heffner, R.H., MacLaughlin, D.E., Nieuwenhuys, G.J., Kimura, T., Luke, G.M., Tokura, Y., Uemura, Y.J., (1998) Phys. Rev. Lett., 81, p. 1706Potter, C.D., Swiatek, M., Bader, S.D., Argyriou, D.N., Mitchell, J.F., Miller, D.J., Hinks, D.G., Jorgensen, J.D., (1998) Phys. Rev. B, 57, p. 72Chauvet, O., Goglio, G., Molinie, P., Corraze, B., Brohan, L., (1998) Phys. Rev. Lett., 81, p. 1102Hirota, K., Moritomo, Y., Fujioka, H., Kubota, M., Yoshizawa, H., Endoh, Y., (1998) J. Phys. Soc. Jpn., 67, p. 3380Li, J.Q., Matsui, Y., Kimura, T., Tokura, Y., (1998) Phys. Rev. B, 57, pp. R3205Kimura, T., Kumai, R., Tokura, Y., Li, J.Q., Matsui, Y., (1998) Phys. Rev. B, 58, p. 11081Hayashi, T., Miura, N., Tokunaga, M., Kimura, T., Tokura, Y., (1998) J. Phys.: Condens. Matter, 10, p. 11525Suryanarayanan, R., Dhalenne, G., Revcolevschi, A., Prellier, W., Renard, J.P., Dupas, C., Caliebe, W., Chatterji, T., (2000) Solid State Commun., 113, p. 267Kubota, M., Fujioka, H., Ohoyama, K., Hirota, K., Moritomo, Y., Yoshizawa, H., Endoh, Y., (1999) J. Phys. Chem. Solids, 60, p. 116Bhagat, S.M., Lofland, S.E., Mitchell, J.F., (1999) Phys. Lett. A, 259, p. 326Kittel, C., (1997) Introduction to Solid State Physics, , Wiley, New YorkOkochi, M., (1970) J. Phys. Soc. Jpn., 28, p. 897Victoria, C., Barker, R.C., Yelon, A., (1967) Phys. Rev. Lett., 19, p. 792Nagata, K., (1976) J. Phys. Soc. Jpn., 40, p. 1209Nagata, K., Yamamoto, I., Takano, H., Yokozawa, Y., (1977) J. Phys. Soc. Jpn., 43, p. 857. , and references thereinHuber, D.L., Seehra, M.S., (1976) Phys. Status Solidi B, 74, p. 145Stanger, J.-L., Andre, J.-J., Turek, P., Hosokoshi, Y., Tamura, M., Kinoshita, M., Rey, P., Veciana, J., (1997) Phys. Rev. B, 55, p. 8398Van Vleck, J.H., (1950) Phys. Rev., 78, p. 266Kittel, C., (1948) Phys. Rev., 73, p. 15

Magnetically Frustrated Behavior In Multiferroics R Mn2 O 5 (r=bi, Eu, And Dy): A Raman Scattering Study

A temperature dependent Raman scattering study in multiferroic single crystals R Mn2 O5 (R=Bi, Eu, and Dy) was performed. The Raman spectra were measured in the range from 150 to 450 cm-1 involving mostly Mn-O-Mn bending vibrations, complementing our previous work in a higher frequency range involving Mn-O stretching modes. A number of studied phonons present anomalous frequency behavior below a characteristic temperature, T* ∼60-65 K, such as that found for the stretching modes. The sign and magnitude of such anomalous behavior appear to be correlated with the ionic radius of R, being softening for R=Bi and hardening for R=Eu and Dy in the range between TC TN and T*. The anomalous phonon behaviors in both bending and stretching modes are consistent with an interpretation in terms of the spin-phonon coupling in a scenario of strong magnetic correlations. © 2007 American Institute of Physics.1019Wang, J., (2003) Science, 299, p. 1719Hur, N., Park, S., Sharma, P.A., Ahn, J.S., Guha, S., Cheong, S.-W., (2004) Nature (London), 429, p. 392Alonso, J.A., Casais, M.T., Martínez-Lope, M.J., Martínez, J.L., Fernández-Díaz, M.T., (1997) J. Phys.: Condens. Matter, 9, p. 8515Kagomiya, I., Kohn, K., Uchiyama, T., (2002) Ferroelectrics, 280, p. 297Hur, N., Park, S., Sharma, P.A., Guha, S., Cheong, S.-W., (2004) Phys. Rev. Lett., 93, p. 107207Muoz, A., Alonso, J.A., Casais, M.T., Martínez-Lope, M.J., Martínez, J.L., Fernández-Díaz, M.T., (2002) Phys. Rev. B, 65, p. 144423Golovenchits, E.I., Sanina, V.A., Babinskii, A.V., (1997) JETP, 85, p. 156Chapon, L.C., Blake, G.R., Gutmann, M.J., Park, S., Hur, N., Radaelli, P.G., Cheong, S.-W., (2004) Phys. Rev. Lett., 93, p. 177402Blake, G.P., Chapon, L.C., Radaelli, P.G., Park, S., Hur, N., Cheong, S.-W., Rodríguez-Carvajal, J., (2005) Phys. Rev. B, 71, p. 214402Polyakov, V., Plakhty, V., Bonnet, M., Burlet, P., Regnault, L.-P., Gavrilov, S., Zobkalo, I., Smirnov, O., (2001) Physica B, 297, p. 208Higashiyama, D., Miyasaka, S., Kida, N., Arima, T., Tokura, Y., (2004) Phys. Rev. B, 70, p. 174405Ramirez, A.P., (2001) Handbook of Magnetic Materials, 13, pp. 423-520. , Elsevier, New YorkGarcía-Flores, A.F., (2006) Phys. Rev. B, 73, p. 104411Baltensperger, W., Helman, J.S., (1968) Helv. Phys. Acta, 41, p. 668Granado, E., (2001) Phys. Rev. Lett., 86, p. 5385Sushkov, A.B., Tchernyshyov, O., Ratcliff, I.I.W., Cheong, S.-W., Drew, H.D., (2004) Phys. Rev. Lett., 94, p. 13720

Esr Of Gd3+ In The Kondo-lattice Compound Ybagcu4 And Its Reference Compounds Ragcu4 (r=y,lu)

Low-temperature (T<30 K) electron-spin-resonance (ESR) experiments of Gd3+ diluted in the Kondo-lattice compound YbAgCu4 and its reference compounds YAgCu4 and LuAgCu4 are interpreted in terms of an enhanced density of states at the Fermi level for the Yb-based compound. The results of susceptibility and ESR (Korringa rate and g-shift) measurements show negligible electron-electron exchange enhancement for all the studied compounds. The exchange interaction between the Gd3+ local moment and the conduction electrons (c-e) is c-e wave vector dependent in all three compounds.561489338937Falicov, L.M., Hanke, W., Maple, M.B., (1981) Valence Fluctuation in Solids, , North-Holland, AmsterdamWachter, P., Boppart, H., (1982) Valence Instabilities, , North-Holland, AmsterdamMuller-Hartmann, E., Roden, B., Wohlleben, D., (1984) Valence Fluctuation, , North-Holland, AmsterdamBarberis, G.E., Foglio, M.E., Crow, J.E., Schlottmann, P., (1991) Valence Fluctuations, , North-Holland, AmsterdamKojima, K., Nakai, Y., Sizuki, T., Asano, H., Izumi, F., Fujita, T., Hihara, T., (1990) J. Phys. Soc. Jpn., 59, p. 792Rossel, C., Yang, K.N., Maple, M.B., Fisk, Z., Zirngiebl, E., Thompson, J.D., (1987) Phys. Rev. B, 35, p. 1914Fisk, Z., Maple, M.B., (1992) J. Alloys Compd., 183, p. 303Pillmayr, N., Bauer, E., Yoshimura, K., (1992) J. Magn. Magn. Mater., 104-107, p. 639Rajan, V.T., (1983) Phys. Rev. Lett., 51, p. 308Coqblin, B., Schrieffer, J.R., (1963) Phys. Rev., 185, p. 847Rettori, C., Oseroff, S.B., Rao, D., Pagliuso, P.G., Barberis, G.E., Sarrao, J., Fisk, Z., Hundley, M., (1997) Phys. Rev. B, 55, p. 1016Sarrao, J.L., Benton, C.L., Fisk, Z., Lawrence, J.M., Mandrus, D., Thompson, J.D., (1996) Physica B, 223-224, p. 366Sarrao, J.L., Immer, C.D., Benton, C.L., Fisk, Z., Lawrence, J.M., Mandrus, M., Thompson, J.D., (1996) Phys. Rev. B, 54, p. 12207Bachmann, R., DiSalvo, F.J., Geballe, T.H., Greene, R.L., Howard, R.E., King, C.N., Kivisch, H.C., Zubek, R.B., (1972) Rev. Sci. Instrum., 43, p. 205Feher, G., Kip, A.F., (1955) Phys. Rev., 98, p. 337Dyson, F.J., (1955) Phys. Rev., 98, p. 349Pake, G.E., Purcell, E.M., (1948) Phys. Rev., 74, p. 1184Yosida, K., (1957) Phys. Rev., 106, p. 893Korringa, J., (1950) Physica, 16, p. 601. , AmsterdamMoriya, T., (1963) J. Phys. Soc. Jpn., 18, p. 516Narath, A., (1967) Phys. Rev., 163, p. 232Davidov, D., Maki, K., Orbach, R., Rettori, C., Chock, E.P., (1973) Solid State Commun., 12, p. 621Davidov, D., Orbach, R., Rettori, C., Shaltiel, D., Tao, L.J., Ricks, B., (1971) Phys. Lett., 35 A, p. 339Rettori, C., Kim, H.M., Chock, E.P., Davidov, D., (1974) Phys. Rev. B, 10, p. 1826Narath, A., Weaver, H.T., (1968) Phys. Rev., 175, p. 373Shaw, R.W., Warren, W.W., (1971) Phys. Rev. B, 3, p. 1562Davidov, D., Chelkowski, A., Rettori, C., Orbach, R., Maple, M.B., (1973) Phys. Rev. B, 7, p. 1029Barberis, G.E., Davidov, D., Donoso, J.P., Rettori, C., Suassuna, J.F., Dokter, H.D., (1979) Phys. Rev. B, 19, p. 5495Abragam, A., Bleaney, B., (1970) EPR of Transition Ions, , Clarendon, OxfordSchlottmann, P., (1985) Theory of Heavy Fermion and Valence Fluctuation, p. 68. , edited by T. Kasuya and T. Saso Springer-Verlag. BerlinTsujii, N., He, J., Yoshimura, K., Kosuge, K., Michor, H., Kreiner, K., Hilscher, G., (1997) Phys. Rev. B, 55, p. 1032Watson, R.E., Freeman, A.J., Koide, S., (1969) Phys. Rev. B, 186, p. 625Continentino, M.A., (1993) Phys. Rev. B, 47, p. 11587Barberis, G.E., Davidov, D., Rettori, C., Donoso, J.P., Torriani, I., Gandra, F.C.G., (1980) Phys. Rev. Lett., 45, p. 1966Schaeffer, H., Elschner, B., (1983) Z. Phys. B, 53, p. 109Gandra, F.G., Schultz, S., Oseroff, S.B., Fisk, Z., Smith, J.L., (1985) Phys. Rev. Lett., 55, p. 2719Gandra, F.G., Pontes, M.J., Schultz, S., Oseroff, S.B., (1987) Solid State Commun., 64, p. 85

Role Of Oxygen Vacancies In The Magnetic And Dielectric Properties Of The High-dielectric-constant System Cacu3 Ti4 O12: An Electron-spin Resonance Study

We report experiments of electron spin resonance (ESR) of Cu2+ in polycrystalline samples of CaCu3 Ti4 O12 post-annealed in different atmospheres. After being synthesized by solid state reaction, pellets of CaCu3 Ti4 O12 were annealed for 24 h at 1000°C under air, Ar or O2. Our temperature dependent ESR data revealed for all samples nearly temperature independent g value (2.15(1)) and linewidth for T TN ≈25 K. However, the values of ESR linewidth are strongly affected by the oxygen content in the sample. For instance, argon post-annealed samples show a much larger linewidth than the O2 or air post-annealed samples. We attribute this broadening to an increase of the dipolar homogeneous broadening of the Cu2+ ESR lines due to the presence of oxygen vacancies which induce an S=1 2 spin inside the TiO6 octahedra. Correlation between a systematic dependence of the ESR linewidth on the oxygen content and the high dielectric constant of these materials is addressed. Also, ESR, magnetic susceptibility, and specific heat data for a single crystal of CaCu3 Ti4 O12 and for polycrystals of CdCu3 Ti4 O12 are reported. © 2006 The American Physical Society.7322Subramanian, M.A., Li, D., Duan, N., Reisner, B., Sleight, A.W., (2000) J. Solid State Chem., 151, p. 323. , JSSCBI 0022-4596 10.1006/jssc.2000.8703Ramirez, A.P., Subramanian, M.A., Gardel, M., Blumberg, G., Li, D., Vogt, T., Shapiro, S.M., (2000) Solid State Commun., 151, p. 217. , SSCOA4 0038-1098Homes, C.C., Vogt, T., Shapiro, S.M., Wakimoto, S., Ramirez, A.P., (2001) Science, 293, p. 673. , SCIEAS 0036-8075 10.1126/science.292.5517.673Lunkenheimer, P., Bobnar, V., Pronin, A.V., Ritus, A.I., Volkov, A.A., Loidl, A., (2002) Phys. Rev. B, 66, p. 052105. , PRBMDO 0163-1829 10.1103/PhysRevB.66.052105Homes, C.C., Vogt, T., Shapiro, S.M., Wakimoto, S., Subramanian, M.A., Ramirez, A.P., (2003) Phys. Rev. B, 67, p. 092106. , PRBMDO 0163-1829 10.1103/PhysRevB.67.092106Sinclair, D.C., Admas, T.B., Morrison, F.D., West, A.R., (2002) Appl. Phys. Lett., 80, p. 2153. , APPLAB 0003-6951 10.1063/1.1463211Giulloto, E., Mozzati, M.C., Azzoni, C.B., Massarotti, V., Bini, M., (2004) Ferroelectrics, 298, p. 61. , FEROA8 0015-0193Mozzati, M.C., Azzoni, C.B., Capsoni, D., Bini, M., Massarotti, V., (2003) J. Phys.: Condens. Matter, 15, p. 7365. , JCOMEL 0953-8984 10.1088/0953-8984/15/43/018Subramanian, M.A., Sleight, A.W., (2002) Solid State Sci., 4, p. 347. , SSSCFJ 1293-2558 10.1016/S1293-2558(01)01262-6Fang, L., Shen, M., Cao, W., (2004) J. Appl. Phys., 95, p. 6483. , JAPIAU 0021-8979 10.1063/1.1728308Koitzsch, A., Blumberg, G., Gozar, A., Dennis, B., Ramirez, A.P., Trebst, S., Wakimoto, S., (2002) Phys. Rev. B, 65, p. 052406. , PRBMDO 0163-1829 10.1103/PhysRevB.65.052406Bosman, A.J., Van Daal, H.J., (1970) Adv. Phys., 19, p. 1. , ADPHAH 0001-8732 10.1080/00018737000101071Lenjer, S., Schirmer, O.F., Hesse, H., Kool, T.W., (2002) Phys. Rev. B, 66, p. 165106. , PRBMDO 0163-1829 10.1103/PhysRevB.66.165106Bednorz, J.G., Mller, K.A., (1988) Rev. Mod. Phys., 60, p. 585. , RMPHAT 0034-6861 10.1103/RevModPhys.60.585Salamon, M.B., Jaime, M., (2001) Rev. Mod. Phys., 73, p. 583. , RMPHAT 0034-6861 10.1103/RevModPhys.73.583Scharfschwerdt, R., Mazur, A., Schirmer, O.F., Hesse, H., Mendricks, S., (1996) Phys. Rev. B, 54, p. 15284. , PRBMDO 0163-1829 10.1103/PhysRevB.54.15284Laguta, V.V., Slipenyuk, A.M., Bykov, I.P., Glinchuck, M.D., Maglione, M., Michau, D., Rosa, J., Jastrabik, L., (2005) Appl. Phys. Lett., 87, p. 022903. , APPLAB 0003-6951 10.1063/1.1954900Cohn, J.L., Peterca, M., Neumeier, J.J., (2005) J. Appl. Phys., 97, p. 034102. , JAPIAU 0021-8979 10.1063/1.1834976Abragam, A., Bleaney, B., (1670) Electron Paramagnetic Resonance of Transition Ions, , Clarendon, OxfordPoole, C.P., Farach, H.A., (1971) Relaxation in Magnetic Resonance, , Academic, New YorkVan Vleck, J.H., (1948) Phys. Rev., 74, p. 1168. , PHRVAO 0031-899X 10.1103/PhysRev.74.1168Anderson, P.W., Weiss, P.R., (1953) Rev. Mod. Phys., 25, p. 269. , RMPHAT 0034-6861 10.1103/RevModPhys.25.269Wu, L., Zhu, Y., Park, S., Shapiro, S., Shirane, G., Tafto, J., (1953) Rev. Mod. Phys., 25, p. 269. , RMPHAT 0034-6861 10.1103/RevModPhys.25.26

Reentrant Spin-Peierls Transition in Mg-Doped CuGeO_3

We report a synchrotron x-ray scattering study of the diluted spin-Peierls (SP) material Cu_{1-x}Mg_xGeO_3. In a recent paper we have shown that the SP dimerization attains long-range order only for x < x_c = 0.022(0.001). Here we report that the SP transition is reentrant in the vicinity of the critical concentration x_c. This is manifested by broadening of the SP dimerization superlattice peaks below the reentrance temperature, T_r, which may mean either the complete loss of the long-range SP order or the development of a short-range ordered component within the long-range ordered SP state. Marked hysteresis and very large relaxation times are found in the samples with Mg concentrations in the vicinity of x_c. The reentrant transition is likely related to the competing Neel transition which occurs at a temperature similar to T_r. We argue that impurity-induced competing interchain interactions play an essential role in these phenomena.Comment: 5 pages, 4 embedded eps figure