Non-Fermi Liquid behavior in CeIrIn5_5 near a metamagnetic transition

We present specific heat and resistivity study of CeIrIn5 in magnetic fields up to 17 T and temperature down to 50 mK. Both quantities were measured with the magnetic field parallel to the c-axis (H || [001]) and within the a-b plane (H \perp [001]). Non-Fermi-liquid (NFL) behavior develops above 12 T for H || [001]. The Fermi liquid state is much more robust for H \perp [001] and is suppressed only moderately at the highest applied field. Based on the observed trends and the proximity to a metamagnetic phase transition, which exists at fields above 25 T for H || [001], we suggest that the observed NFL behavior in CeIrIn5 is a consequence of a metamagnetic quantum critical point.Comment: 5 pages, 4 figures, submitted to Phys. Rev. Letter

Thermal stability of sputter-deposited 330 austenitic stainless-steel thin films with nanoscale growth twins

We have explored the thermal stability of nanoscale growth twins in sputter-deposited 330 stainless-steel (SS) films by vacuum annealing up to 500 °C. In spite of an average twin spacing of only 4 nm in the as-deposited films, no detectable variation in the twin spacing or orientation of twin interfaces was observed after annealing. An increase in the average columnar grain size was observed after annealing. The hardness of 330 SS films increases after annealing, from 7 GPa for as-deposited films to around 8 GPa for annealed films, while the electrical resistivity decreases slightly after annealing. The changes in mechanical and electrical properties after annealing are interpreted in terms of the corresponding changes in the residual stress and microstructure of the films

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

Theory of a Higher Order Phase Transition: Superconducting Transition in BKBO

We describe here the properties expected of a higher (with emphasis on the order fourth) order phase transition. The order is identified in the sense first noted by Ehrenfest, namely in terms of the temperature dependence of the ordered state free energy near the phase boundary. We have derived an equation for the phase boundary in terms of the discontinuities in thermodynamic observables, developed a Ginzburg-Landau free energy and studied the thermodynamic and magnetic properties. We also discuss the current status of experiments on $Ba_{0.6}K_{0.4}BiO_3$ and other $BiO_3$ based superconductors, the expectations for parameters and examine alternative explanations of the experimental results.Comment: 18 pages, no figure

Field-tuned Quantum Critical Point In Cecoin 5 Near The Superconducting Upper Critical Field

We report a systematic study of high-magnetic-field specific heat and resistivity in single crystals of CeCoIn 5 for the field oriented in the basal plane (H||ab)of this tetragonal heavy fermion superconductor. We observe a divergent electronic specific heat as well as an enhanced A coefficient of the T 2 law in resistivity at the lowest temperatures, as the field approaches the upper critical field of the superconducting transition. Together with the results for field along the tetragonal axis (H||c), the emergent picture is that of a magnetic-field-tuned quantum critical point which exists in the vicinity of the superconducting H c2 0 despite a variation of a factor of 2.4 in H c2 0 for different field orientations. This suggests that an underlying physical reason exists for the superconducting H c2 0 to coincide with the quantum critical field. Moreover, we show that the recovery of a Fermi-liquid ground state with increasing magnetic field is more gradual, meaning that the fluctuations responsible for the observed quantum critical phenomena are more robust with respect to magnetic field, when the magnetic field is applied in plane. Together with the close proximity of the quantum critical point and H c2 0 in CeCoIn 5 for both field orientations, the anisotropy in the recovery of the Fermi-liquid state might constitute an important piece of information in identifying the nature of the fluctuations that become critical. ©2005 The American Physical Society.7110Petrovic, C., Pagliuso, P.G., Hundley, M.F., Movshovich, R., Sarrao, J.L., Thompson, J.D., Fisk, Z., Monthoux, P., (2001) J. Phys.: Condens. Matter, 13, pp. L337Movshovich, R., Jaime, M., Thompson, J.D., Petrovic, C., Fisk, Z., Pagliuso, P.G., Sarrao, J.L., (2001) Phys. Rev. Lett., 86, p. 5152Izawa, K., Yamaguchi, H., Matsuda, Y., Shishido, H., Settai, R., Onuki, Y., (2001) Phys. Rev. Lett., 87, p. 057002Bianchi, A., Movshovich, R., Oeschler, N., Gegenwart, P., Steglich, F., Thompson, J.D., Pagliuso, P.G., Sarrao, J.L., (2002) Phys. Rev. Lett., 89, p. 137002Bianchi, A., Movshovich, R., Capan, C., Pagliuso, P.G., Sarrao, J.L., (2003) Phys. Rev. Lett., 91, p. 187004Radovan, H.A., Forture, N.A., Murphy, T.P., Hannahs, S.T., Palm, E.C., Tozer, S.W., Hall, D., (2003) Nature (London), 425, p. 51Kim, J.S., Alwood, J., Stewart, G.R., Sarrao, J.L., Thompson, J.D., (2001) Phys. Rev. B, 64, p. 134524Kohori, Y., Yamato, Y., Iwamoto, Y., Kohara, T., Bauer, E.D., Maple, M.B., Sarrao, J.L., (2001) Phys. Rev. B, 64, p. 134526Ott, H.R., Rudigier, H., Rice, T.M., Ueda, K., Fisk, Z., Smith, J.L., (1984) Phys. Rev. Lett., 52, p. 1915Sidorov, V.A., Nicklas, M., Pagliuso, P.G., Sarrao, J.L., Bang, Y., Balatsky, A.V., Thompson, J.D., (2002) Phys. Rev. Lett., 89, p. 157004Sparn, G., Borth, R., Lengyel, E., Pagliuso, P.G., Sarrao, J.L., Steglich, F., Thompson, J.D., (2002) Physica B, 319, p. 262Shishido, H., Ueda, T., Hashimoto, S., Kubo, T., Settai, R., Harima, H., Onuki, Y., (2003) J. Phys.: Condens. Matter, 15, pp. L499Kohori, Y., Saito, H., Kobayashi, Y., Taira, H., Iwamoto, Y., Kohara, T., Matsumoto, T., Sarrao, J.L., (2004) J. Magn. Magn. Mater., 272-276, p. 189Paglione, J., Tanatar, M.A., Hawthorn, D.G., Boaknin, E., Hill, R.W., Ronning, F., Sutherland, M., Canfield, P.C., (2003) Phys. Rev. Lett., 91, p. 246405Bianchi, A., Movshovich, R., Vekhter, I., Pagliuso, P.G., Sarrao, J.L., (2003) Phys. Rev. Lett., 91, p. 257001Paglione, J., Tanatar, M.A., Hawthorn, D.G., Boaknin, E., Hill, R.W., Ronning, F., Sutherland, M., Canfield, P.C., cond-mat/0405157 (unpublished)Bauer, E.D., Capan, C., Ronning, F., Movshovich, R., Thompson, J.D., Sarrao, J.L., (2005) Phys. Rev. Lett., 94, p. 047001Gegenwart, P., Custers, J., Geibel, C., Neumaier, K., Tayama, T., Tenya, K., Trovarelli, O., Steglich, F., (2002) Phys. Rev. Lett., 89, p. 056402Custers, J., Gegenwart, P., Wilhelm, H., Neumaier, K., Tokiwa, Y., Trovarelli, O., Geibel, C., Coleman, P., (2003) Nature (London), 424, p. 504Moriya, T., Takimoto, T., (1995) J. Phys. Soc. Jpn., 64, p. 960Rosch, A., (2000) Phys. Rev. B, 62, p. 4945notenoteSettai, R., Shishido, H., Ikeda, S., Murakawa, Y., Nakashima, M., Aoki, D., Haga, Y., Onuki, Y., (2001) J. Phys.: Condens. Matter, 13, pp. L627Hall, D., Palm, E.C., Murphy, T.P., Tozer, S.W., Fisk, Z., Alver, U., Goodrich, R.G., Ebihara, T., (2001) Phys. Rev. B, 64, p. 212508Hurd, C.M., (1972) Hall Effect in Metals and Alloys, , Plenum, New YorkMalinowski, A., unpublishedWon, H., Maki, K., Haas, S., Oeschler, N., Weickert, F., Gegenwart, P., (2004) Phys. Rev. B, 69, pp. 180504RRamazashvili, R., Coleman, P., (1997) Phys. Rev. Lett., 79, p. 3752Howell, P.C., Schofield, A.J., cond-mat/0103191 (unpublished

Grain boundary effects on magnetotransport in bi-epitaxial films of La0.7_{0.7}Sr0.3_{0.3}MnO3_3

The low field magnetotransport of La$_{0.7}$Sr$_{0.3}$MnO$_3$ (LSMO) films grown on SrTiO$_3$ substrates has been investigated. A high qualtity LSMO film exhibits anisotropic magnetoresistance (AMR) and a peak in the magnetoresistance close to the Curie temperature of LSMO. Bi-epitaxial films prepared using a seed layer of MgO and a buffer layer of CeO$_2$ display a resistance dominated by grain boundaries. One film was prepared with seed and buffer layers intact, while a second sample was prepared as a 2D square array of grain boundaries. These films exhibit i) a low temperature tail in the low field magnetoresistance; ii) a magnetoconductance with a constant high field slope; and iii) a comparably large AMR effect. A model based on a two-step tunneling process, including spin-flip tunneling, is discussed and shown to be consistent with the experimental findings of the bi-epitaxial films.Comment: REVTeX style; 14 pages, 9 figures. Figure 1 included in jpeg format (zdf1.jpg); the eps was huge. Accepted to Phys. Rev.

Hall effect in YbXCu4 and the role of carrier density in the YbInCu4 valence transition

An unrealistically large value of the Gruneisen parameter is required to explain the valence transition which occurs at 42 K in YbInCu4 as due to a Kondo Volume Collapse. A hint as to the origin of the transition lies in the large change in carrier density which occurs at the transition, from trivalent semimetallic behavior at high temperature to mixed valent metallic behavior at low temperature. In this paper we report measurements of the Hall coefficient RH for temperatures in the range 15-300 K for a series of RXCu4 compounds (R = Yb, Lu and X = Au, Zn, Cd, Mg, Tl) that form in the cubic C15b structure. For all X the Hall coefficients are small (∼10-10 m3/C) so that the transport appears to be metallic. The observation that low carrier density is unique to RInCu4 leads us to hypothesize that the valence transition (which is also unique to YbInCu4) is connected with the existence of a quasigap, which is a common feature of the band structure of RXCu4. The quasigap allows for two competing hybridization states of the 4f electrons: a small TK semimetallic state and a large TK metallic state. © 1998 Elsevier Science Ltd. All rights reserved