Neutron-diffraction study of field-induced transitions in the heavy-fermion compound Ce2RhIn8

We present neutron diffraction measurements in high magnetic fields (0 to 14.5 T) and at low temperatures (2.5, 2.3, 0.77 and 0.068 K) on single crystals of the tetragonal heavy fermion antiferromagnet Ce2RhIn8. For B//[110] the field dependence of selected magnetic and nuclear reflections reveals that the material undergoes several transitions, the temperature dependence of which suggests a complex B-T phase diagram. We present the detailed evolution of the integrated intensities of selected reflections and discuss the associated field-induced transitions.Comment: 12 pages, 3 figures Proceeding Euro-conference "Properties of Condensed Matter probed by x-ray and neutron scattering"; to appear in Physica

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

The symmetry of the superconducting order parameter in PuCoGa5_5

The symmetry of the superconducting order parameter in single-crystalline PuCoGa$_5$ ($T_{\rm c} = 18.5$ K) is investigated via zero- and transverse- field muon spin relaxation ($\mu$SR) measurements, probing the possible existence of orbital and/or spin moments (time reversal-symmetry violation TRV) associated with the superconducting phase and the in-plane magnetic-field penetration depth $\lambda(T)$ in the mixed state, respectively. We find no evidence for TRV, and show that the superfluid density, or alternatively, $\Delta\lambda(T) = \lambda(T) - \lambda(0)$, are $\propto T$ for $T/T_{\rm c} \leq 0.5$. Taken together these measurements are consistent with an even-parity (pseudo-spin singlet), d-wave pairing state.Comment: 4 pages, 5 figure

ARPES Study of X-Point Band Overlaps in LaB6_6 and SmB6_6 - Contrast to SrB6_6 and EuB6_6

In contrast to our recent finding of an X-point band gap in divalent hexaborides, we report here that angle resolved photoemission spectroscopy (ARPES) data shows that the gap is absent for trivalent LaB$_6$ and is absent or nearly so for mixed valent SmB$_6$. This finding demonstrates a nontrivial evolution of the band structure from divalent to trivalent hexaborides.Comment: submitted to SCES '0

Magnetism and superconductivity in CeRh_{1-x}Ir_xIn_5 heavy fermion materials

We report on zero-field muon spin relaxation studies of cerium based heavy-fermion materials CeRh_{1-x}Ir_xIn_5. In the superconducting x=0.75 and 1 compositions muon spin relaxation functions were found to be temperature independent across T_c; no evidence for the presence of electronic magnetic moments was observed. The x=0.5 material is antiferromagnetic below T_N=3.75 K and superconducting below T_c=0.8 K. Muon spin realxation spectra show the gradual onset of damped coherent oscillations characteristic of magnetic order below T_N. At 1.65 K the total oscillating amplitude accounts for at least 85% of the sample volume. No change in muon precession frequency or amplitude is detected on cooling below T_c, indicating the microscopic coexistence of magnetism and superconductivity in this material.Comment: 6 pages with 3 figures. Revision with corrected axis label (mK) in Fig.

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

Effect of La doping on magnetic structure in heavy fermion CeRhIn5

The magnetic structure of Ce0.9La0.1RhIn5 is measured using neutron diffraction. It is identical to the incommensurate transverse spiral for CeRhIn5, with a magnetic wave vector q_M=(1/2,1/2,0.297), a staggered moment of 0.38(2)Bohr magneton per Ce at 1.4K and a reduced Neel temperature of 2.7 K.Comment: 5 pages, 2 figures, 1 table. Conf. SCES'200

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

Vibrational And Electronic Excitations In The (ce,la)m In5 (m=co,rh) Heavy-fermion Family

We present a systematic study at ambient pressure of the phononic and electronic Raman-active excitations in the ab plane of the (Ce,La)M In5 (M=Co,Rh) heavy-fermion family. We found that the characteristic Raman spectra of this family of compounds display two phonon modes at ∼38 and ∼165 cm-1 and a broad electronic background centered at ∼40 cm-1. For CeCoIn5, the temperature dependence of these excitations shows anomalous behavior near T* =45 K that may indicate a nontrivial renormalization of the electronic structure driven by strong correlations between hybridized 4f electrons. © 2007 The American Physical Society.754Heffner, R.H., Norman, M.R., (1996) Comments Condens. Matter Phys., 17, p. 361. , CCMPEB 0885-4483Anderson, P.W., (1961) Phys. Rev., 124, p. 41. , PHRVAO 0031-899X 10.1103/PhysRev.124.41Coqblin, B., Schrieffer, J.R., (1969) Phys. Rev., 185, p. 847. , PHRVAO 0031-899X 10.1103/PhysRev.185.847Rajan, V.T., (1983) Phys. Rev. Lett., 51, p. 308. , PRLTAO 0031-9007 10.1103/PhysRevLett.51.308Rossel, C., Yang, K.N., Maple, M.B., Fisk, Z., Zirngiebl, E., Thompson, J.D., (1987) Phys. Rev. B, 35, p. 1914. , See, for example, PRBMDO 0163-1829 10.1103/PhysRevB.35.1914Nakatsuji, S., Pines, D., Fisk, Z., (2004) Phys. Rev. Lett., 92, p. 016401. , PRLTAO 0031-9007 10.1103/PhysRevLett.92.016401Nakatsuji, S., Yeo, S., Balicas, L., Fisk, Z., Schlottmann, P., Pagliuso, P.G., Moreno, N.O., Thompson, J.D., (2002) Phys. Rev. Lett., 89, p. 106402. , PRLTAO 0031-9007 10.1103/PhysRevLett.89.106402Curro, N.J., Sarrao, J.L., Thompson, J.D., Pagliuso, P.G., Kos, Š., Abanov, At., Pines, D., (2003) Phys. Rev. Lett., 90, p. 227202. , PRLTAO 0031-9007 10.1103/PhysRevLett.90.227202Petrovic, C., Movshovich, R., Jaime, M., Pagliuso, P.G., Hundley, M.F., Sarrao, J.L., Fisk, Z., Thompson, J.D., (2001) Europhys. Lett., 53, p. 354. , EULEEJ 0295-5075 10.1209/epl/i2001-00161-8Petrovic, C., Pagliuso, P.G., Hundley, M.F., Movshovich, R., Sarrao, J.L., Fisk, Z., Thompson, J.D., (2001) J. Phys.: Condens. Matter, 13, p. 337. , JCOMEL 0953-8984 10.1088/0953-8984/13/17/103Sidorov, V.A., Nicklas, M., Pagliuso, P.G., Sarrao, J.L., Bang, Y., Balatsky, A.V., Thompson, J.D., (2002) Phys. Rev. Lett., 89, p. 157004. , PRLTAO 0031-9007 10.1103/PhysRevLett.89.157004Bianchi, A., Movshovich, R., Vekhter, I., Pagliuso, P.G., Sarrao, J.L., (2003) Phys. Rev. Lett., 91, p. 257001. , PRLTAO 0031-9007 10.1103/PhysRevLett.91.257001Bianchi, A., Movshovich, R., Capan, C., Pagliuso, P.G., Sarrao, J.L., (2003) Phys. Rev. Lett., 91, p. 187004. , PRLTAO 0031-9007 10.1103/PhysRevLett.91.187004Singley, E.J., Basov, D.N., Bauer, E.D., Maple, M.B., (2002) Phys. Rev. B, 65, p. 161101. , PRBMDO 0163-1829 10.1103/PhysRevB.65.161101Klein, M.V., (1983) Light Scattering in Solids I, 8, p. 147. , edited by M. Cardona, Topics in Applied Physics, Vol. Springer-Verlag, BerlinZawadowski, A., Cardona, M., (1990) Phys. Rev. B, 42, p. 10732. , PRBMDO 0163-1829 10.1103/PhysRevB.42.10732Menéndez, J., Cardona, M., (1984) Phys. Rev. B, 29, p. 2051. , PRBMDO 0163-1829 10.1103/PhysRevB.29.2051Harrison, N., (2004) Phys. Rev. Lett., 93, p. 186405. , PRLTAO 0031-9007 10.1103/PhysRevLett.93.186405Nayak, P., Ojha, B., Mohanty, S., Behera, S.N., (2002) Int. J. Mod. Phys. B, 16, p. 3595. , IJPBEV 0217-9792Hall, D., (2001) Phys. Rev. B, 64, p. 064506. , PRBMDO 0163-1829 10.1103/PhysRevB.64.064506Razafimandiby, H., Fulde, P., Keller, J., (1989) Z. Phys. B: Condens. Matter, 54, p. 111. , ZPCMDN 0722-3277 10.1007/BF01388062Christianson, A.D., (2004) Phys. Rev. B, 70, p. 134505. , PRBMDO 0163-1829 10.1103/PhysRevB.70.13450

Ultrafast quasiparticle relaxation dynamics in normal metals and heavy fermion materials

We present a detailed theoretical study of the ultrafast quasiparticle relaxation dynamics observed in normal metals and heavy fermion materials with femtosecond time-resolved optical pump-probe spectroscopy. For normal metals, a nonthermal electron distribution gives rise to a temperature (T) independent electron-phonon relaxation time at low temperatures, in contrast to the T^{-3}-divergent behavior predicted by the two-temperature model. For heavy fermion compounds, we find that the blocking of electron-phonon scattering for heavy electrons within the density-of-states peak near the Fermi energy is crucial to explain the rapid increase of the electron-phonon relaxation time below the Kondo temperature. We propose the hypothesis that the slower Fermi velocity compared to the sound velocity provides a natural blocking mechanism due to energy and momentum conservation laws.Comment: 10 pages, 11 figure