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.

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

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

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

Magnetic Structure Of R 2 Coga 8 (r = Gd, Tb, And Dy): Structural Tuning Of Magnetic Properties In Layered Ga-based Intermetallic Compounds

In this work we have determined the magnetic structure of R2CoGa8 (R= Gd, Tb, and Dy) intermetallic compounds using x-ray resonant magnetic scattering in order to study the evolution of the anisotropic magnetic properties along the series for R= Gd-Tm. The three compounds have a commensurate antiferromagnetic spin structure with a magnetic propagation vector τâ- = (12,12,12) and a Néel temperature of approximately 20, 28.5, and 15.2 K for R= Gd, Tb, and Dy, respectively. The critical exponent β obtained from the temperature dependence of the magnetic peaks suggest a three-dimensional universality class for the three compounds. Comparing the simulated and integrated intensities we conclude that the magnetic moment direction is in the ab plane for the Gd2CoGa8 compound and parallel to the c axis for the Tb2CoGa8 and Dy2CoGa8 compounds. The evolution of the magnetic properties of the R2CoGa8 series for R= Gd-Tm is discussed taking into account the indirect Ruderman-Kittel-Kasuya-Yoshida interaction and crystalline-electric field effects. The comparison between the reported magnetic properties of the Ga-based compounds with those for the In-based isostructural family reveals differences in their exchange couplings that contribute to the understanding of the role of the f-electron magnetism in these classes of materials. © 2014 American Physical Society.8911Thompson, J., Fisk, Z., (2012) J. Phys. Soc. Jpn., 81, p. 011002. , JUPSAU 0031-9015 10.1143/JPSJ.81.011002Movshovich, R., Jaime, M., Thompson, J.D., Petrovic, C., Fisk, Z., Pagliuso, P.G., Sarrao, J.L., (2001) Phys. Rev. Lett., 86, p. 5152. , PRLTAO 0031-9007 10.1103/PhysRevLett.86.5152Sarrao, J., Morales, L., Thompson, J., Scott, B., Stewart, G., Wastin, F., Rebizant, J., Lander, G., (2002) Nature (London), 420, p. 297. , NATUAS 0028-0836 10.1038/nature01212Curro, N.J., Sarrao, J.L., Thompson, J.D., Pagliuso, P.G., Kos, S., Abanov, Ar., Pines, D., (2003) Phys. Rev. Lett., 90, p. 227202. , 10.1103/PhysRevLett.90.227202Hegger, H., Petrovic, C., Moshopoulou, E.G., Hundley, M.F., Sarrao, J.L., Fisk, Z., Thompson, J.D., (2000) Phys. Rev. Lett., 84, p. 4986. , PRLTAO 0031-9007 10.1103/PhysRevLett.84.4986Thompson, J., Movshovich, R., Fisk, Z., Bouquet, F., Curro, N., Fisher, R., Hammel, P., Jaime, M., (2001) J. Magn. Magn. Mater., p. 5. , JMMMDC 0304-8853 10.1016/S0304-8853(00)00602-8Pagliuso, P., Garcia, D., Miranda, E., Granado, E., Serrano, R., Giles, C., Duque, J., Thompson, J., (2006) J. Appl. Phys., 99, pp. 08P703. , JAPIAU 0021-8979 10.1063/1.2176109Lora-Serrano, R., Giles, C., Granado, E., Garcia, D.J., Miranda, E., Agüero, O., Mendonça Ferreira, L., Pagliuso, P.G., (2006) Phys. Rev. B, 74, p. 214404. , PRBMDO 1098-0121 10.1103/PhysRevB.74.214404Adriano, C., Lora-Serrano, R., Giles, C., De Bergevin, F., Lang, J.C., Srajer, G., Mazzoli, C., Pagliuso, P.G., (2007) Phys. Rev. B, 76, p. 104515. , PRBMDO 1098-0121 10.1103/PhysRevB.76.104515Pagliuso, P.G., Thompson, J.D., Hundley, M.F., Sarrao, J.L., Fisk, Z., (2001) Phys. Rev. B, 63, p. 054426. , PRBMDO 1098-0121 10.1103/PhysRevB.63.054426Pagliuso, P.G., Thompson, J.D., Hundley, M.F., Sarrao, J.L., (2000) Phys. Rev. B, 62, p. 12266. , PRBMDO 0163-1829 10.1103/PhysRevB.62.12266Bao, W., Pagliuso, P.G., Sarrao, J.L., Thompson, J.D., Fisk, Z., Lynn, J.W., (2001) Phys. Rev. B, 64, p. 020401. , R). PRBMDO 0163-1829 10.1103/PhysRevB.64.020401Granado, E., Pagliuso, P.G., Giles, C., Lora-Serrano, R., Yokaichiya, F., Sarrao, J.L., (2004) Phys. Rev. B, 69, p. 144411. , PRBMDO 1098-0121 10.1103/PhysRevB.69.144411Adriano, C., Giles, C., Coelho, L., Faria, G., Pagliuso, P., (2009) Physica B, 404, p. 3289. , PHYBE3 0921-4526 10.1016/j.physb.2009.07.127Adriano, C., Aliouane, N., Mardegan, J.R.L., Coelho, L.N., Escovi, R.V., Pagliuso, P.G., Giles, C., (unpublished)Johnson, R.D., Frawley, T., Manuel, P., Khalyavin, D.D., Adriano, C., Giles, C., Pagliuso, P.G., Hatton, P.D., (2010) Phys. Rev. B, 82, p. 104407. , PRBMDO 1098-0121 10.1103/PhysRevB.82.104407Fisk, Z., Remeika, J., Gschneider, K.A., Eyring, L., (1989) Handbook on the Physics and Chemistry of Rare Earths, p. 53. , edited by, Vol. 12 (Elsevier, AmsterdamJoshi, D.A., Nagalakshmi, R., Dhar, S.K., Thamizhavel, A., (2008) Phys. Rev. B, 77, p. 174420. , PRBMDO 1098-0121 10.1103/PhysRevB.77.174420Giles, C., Yokaichiya, F., Kycia, S., Sampaio, L., Ardiles-Saravia, D., Franco, M., Neuenschwander, R., (2003) J. Synchrotron Rad., 10, p. 430. , JSYRES 0909-0495 10.1107/S0909049503020958Vaillant, F., (1977) Acta Cryst. A, 33, p. 967. , ACACBN 0567-7394 10.1107/S0567739477002307Hill, J., McMorrow, D., (1996) Acta Cryst. A, 52, p. 236. , ACACEQ 0108-7673 10.1107/S0108767395012670Joly, Y., (2001) Phys. Rev. B, 63, p. 125120. , PRBMDO 1098-0121 10.1103/PhysRevB.63.125120Gibbs, D., Grubel, G., Harshman, D.R., Isaacs, E.D., McWhan, D.B., Mills, D., Vettier, C., (1991) Phys. Rev. B, 43, p. 5663. , PRBMDO 0163-1829 10.1103/PhysRevB.43.5663Collins, M.F., (1989) Magnetic Critical Scattering, , (Oxford University Press, Oxford)Wills, A., (2000) Physica B, p. 680. , PHYBE3 0921-4526 10.1016/S0921-4526(99)01722-6Detlefs, C., Islam, A.H.M.Z., Goldman, A.I., Stassis, C., Canfield, P.C., Hill, J.P., Gibbs, D., (1997) Phys. Rev. B, 55, pp. R680. , PRBMDO 0163-1829 10.1103/PhysRevB.55.R680Nandi, S., Su, Y., Xiao, Y., Price, S., Wang, X.F., Chen, X.H., Herrero-Martín, J., Brückel, Th., (2011) Phys. Rev. B, 84, p. 054419. , PRBMDO 1098-0121 10.1103/PhysRevB.84.054419Blundell, S., (2001) Magnetism in Condensed Matter, , Oxford Master Series in Condensed Matter Physics (Oxford University Press, Oxford)The density of states at the Fermi level for Gd 2 IrIn 8 was estimated using the electronic contribution to the heat capacity γ measured for the isomorphous reference compound La 2 IrIn 8Kovalev, O.V., Stokes, H.T., Hatch, D.M., (1993) Representations of the Crystallographic Space Groups, , 2nd ed., edited by (Gordon and Breach Science Publishers, Yverdon, Switzerland

Magnetic Properties of the RAuBi2 (R = Ce, Pr, Nd, Gd, Sm) Series of Intermetallic Compounds

AbstractIn this work we report the physical properties of the series of intermetallic compounds RAuBi2 (R = Ce, Pr, Nd, Gd, Sm) studied by means of x-ray powder diffraction, magnetic susceptibility, heat capacity and electrical resistivity measurements. These compounds were grown using the metallic Bi self-flux technique and they crystallize in a tetragonal ZrCuSi2 (P4/nmm) structure. Our RAuBi2 single crystals show an antiferromagnetic ordering TN ≥ 2.3K for all measured compounds. The values of TN show a dramatic breakdown of the De Gennes factor along this series

Heat capacity studies of Ce and Rh site substitution in the heavy fermion antiferromagnet CeRhIn_5;: Short-range magnetic interactions and non-Fermi-liquid behavior

In heavy fermion materials superconductivity tends to appear when long range magnetic order is suppressed by chemical doping or applying pressure. Here we report heat capacity measurements on diluted alloyes of the heavy fermion superconductor CeRhIn_5;. Heat capacity measurements have been performed on CeRh_{1-y}Ir_{y}In_5; (y <= 0.10) and Ce_{1-x}La_{x}Rh_{1-y}Ir_{y}In_5; (x <= 0.50) in applied fields up to 90 kOe to study the affect of doping and magnetic field on the magnetic ground state. The magnetic phase diagram of CeRh_{0.9}Ir_{0.1}In_5; is consistent with the magnetic structure of CeRhIn_5; being unchanged by Ir doping. Doping of Ir in small concentrations is shown to slightly increase the antiferromagnetic transition temperature T_{N} (T_{N}=3.8 K in the undoped sample). La doping which causes disorder on the Ce sublattice is shown to lower T_{N} with no long range order observed above 0.34 K for Ce_{0.50}La_{0.50}RhIn_5;. Measurements on Ce_{0.50}La_{0.50}RhIn_5; show a coexistence of short range magnetic order and non-Fermi-liquid behavior. This dual nature of the Ce 4f-electrons is very similar to the observed results on CeRhIn_5; when long range magnetic order is suppressed at high pressure.Comment: 8 pages, 9 figure

Unusual giant magnetostriction in the ferrimagnet Gd2/3_{2/3}Ca1/3_{1/3}MnO3_3

We report an unusual giant linear magnetostrictive effect in the ferrimagnet Gd$_{2/3}$Ca$_{1/3}$MnO$_3$ ($T_{c} \approx$80 K). Remarkably, the magnetostriction, negative at high temperature ($T \approx T_{c}$), becomes positive below 15 K when the magnetization of the Gd sublattice overcomes the magnetization of the Mn sublattice. A rather simple model where the magnetic energy competes against the elastic energy gives a good account of the observed results and confirms that Gd plays a crucial role in this unusual observation. Unlike previous works in manganites where only striction associated with 3$d$ Mn orbitals is considered, our results show that the lanthanide 4$f$ orbitals related striction can be very important too and it cannot be disregarded.Comment: 6 pages, 3 figure

Crystal Structure And Low Temperature Physical Properties Of Ho2 Co Ga8 Intermetallic Antiferromagnet

We have synthesized single crystalline samples of Ho2 Co Ga8 intermetallic compound using a Ga-flux method. This compound crystallizes with a tetragonal structure, space group P4mmm, and lattice parameters a=4.219 (5) Å and c=10.99 (2) Å. This structure is a bilayer version of the HoCo Ga5 (1-1-5) which hosts a series of heavy-fermion superconductors and complex antiferromagnetic intermetallic systems. Measurements of magnetic susceptibility, heat capacity, and electrical resistivity revealed that Ho2 Co Ga8 is a metallic Curie-Weiss paramagnet at high temperature and presents an antiferromagnetic ordering below TN ∼5 K. The low temperature magnetic properties of this compound show the effects of tetragonal crystalline electrical field and the Ruderman-Kittel-Kasuya-Yosid interactions and the results presented here are compared with a broader description of the evolution of the low- T magnetic properties of structurally related series of rare-earth based tetragonal 2-1-8 and 1-1-5 compounds. © 2008 American Institute of Physics.1037Continentino, M.A., V. Löhneysen, H., Rosch, A., Vojta, M., Wölfle, P., (2005) Braz. J. Phys., 35, p. 197. , 0103-9733 10.1590/S0103-97332005000100018, ();, Rev. Mod. Phys. 79, 1015 (2007)Thompson, J.D., Movshovich, R., Fisk, Z., Bouquet, F., Curro, N.J., Fisher, R.A., Hammel, P.C., Sarrao, J.L., (2001) J. Magn. Magn. Mater., 226-230, p. 5. , and references thereinPagliuso, P.G., Movshovich, R., Bianchi, A.D., Nicklas, M., Moreno, N.O., Thompson, J.D., Hundley, M.F., Fisk, Z., (2002) Physica B, 312-313, p. 129Moreno, N.O., Hundley, M.F., Pagliuso, P.G., Movshovich, R., Nicklas, M., Thompson, J.D., Sarrao, J.L., Fisk, Z., (2002) Physica B, 312-313, p. 274Bianchi, A., Movshovich, R., Vekhter, I., Pagliuso, P.G., Sarrao, J.L., (2003) Phys. Rev. Lett., 91, p. 257001Sarrao, J.L., Morales, L.A., Thompson, J.D., Scott, B.L., Stewart, G.R., Wastin, F., Rebizant, J., Lander, G.H., (2002) Nature (London), 420, p. 297Bauer, E.D., Thompson, J.D., Sarrao, J.L., Morales, L.A., Wastin, F., Rebizant, J., Griveau, J.C., Stewart, G.R., (2004) Phys. Rev. Lett., 93, p. 147005Pagliuso, P.G., Garcia, D.J., Miranda, E., Granado, E., Lora-Serrano, R., Giles, C., Duque, J.G.S., Rettori, C., (2006) J. Appl. Phys., 99, pp. 08P703. , and references thereinGranado, E., Uchoa, B., Malachias, A., Lora-Serrano, R., Pagliuso, P.G., Westfahl Jr., H., (2006) Phys. Rev. B, 74, p. 214428Lora-Serrano, R., Giles, C., Granado, E., Garcia, D.J., Miranda, E., Agüero, O., Mendoņa Ferreira, L., Pagliuso, P.G., (2006) Phys. Rev. B, 74, p. 214404Hieu, N.V., Shishido, H., Nakashima, H., Sugiyama, K., Settai, R., Takeuchi, T., Matsuda, T.D., Nuki, Y., (2007) J. Magn. Magn. Mater., 310, p. 1721Hudis, J., Hu, R., Broholm, C.L., Mitrovic, V.F., Petrovic, C., (2006) J. Magn. Magn. Mater., 307, p. 301Yokaichiya, F., Giles, C., (2004) Physica B, 345, p. 82Yu, G., Yarmolyuk, Ya.P., Gladyshevskii, E.I., (1979) Kristallografiya, 24, p. 242Bao, W., Pagliuso, P.G., Sarrao, J.L., Thompson, J.D., Fisk, Z., (2001) Phys. Rev. B, 64, p. 020401. , (R)Adriano, C., Lora-Serrano, R., Giles, C., De Bergevin, F., Lang, J.C., Srajer, G., Mazzoli, C., Pagliuso, P.G., (2007) Phys. Rev. B, 76, p. 104515Amara, M., Gaĺra, R.M., Morin, P., Voiron, J., Burlet, P., (1995) J. Magn. Magn. Mater., 140-144, p. 1157Kletowski, Z., Slawinski, P., (1990) Solid State Commun., 76, p. 867Czopnik, A., (1995) Phys. Status Solidi A, 147, p. 3

Hierarchical Mean-Field Theories in Quantum Statistical Mechanics

We present a theoretical framework and a calculational scheme to study the coexistence and competition of thermodynamic phases in quantum statistical mechanics. The crux of the method is the realization that the microscopic Hamiltonian, modeling the system, can always be written in a hierarchical operator language that unveils all symmetry generators of the problem and, thus, possible thermodynamic phases. In general one cannot compute the thermodynamic or zero-temperature properties exactly and an approximate scheme named ``hierarchical mean-field approach'' is introduced. This approach treats all possible competing orders on an equal footing. We illustrate the methodology by determining the phase diagram and quantum critical point of a bosonic lattice model which displays coexistence and competition between antiferromagnetism and superfluidity.Comment: 4 pages, 2 psfigures. submitted Phys. Rev.