Percolation Processes And Spin-reorientation Of Prni5-xco X

In the present work we report on the structural and magnetic behaviors of the PrNi5-xCox intermetallic compounds. Due to the competition between the anisotropy energies of both Co and Pr sublattices, this series has a spin-reorientation phenomenon at low temperature (140 K). The Curie temperature, as a function of Co content, has a sudden increase above a critical concentration xc ∼1.9 and this feature is assigned as a percolation of geometrically spaced Co clusters. This assumption is explained based on the critical exponent of percolation theory. The series presents therefore a rich magnetic phase diagram, which could be established over a full doping range, i.e., from x=0 to x=5. We have also studied these compounds on the magnetocaloric point of view and found a quite large full width at half maximum (δ TFWHM) of the magnetic entropy change curves for some of the compositions, due to the merging of the ΔS peaks associated with the spin-reorientation process and the Curie temperature TC. In addition, the series has an appreciable relative cooling power, which is therefore suitable to be used in a magnetic refrigerator operating in a large range of temperature. © 2009 The American Physical Society.791Wallace, W., Craig, R., Gupta, H., Hirosawa, S., Pedziwiatr, A., Oswald, E., Schwab, E., (1984) IEEE Trans. Magn., 20, p. 1599. , 10.1109/TMAG.1984.1063241Velu, E.M.T., Obermyer, R.T., Sankar, S.G., Wallace, W.E., (1989) IEEE Trans. Magn., 25, p. 3779. , 10.1109/20.42431Von Ranke, P.J., Pecharsky, V.K., Gschneidner, K.A., Korte, B.J., (1998) Phys. Rev. B, 58, p. 14436. , 10.1103/PhysRevB.58.14436Ermolenko, A.S., Rozhda, A.F., (1977) IEEE Trans. Magn., 13, p. 1339. , 10.1109/TMAG.1977.1059573Chuang, Y.C., Wu, C.H., Chang, S.C., Li, T.C., (1984) J. Less Common Met., 97, p. 245. , 10.1016/0022-5088(84)90029-8Andreyev, A.V., Deryagin, A.V., Zadvorkin, S.M., (1985) Phys. Met. Metallogr., 60, p. 96Van Mal, H.H., Buschow, K.H.J., Kuijpers, F.A., (1973) J. Less Common Met., 32, p. 289. , 10.1016/0022-5088(73)90095-7Ermolenko, A.S., (1979) IEEE Trans. Magn., 15, p. 1765. , 10.1109/TMAG.1979.1060377Von Ranke, P.J., Mota, M.A., Grangeia, D.F., Carvalho, A.M.G., Gandra, F.C.G., Coelho, A.A., Caldas, A., Gama, S., (2004) Phys. Rev. B, 70, p. 134428. , 10.1103/PhysRevB.70.134428Chuang, Y.C., Wu, C.H., Chang, Y.C., (1982) J. Less Common Met., 84, p. 201. , 10.1016/0022-5088(82)90145-XCoroian, N., Klosek, V., Isnard, O., (2007) J. Alloys Compd., 427, p. 5. , 10.1016/j.jallcom.2006.02.061Ibarra, M.R., Morellon, L., Algarabel, P.A., Moze, O., (1991) Phys. Rev. B, 44, p. 9368. , 10.1103/PhysRevB.44.9368Stauffer, D., Aharony, A., (1992) Introduction to Percolation Theory, , Taylor and Francis, LondonLopes, A.M.L., Araújo, J.P., Ramasco, J.J., Rita, E., Amaral, V.S., Correia, J.G., Suryanarayanan, R., (2006) Phys. Rev. B, 73, p. 100408. , 10.1103/PhysRevB.73.100408Zlotea, C., Isnard, O., (2002) J. Alloys Compd., 346, p. 29. , 10.1016/S0925-8388(02)00500-5Buschow, K.H.J., Brouha, M., (1976) J. Appl. Phys., 47, p. 1653. , 10.1063/1.322787Fahnle, M., Oesterreicher, H., (1984) Phys. Rev. B, 29, p. 2793. , 10.1103/PhysRevB.29.2793Fahnle, M., Oesterreicher, H., (1983) Phys. Rev. B, 27, p. 5586. , 10.1103/PhysRevB.27.5586Bray, A.J., (1987) Phys. Rev. Lett., 59, p. 586. , 10.1103/PhysRevLett.59.586Salamon, M.B., Lin, P., Chun, S.H., (2002) Phys. Rev. Lett., 88, p. 197203. , 10.1103/PhysRevLett.88.197203Magen, C., Algarabel, P.A., Morellon, L., Araujo, J.P., Ritter, C., Ibarra, M.R., Pereira, A.M., Sousa, J.B., (2006) Phys. Rev. Lett., 96, p. 167201. , 10.1103/PhysRevLett.96.167201Pecharsky, V.K., Gschneidner, K.A., (1999) J. Appl. Phys., 86, p. 565. , 10.1063/1.370767Gschneidner, K.A., Pecharsky, V.K., (2000) Annu. Rev. Mater. Sci., 30, p. 387. , 10.1146/annurev.matsci.30.1.38