Anisotropic Magnetocaloric Effect In Erga2 And Hoga2 Single-crystals

In this work we study the anisotropic magnetocaloric properties of ErGa2 and HoGa2 single-crystals. Both compounds present antiferromagnetic ordering below 10 K but with different easy axis as a result of the crystal field anisotropy. The single-crystal conventional MCE values are similar or in certain circumstances even larger than the results for the polycrystalline material. The anisotropic MCE was calculated by taking the difference of the entropy change of the easy and hard magnetization directions. For both compounds, the anisotropic variation of entropy is as large as the conventional entropy change obtained by sweeping the magnetic field up to 5 T. Particularly for ErGa2 an inverse MCE for a 3 T field oriented along the easy axis is obtained with similar magnitude of the 5 T MCE found for polycrystalline samples. The results show that by exploring anisotropic properties of the materials it is possible to obtain a significant MCE. From a technological point of view this can be an interesting alternative because the MCE is produced just by rotating the magnetic material under a constant magnetic field. © 2013 Elsevier B.V. All rights reserved.582461465Tishin, M.A., (1999) Els. Sci. B, 12, pp. 395-520Yu, B.F., Gao, Q., Zhang, B., Meng, X.Z., Chenk, Z., (2003) Int. J. Refrig, 26, p. 622Gschneidner Jr., K.A., Pecharsky, V.K., Tsokol, A.O., (2005) Rep. Prog. Phys, 68, p. 1479Giguère, A., Foldeaki, M., Ravi Gopal, B., Chahine, R., Bose, T.K., Frydman, A., Barclay, J.A., (1999) Phys. Rev. Lett, 83, p. 2262Pecharsky, V., Gschneider Jr., K., (1997) Phys. Rev. Lett, 78, p. 4494Tegus, O., Bruck, E., Buschow, K.H.J., De Boer, F.R., (2002) Nature, 415, p. 150Wada, H., Taniguchi, K., Tanabe, Y., (2002) Mater. Trans, 43, p. 73De Campos, A., Rocco, D.L., Carvalho, A.M.G., Caron, L., Coelho, A.A., Gama, S., Da Silva, L.M., De Oliveira, N.A., (2006) Nat. Mater, 5, p. 802Kuzmin, M.D., Tishin, A.M., (1993) J. Appl. Phys, 73, p. 4083Lima, A.L., Gschneidner Jr., K.A., Pecharsky, V.K., (2004) J. Appl. Phys, 96, p. 2164Von Ranke, P.J., De Oliveira, N.A., Plaza, E.J.R., De Sousa, V.S.R., Alho, B.P., Magnus, A., Carvalho, G., Reis, M.S., (2008) J. Appl. Phys, 104, p. 093906Plaza, E.J.R., De Sousa, V.S.R., Alho, B.P., Von Ranke, P.J., (2010) J. Alloys Comp, 503, pp. 277-280Nikitin, S.A., Skokov, K.P., Koshkid'ko, Yu.S., Pastushenkov, Yu.G., Ivanova, T.I., (2010) Phys. Rev. Lett, 105, p. 137205Dos Reis, R.D., Da Silva, L.M., Dos Santos, A.O., Medina, A.M.N., Cardoso, L.P., Gandra, F.G., (2010) J. Phys.: Condens. Matter, 22, p. 486002Andreev, A.V., Baranov, N.V., Markin, P.E., Aruga Katori, H., Goto, T., Nakotte, H., Radwafiski, R.J., Kim-Ngan, N.H., (1995) J. Magn. Magn. Mat, 140-144, p. 1123Doukouré, M., Gignoux, D., (1982) J. Magn. Magn. Mater, 30, p. 111Von Ranke, P.J., De Oliveira, N.A., Alho, B.P., Plaza, E.J.R., De Sousa, V.S.R., Caron, L., Reis, M.S., (2009) J. Phys.: Condens. Matter, 21, p. 056004Von Ranke, P.J., Alho, B.P., Nobrega, E.P., Ade Oliveira, N., (2009) Physica B, 404, p. 3045Samanta, T., Das, I., Banerjee, S., (2007) Appl. Phys. Lett, 91, p. 152506Gomes, A.M., Garcua, F., Guimarães, A.P., Reis, M.S., Amaral, V.S., (2004) Appl. Phys. Lett, 85 (21), p. 4974Gignoux, D., Schmitt, D., Zhang, F.Y., (1996) J Alloys Comp, 234, p. 239Zou, M., Mudryk, Ya., Pecharsky, V.K., Gschneidner, K.A., Schlagel, D.L., Lograsso, T.A., (2007) Phys. Rev. B, 75 (2), p. 02441

A General Approach To First Order Phase Transitions And The Anomalous Behavior Of Coexisting Phases In The Magnetic Case

First order phase transitions for materials with exotic properties are usually believed to happen at fixed values of the intensive parameters (such as pressure, temperature, etc.) characterizing their properties.. It is also considered that the extensive properties of the phases (such as entropy, volume, etc.) have discontinuities at the transition point, but that for each phase the intensive parameters remain constant during the transition. These features are a hallmark for systems described by two thermodynamic degrees of freedom. In this work it is shown that first order phase transitions must be understood in the broader framework of thermodynamic systems described by three or more degrees of freedom. This means that the transitions occur along intervals of the intensive parameters, that the properties of the phases coexisting during the transition may show peculiar behaviors characteristic of each system, and that a generalized Clausius-Clapeyron equation must be obeyed, These features for the magnetic case are confirmed, and it is shown that experimental caforimetric data agree well with the magnetic Clausius-Clapeyron equation for MnAs. An estimate for the point in the temperature-field plane where the first order magnetic transition turns to a second order one is obtained (the critical parameters) for MnAs and Gd5Ce2Si2 compounds. Anomalous behavior of the volumes of the coexisting phases during the magnetic first order transition is measured, and it is shown that the anomalies for the individual phases are hidden in the behavior of the global properties as the volume. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA.196942949Zeldov, E., Majer, D., Konczykowski, M., Ceshkenbein, V.B., Vinokur, V.M., Shtrikman, H., (1995) Nature, 375, p. 373Soibel, A., Zeldov, E., Rappaport, M., Myasoedov, Y., Tamegai, T., Ooi, S., Konczykowski, M., Ceshkenbein, V.B., (2000) Nature, 406, p. 282Littlewood, P., (1999) Nature, 399, p. 529Ahn, K.H., Lookman, T., Bishop, A.R., (2004) Nature, 428, p. 401Ren, Y., Palstra, T.T.M., Khomskii, D.I., Pellagrin, E., Nugroh, A.A., Menovsky, A.A., Savatzky, C.A., (1998) Nature, 396, p. 441Y. Ren, T. T. M. Palstra, D. I. Khomskii, E. Pellagrin, A. A. Nugroho, A. A. Menovsky, G. A, Savatzky, Phys. Rev. B 2000, 62, 6577Fleming, R.M., DiSalvo, F.J., Cava, R.J., Waszczak, J.V., Phys. Rev. B, 981 (5), p. 2850. , 24Okada, K., Koyama, K., Hedo, M., Uwatoko, Y., Watanabe, K., (2008) Phys. B, 403, p. 1612A, Crisanti, L. Leuzzi, Phys. Rev. Lett. 002, 89, 23, 237204V. K. Pecharsky, K. A. Gschneidner, Jr, Phys. Rev. Lett. 1997. 78, 23, 4494Wada, H., Tanabe, Y., (2001) Appl. Phys. Lett, 79 (20), p. 3302Wada, H., Taniguchi, K., Tanabe, Y., (2002) Mater. Trans, 43 (1), p. 73Tegus, O., Brück, E., Buschow, K.H.J., de Boer, F.R., (2002) Nature, 415, p. 150Fujita, A., Fujieda, S., Hasegawa, Y., Fukamichi, K., (2003) Phys. Rev. B, 67, p. 104416Annaorazov, M.P., Nikitin, S.A., Tyurin, A.L., Asatryan, K.A., Dovletov, A.K., (1996) J. Appl. Phys, 79 (3), p. 1689Gschneidner Jr, K.A., Pecharsky, V.K., Tsokol, A.O., (2005) Rep. Prog. Phys, 68, p. 1479Brück, E., (2005) J. Phys. D, 38, pp. R381Cama, S., Coelho, A.A., de Campos, A., Carvalho, A.M.G., Gandra, F.C.G., von Ranke, P.J., de Oliveira, N.A., (2004) Phys. Rev. Lett, 93 (23), p. 237202de Campos, A., Rocco, D.L., Carvalho, A.M.G., Caron, L., Coelho, A.A., Gama, S., da Silva, L.M., de Oliveira, N.A., (2006) Not Mater, 5, p. 802Rocco, D.L., de Campos, A., Carvalho, A.M.G., Caron, L., Coelho, A.A., Gama, S., Gandra, F.C.G., de Oliveira, N.A., (2007) Appl. Phys. Lett, 90 (4), p. 1Tishin, A.M., Spichkin, I., (2003) The Magnetocaloric Effect and Its Applications, , IOP, Bristol, UKIdo, H., Yasuda, S., Kido, M., Kido, G., Miyakawa, T., Special supplement 12 on Colloque C8 (1988) J. Phys, 49, p. 167Wada, H., Asano, T., (2008) J. Magn. Magn. Mater, 290-291, p. 703Selte, K., Kjekshus, A., Andresen, A.F., (1974) Acta Chem. Scand. A, 28, p. 61Selte, K., Kjekshus, A., Valde, G., Andresen, A.F., (1976) Acta Chem. Scand. A, 30, p. 8Selte, K., Kjekshus, A., Valde, G., Andresen, A.F., (1976) Acta Chem. Scand. A, 30, p. 468Selte, K., Kjekshus, A., Andresen, A.F., Zieba, A., (1977) J. Phys. Chem, Solids, 38, p. 719Zieba, A., Zach, R., Fjellvåg, H., Kjekshus, A., (1987) J. Phys. Chem. Solids, 48, p. 79Callen, H.B., (1985) Thermodynamics and an Introduction to Thermostatistics, , 2nd ed. Wiley, New YorkBinder, I., (1987) Rep. Prog. Phys, 50, p. 783V. K. Pecharsky, K. A. Gschneidner, jr., A. O. Pecharsky, A. M. Tishin, Phys. Rev. B 2001, 64, 144406Spichkin, Y.I., Tishin, A.M., (2005) J. Magn. Magn. Mater, 290-291, p. 700Gschneidner Jr, K.A., Pecharsky, V.K., (1997) Phys. Rev. Lett, 78 (22), p. 4281Levin, E.M., Pecharsky, V.K., Gschneidner Jr, K.A., Tomlinson, P., (2000) J. Magn. Magn. Mater, 210, p. 181Mira, J., Rivadulla, F., Rivas, J., Fondado, A., Guidi, T., Caciuffo, R., Carsughi, F., Goodenough, J.B., (2003) Phys. Rev. Lett, 90 (9), p. 097203Ishikawa, F., Koyama, K., Watanabe, K., Wada, H., (2004) Phys. B, 346-347, p. 408Avdeev, M., Jorgensen, J.D., Short, S., Samara, G.A., Venturini, E.L., Yang, P., Morosin, B., (2006) Phys. Rev. B, 73, pp. 064105-64111Imry, Y., Wortis, M., (1979) Phys. Rev. B, 19 (7), p. 3580Prince, A., (1966) Alloy Phase Equilibria, p. 21. , Elsevier, AmsterdamChoe, W., Pecharsky, V.K., Pecharsky, A.O., Gschneidner Jr, K.A., Young Jr, V.G., Miller, G.J., (2000) Phys. Rev. Lett, 84 (20), p. 4617Tocado, L., Palacios, E., Buriel, R., (2006) J. Therm. Anal. Calorim, 84 (1), p. 213Toby, B.H., (2001) J. Appl. Crystallogr, 34, p. 210A. P. Hammersley, FIT2D V9.129 Reference Manual V 3.1, ESRF (European Synchrotron Radiation Facility) Internal Report, ESRF98HA01T, 1998A. C. Larson, R. B. von Dreele, General Structure Analysis System (GSAS), Los Alamos National Laboratory Report LAUR 86-748, i200