Theoretical Investigation On The Existence Of Inverse And Direct Magnetocaloric Effect In Perovskite Euzro 3

We report on the magnetic and magnetocaloric effect calculations in antiferromagnetic perovskite-type EuZrO 3. The theoretical investigation was carried out using a model Hamiltonian including the exchange interactions between nearest-neighbor and next-nearest-neighbor for the antiferromagnetic ideal G-type structure (the tolerance factor for EuZrO 3 is t = 0.983, which characterizes a small deformation from an ideal cubic perovskite). The molecular field approximation and Monte Carlo simulation were considered and compared. The calculated magnetic susceptibility is in good agreement with the available experimental data. For a magnetic field change from zero to 2 T a normal magnetocaloric effect was calculated and for a magnetic field change from zero to 1 T, an inverse magnetocaloric effect was predicted to occur below T = 3.6 K. © 2011 American Institute of Physics.1098Warburg, E., (1881) Ann. Phys., 13, p. 141. , 10.1002/andv249:5Pecharsky, V.K., Gschneidner Jr., K.A., (1997) Phys. Rev. Lett., 78, p. 4494. , 10.1103/PhysRevLett.78.4494Von Ranke, P.J., De Oliveira, N.A., Gama, S., (2004) J. Magn. Magn. Mater., 277, p. 78. , 10.1016/j.jmmm.2003.10.013De Oliveira, N.A., Von Ranke, P.J., (2008) Phys. Rev. B, 77, p. 214439. , 10.1103/PhysRevB.77.214439Von 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. 093906. , 10.1063/1.3009974Sande, P., Hueso, L.E., Miguens, D.R., Rivas, J., Rivadulla, F., Lopez-Quintela, M.A., (2001) Appl. Phys. Lett., 79, p. 2040. , 10.1063/1.1403317Yamada, H., Goto, T., (2004) Physica B, 346-347, p. 104. , 10.1016/j.physb.2004.01.029Nobrega, E.P., De Oliveira, N.A., Von Ranke, P.J., Troper, A., (2006) Phys. Rev. B, 74, p. 144429. , 10.1103/PhysRevB.74.144429Tishin, A.M., Spichkin, Y.I., (2003) The Magnetocaloric Effect and Its Applications, , 1st ed. (Institute of Physics, Bristol)De Oliveira, N.A., Von Ranke, P.J., (2010) Phys. Rep., 489, p. 89. , 10.1016/j.physre2009.12.006Sasaki, S., Prewitt, C.T., Liebermann, R.C., (1983) Am. Mineral., 68, p. 1189Kuz'Min, M.D., Tishin, A.M., (1991) J. Phys. D: Appl. Phys., 24, p. 2039. , 10.1088/0022-3727/24/11/020Kimura, H., Numazawa, T., Sato, M., Ikeya, T., Fukuda, T., (1995) J. Appl. Phys., 77, p. 432. , 10.1063/1.359349Phan, M.-H., Yu, S.-C., Review of the magnetocaloric effect in manganite materials (2007) Journal of Magnetism and Magnetic Materials, 308 (2), pp. 325-340. , DOI 10.1016/j.jmmm.2006.07.025, PII S0304885306009577Zong, Y., Fujita, K., Akamatsu, H., Murai, S., Tanaka, K., (2010) J. Solid State Chem., 183, p. 168. , 10.1016/j.jssc.2009.10.014Kolodiazhnyi, T., Fujita, K., Wang, L., Zong, Y., Tanaka, K., Sakka, Y., Takayama-Muromachi, E., (2010) Appl. Phys. Lett., 96, p. 252901. , 10.1063/1.3456730Greedan, J.E., Chien, C.-L., Johnston, R.G., (1976) J. Solid State Chem., 19, p. 155. , 10.1016/0022-4596(76)90163-8Nobrega, E.P., De Oliveira, N.A., Von Ranke, P.J., Troper, A., Monte Carlo calculations of the magnetocaloric effect in Gd5(SixGe1-x)4 compounds (2005) Physical Review B - Condensed Matter and Materials Physics, 72 (13), pp. 1-7. , http://oai.aps.org/oai/?verb=ListRecords&metadataPrefix= oai_apsmeta_2&set=journal:PRB:72, DOI 10.1103/PhysRevB.72.134426, 134426Nbrega, E.P., De Oliveira, N.A., Von Ranke, P.J., Troper, A., (2008) J. Magn. Magn. Mater., 320, p. 147. , 10.1016/j.jmmm.2008.02.036Landau, D.P., Binder, K., (2000) A Guide to Monte Carlo Simulations in Statistical Physics, , (Cambridge University Press, Cambridge)Yang, H., Ohishi, Y., Kurosaki, K., Muta, H., Yamanaka, S., (2010) J. Alloys Compd., 504, p. 201. , 10.1016/j.jallcom.2010.05.088Terki, R., Bertrand, G., Aourag, H., Coddet, C., Thermal properties of Ba 1-xSr xZrO 3 compounds from microscopic theory (2008) Journal of Alloys and Compounds, 456 (1-2), pp. 508-513. , DOI 10.1016/j.jallcom.2007.02.133, PII S0925838807005397Bagayoko, D., Zhao, G.L., Fan, J.D., Wang, J.T., (1998) J. Phys. Condens. Matter, 10, p. 5645. , 10.1088/0953-8984/10/25/014Von Ranke, P.J., Mota, M.A., Grangeia, D.F., Carvalho, A.M.G., Gandra, F.C.G., Coelho, A.A., Caldas, A., Gama, S., Magnetocaloric effect in the RNi 5 (R = Pr, Nd, Gd, Tb, Dy, Ho, Er) series (2004) Physical Review B - Condensed Matter and Materials Physics, 70 (13), pp. 1344281-1344286. , DOI 10.1103/PhysRevB.70.134428, 13442

Fermions in three-dimensional spinfoam quantum gravity

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Based on the q-deformed oscillator algebra, we study the behavior of the mean occupation number and its analogies with intermediate statistics and we obtain an expression in terms of an infinite continued fraction, thus clarifying successive approximations. In this framework, we study the thermostatistics of q-deformed bosons and fermions and show that thermodynamics can be built on the formalism of q-calculus. The entire structure of thermodynamics is preserved if ordinary derivatives are replaced by the use of an appropriate Jackson derivative and q-integral. Moreover, we derive the most important thermodynamic functions and we study the q-boson and q-fermion ideal gas in the thermodynamic limit.Comment: 14 pages, 2 figure

Stability and collapse of localized solutions of the controlled three-dimensional Gross-Pitaevskii equation

On the basis of recent investigations, a newly developed analytical procedure is used for constructing a wide class of localized solutions of the controlled three-dimensional (3D) Gross-Pitaevskii equation (GPE) that governs the dynamics of Bose-Einstein condensates (BECs). The controlled 3D GPE is decomposed into a two-dimensional (2D) linear Schr\"{o}dinger equation and a one-dimensional (1D) nonlinear Schr\"{o}dinger equation, constrained by a variational condition for the controlling potential. Then, the above class of localized solutions are constructed as the product of the solutions of the transverse and longitudinal equations. On the basis of these exact 3D analytical solutions, a stability analysis is carried out, focusing our attention on the physical conditions for having collapsing or non-collapsing solutions.Comment: 21 pages, 14 figure