Specific heat at low temperatures and magnetic measurements inNd0.5Sr0.5MnO

Abstract

We studied the magnetization as a function of temperature and magnetic field in the compounds Nd 0.

Analysis of low temperature specific heat in Nd0.5Sr0.5MnO3 and R0.5Ca0.5MnO3 (R=Nd, Sm, Dy and Ho) compounds

“…Consequently, in a doped system like Nd 1Àx (Ca,Sr) x MnO 3 as compared with La 1Àx (Ca,Sr) x MnO 3 , a closer competition with generic instabilities, such as antiferromagnetic superexchange, orbital and charge ordering, would exist between the electron-phonon, electron-electron and double-exchange interactions [7]. The high values of specific heat are observed at low temperature for Nd 0.5 Sr 0.5 MnO 3 , Nd 0.5 Ca 0.5 MnO 3 , Sm 0.5 Ca 0.5 MnO 3 , Dy 0.5 Ca 0.5 MnO 3 and Ho 0.5 Ca 0.5 MnO 3 compounds which indicates enhanced excitations and could be due to an increase in the effective mass of the electrons caused by localization [2]. Nd 0.5 Sr 0.5 MnO 3 shows a ferromagnetic transition at T C E250 K and an antiferromagnetic transition at T N E160 K. The Nd 0.5 Ca 0.5 MnO 3 compound presented a strong maximum near T CO , but showed an unexpected minimum close to the antiferromagnetic transition temperature T N E160 K. Usually an antiferromagnetic transition is accompanied by a maximum in the temperature dependence of the magnetization.…”

“…The existence of charge ordering in Dy 0.5 Ca 0.5 MnO 3 and Ho 0.5 Ca 0.5 MnO 3 was suggested by Terai et al [10]. Charge ordering transition temperatures (T CO ) for Nd 0.5 Sr 0.5 MnO 3 , Nd 0.5 Ca 0.5 MnO 3 , Sm 0.5 Ca 0.5 MnO 3 , Dy 0.5 Ca 0.5 MnO 3 and Ho 0.5 Ca 0.5 MnO 3 are 160, 250, 270, 280 and 271 K, respectively [2,[8][9][10][11].…”

“…The physical properties in manganese perovskites are thought to arise from the strong competition among a ferromagnetic double-exchange interaction, an antiferromagnetic superexchange interaction and the spin-phonon coupling. These interactions are determined by intrinsic parameters such as doping level, average cationic size, cationic disorder and oxygen stoichiometry [2]. The striking phenomena are related to a strong interplay of charge, spin, orbital and lattice degrees of freedom.…”

Electrical and magnetic properties of Y-doped La0.5Sr0.5MnO3 manganite system: Observation of step-like magnetization

“…Especially, for the half-doped R 0.5 A 0.5 MnO 3 compounds [3][4][5][6][7][8][9][10], generally with relatively small ionic radii, hr A i, shows interesting CE-type antiferromagnetic (AFM) structure [11]. Both ferromagnetic (FM) and AFM interactions sometimes appear simultaneously in these compounds, respectively, due to double exchange (DE) and super-exchange (SE) interactions among Mn ions.…”

Analysis of Thermodynamic and Phononic Properties of Perovskite Manganites

“…At the international level, an extensive research work is being conducted by several groups (Alonso et al, 2000;Lo´pez et al, 2002;Ku et al, 2004;Kimura et al, 2005;Iliev et al, 2006;Tachibana et al, 2007;) …”