Presence of a paramagnetic phase well below the ferromagnetic onset in La _{0.67 − x} Bi _x Ca _0.33 MnO ₃

Abstract

Partial replacement of La by Bi in La0.67Ca0.33MnO3 depresses the ferromagnetic order of the compound and leads to a stepwise magnetic behavior characterized by two subsequent transitions at ∼ 120 K and ∼ 225 K. Based on a combined study of the electron spin resonance spectra and the thermal and isothermal magnetization, a complete scenario for the phase separation that causes the complex behavior has been given. It is found that the paramagnetic phase exists in a wide temperature region even below the ferromagnetic onset at ∼ 225 K. It coexists with the ferromagnetic phase below ∼ 240 K and with both the ferromagnetic and antiferromagnetic phases below ∼ 190 K with a reduced but significant fraction. The magnetization jump at ∼ 120 K is possibly a conversion of the remaining paramagnetic phase into the ferromagnetic phase.

Magnetoresistance and hysteresis phenomena of (La0.75Bi0.25)0.67Ca0.33MnO3

“…2(a) and (b). The hysteresis behavior of the Bi-doped La 0.67 Ca 0.33 MnO 3 system due to the CO state was investigated by Sun et al [10][11][12].…”

Symmetry in Many-Body Physics

“…We need to solve the system of equations for the order parameter s 1 , given in (64) and satisfying condition (55), for the order parameter s 2 , given in (66) and satisfying condition (56), and for the probability of ferromagnetic phase w, defined in (73) and satisfying conditions (28). If there occur several solutions, it is necessary to choose the solution that corresponds to the minimal free energy and satisfies the stability conditions (74).…”

“…The coexistence of ferromagnetic and nonmagnetic phases was also observed in Y 2 Co 7 , YCo 3 , Co(S x Se 1−x ) 2 , Co(Ti x Al 1−x ) 2 , and Lu(Co 1−x Al x ) 2 [59,60]. In colossal magnetoresistance materials, such as La 1−x Ca x MnO 3 and La 1−x Sr x CoO 3 , one observes the coexistence of a paramagnetic insulating, or semiconducting, phase and a ferromagnetic metallic phase [61][62][63], while in La 0.67−x Bi x Ca 0.33 MnO 3 , paramagnetic and antiferromagnetic phases coexist [64]. Nanoscale phase separation into ferromagnetic and paramagnetic regions has been observed in the colossal magnetoresistence compound, EuB 5.99 C 0.01 [65].…”