Magnetic properties of Bi-doped [formula omitted

Abstract

Structure and magnetic properties of the La 0.5− x Bi x Ca 0.5MnO 3 ( x = 0 , 1/16, 1/8, 1/4, 3/8 and 1/2) system have been experimentally investigated. The substitution of Bi 3+ ion for La 3+ ion systematically enhances the charge-ordering (CO) temperature. Electron spin resonance (ESR) and isothermal magnetization measurements reveal the coexistence of ferromagnetic (FM), antiferromagnetic (AFM) domains and paramagnetic (PM) matrix below T C O in 0 ≤ x ≤ 3 / 8 . Kinetic hindrance to the first order charge ordering transition plays an important role in this coexisting phases. Such a coexistence of PM, FM and AFM domains leads to a compressive strain effect, resulting in a counterclockwise thermal hysteresis in M ( T ) curves. The hysteresis weakens with increasing Bi content, suggesting that the inner compressive strain becomes increasingly weaker. For x = 1 / 2 , only AFM state coexist with PM matrix below T C O and FM state only coexists with AFM state below ∼50 K. Therefore, almost no thermal hysteresis in M ( T ) curves is observed around T C O for x = 1 / 2 .