Structure, Magnetoresistance and Magnetism of La[sub 0.67](Sr[sub 1−x]Ba[sub x])[sub 0.33]MnO[sub 3] Perovskite

Abstract

The effect of Ba-substitution at Sr site on the structure, magnetoresistance and magnetic properties of Lao 67(Sri.,;BaJo.33Mn03 samples with x = 0.00, 0.25, 0.50, 0.75 and 1.00 has been investigated. Single phase samples were obtained by a conventional solid state reaction method with rhombohedral (x = 0.00) and orthorombic (x = 1.00) structure. The grain size increases with Ba content. Low field magnetoresistance phenomenon at low temperature can be observed for all samples. However it vanishes at 300 K for x = 0.75 and 1.00. The variation of MR% value is small ranging between 16 to 18% at 100 K in an applied field of 1 T. All samples show a single magnetic transition from the ferromagnetic (FM) state to the paramagnetic (PM) state as the temperature increases. Curie temperature, Tc decrease with increasing Ba concentration.

Tunable Curie Temperature and Magnetocaloric Effect in Mg-Doped (La, Sr)MnO₃ Manganites

“…The values of T C , which correspond to the minimum of magnetization derivative with respect to temperature, are estimated to be 354 K, 182 K, 129 K and 97 K for x = 0, 0.05, 0.15 and 0.2, respectively. According to the double exchange model, the overlap between Mn(3d) and O(2p) is weakened by the reduced bond angle, which in turn reduces the exchange coupling between Mn 3+ and Mn 4+ , resulting in the decrease of T C [12]. Similar phenomenon has been observed in the Co-doped manganites [16].…”

“…The substitution of Ca for Sr resulted in a decrease of T C Corresponding authors: X. F. Zhang (e-mail: xuefeng056@163.com) and an enhancement of MCE [11]. It was pointed out by Zalita et al that the crystalline structure was modified from rhombohedral for x = 0 to orthorhombic for x = 0.33 when Sr was completely replaced by Ba in La 0.67 Sr 0.33-x Ba x MnO 3 [12]. Reddy et al [13] and Kameli et al [14] investigated the magnetic and electrical properties of Mg-doped (La,Sr,Mg)MnO 3 and found that the paramagneticferromagnetic and metal-insulator transition temperatures decreased with increasing Mg concentration.…”

Structural, magnetic, dielectric and magneto-dielectric coupling analysis of ferromagnetic-PbZr0.52Ti0.48O3 nanocomposites

“…The dielectric constant of LSMO-PZT system increase with increase in content of PZT, as shown in Fig. 3a and the achieved [25,26]. The dielectric loss (tan d) values decrease as frequency increases up to 500 Hz and become more or less constant up to 1 MHz for all nanocomposites, as shown in Fig.…”