Spin-glass-like properties ofLa0.8Ca0.2MnO3nanoparticles ensembles

Abstract

Magnetic properties of compacted La 0.8 Ca 0.2 MnO 3 manganite nanoparticles with average particle size of 18 and 70 nm and Curie temperatures T C Ϸ 231 K and T C Ϸ 261 K, respectively, have been investigated. The relative volume of the ferromagnetic phase has been estimated to be 52% for ensembles of 18 nm particles and 92% for 70 nm particles. It was found that applied hydrostatic pressure enhances T C of La 0.8 Ca 0.2 MnO 3 nanoparticles at a rate dT C / dP Ϸ 1.8-1.9 K / kbar, independently on the average particle size. Pronounced irreversibility of magnetization below T irr Ϸ 208 K and strong frequency dependent ac susceptibility below T C for smaller 18 nm particles have been observed. 18 nm particles have also shown aging and memory effects in zero-field-cooled ͑ZFC͒ and field-cooled magnetization. These features indicate the appearance of spin-glasslike state, partially reminiscent the behavior of La 1−x Ca x MnO 3 crystals, doped below the percolation thresholdx Ͻ x C = 0.225. In contrast, ensembles of larger 70 nm particles have shown insignificant irreversibility of magnetization only and no frequency dependence of ac susceptibility, similarly to the behavior of La 1−x Ca x MnO 3 crystals with x Ͼ x C . The temperature of the ZFC magnetization maximum for 18 nm particles decreases with increasing magnetic field and forms a critical line with an exponent 1.89Ϯ 0.56. The results suggest that superspin-glass features in ensembles of interacting 18 nm particles appear along with superferromagnetic-like features.

Asymmetric electroresistance of cluster glass state in manganites

“…35 MnO 3 thin films grown on SrTiO 3 by gating with ionic liquid in electric double layer transistors (EDLT). In such manganite films with strong phase separation, a cluster glass magnetic state emerges at low temperatures with a spin freezing temperature of about 99 K, which is accompanied by the reentrant insulating state with high resistance below 30 K. In the EDLT, we observe bipolar and asymmetric modulation of the channel resistance, as well as an enhanced electroresistance up to 200% at positive gate bias.…”

“…Prototypical PS manganites like La 5/8Ày Pr y Ca 3/8 MnO 3 (LPCMO) and Pr 0.65 (Ca y Sr 1Ày ) 0. 35 MnO 3 (PCSMO) have been extensively investigated. [5][6][7][8][9][10][11] In general, the dynamic fluid-like PS states and their glassy nature sensitively depend on the external parameters like temperature, magnetic field, and electric field.…”

High-pressure and high-temperature synthesis and physical properties of Ca2CrO4 solid

“…The features mentioned above indicate that Ca 2 CrO 4 exhibits spin glass magnetic behavior. 22,23 Temperature dependence of electrical resistivity of the sample exhibits an insulating behavior as shown in Fig. 6, the data below 70 K was absent for out of measurement limit.…”

Local structure and magnetic inhomogeneity of nano-sized La0.7Sr0.3MnO3 manganites

“…9) and La 0.8 Ca 0.2 MnO 3 (Ref. 25). We also suggested that the difference between the Mn neighborhood inside the crystalline core and disordered local structure of the outer shell matrix causes the broadening of the XANES spectrum of the NP2 powder.…”