Effects of Dy sub lattice dilution on transport and magnetic properties in Dy1-xKxMnO3

Abstract

Interaction of multiple oxidation states of manganese ions with rare earth ions in manganites leads to the observation of various magnetic ground states. To understand the effect of average ionic size on electrical conductivity and magnetic ground state properties in Dy1-xKxMnO3 (x=0.0, 0.1, 0.2 & 0.3), we have investigated electron transport as a function of temperature and magnetic properties as a function of temperature, frequency and magnetic field of these compounds. Although mixed valent manganese ions can facilitate a double exchange interaction via oxygen ion leading to a ferromagnetic metallic ground state, no insulator-metal transition was detected. On the other hand, in the compounds with x=0.0 to 0.2, transport properties suggested an adiabatic small polaron hopping conduction mechanism. However, x=0.3 compound followed a variable range hopping conduction. Temperature variation of magnetization data exhibited three different types of transitions involving Mn and Dy ions. The bifurcation between zero field cooled and field cooled magnetization data was observed in all the compounds. Field-dependent magnetization of all the compounds showed hysteresis loops for temperatures less than 10 K. Although large irreversibility between zero field cooled and field cooled magnetization data was observed with a peak for x=0.3, the peak temperatures did not alter with frequency ruling out the possibility of spin glass behavior. The presence of hysteresis loops and lack of saturation magnetization implied the simultaneous presence of ferromagnetic and antiferromagnetic exchange interactions well within the antiferromagnetic ordering of Mn ions.

Effect of calcining temperature on the microstructure and magnetic properties of CuFeO2 multiferroic ceramic

“…The above behaviours should be ascribed to the canting of magnetic spins in range of magnetic transition temperature. Similar results can also be observed in the latest studies of spin frustrated antiferromagnets materials [31]. From Figure 6, it should be noted that the value of saturation magnetisation (Ms) of the experimental samples exhibits quite different, from 3.65 to 23.22 emu g −1 .…”

Effect of Mn doping on the microstructure and magnetic properties of CuFeO2 ceramics

“…The anti-parallel spin ordering in CFOs may be affected by vacancies, improving their magnetic properties; (3) the substitution of Fe by Mn in CFOs can change the bond lengths and angles, changing the inclination angle of FeO 6 octahedron, which modulates the system's magnetic spin and improves the magnetic properties; (4) the greater the Fe 3+ ion content, the greater the magnetization. Compared with the studies on Ti-doped CFO [32], in cases of the same valence ion substitution, the magnetic structure deformation caused by small-size ion doping, and the competitive effect among ions of different magnetic moments is more significantly conducive to improving the magnetic properties of CFO systems. In conclusion, changes in the microstructures, grain sizes, charge compensation, and magnetic moments of different ions are important factors affecting the magnetic properties of CFO systems.…”

“…The samples' magnetization is unsaturated under the measured field of 0.5, indicating the presence of multiple magnetic interactions [31]. The x = 0.00-0.03 samples' M-H curves exhibit linear field-dependent magnetization, indicating their antiferromagnetic behavior, while the x = 0.05-0.10 samples demonstrate typical and symmetric hysteresis loop characteristics, indicating the presence of weak CFO-based ferromagnetism due to the short-range Fe-O-Fe interactions induced by Mn doping [28,32].…”

“…The magnetic properties of CFO ceramics improved by element doping was previously reported by Refs. [11,32,33]. The structure and area of the M-H loop are closely related to the material's particle size, composition, pore size, and cation distribution [34,35].…”

Modification of low temperature magnetic interactions in Dy1−xEuxMnO3

“…3(a) shows temperature dependence of electrical resistivity, r(T) of Dy 1Àx Eu x MnO 3 from 150 K to 300 K. It is observed that the semiconducting behavior persists in the whole temperature range of measurement. In order to understand the charge transport mechanism for the observed semiconducting behavior, various models such as thermal activation process involving nearest neighbor hopping 23,24 (Arrhenius law), hopping of small polarons (SPH) in the adiabatic approximation [25][26][27] and variable range hopping 28 (VRH) conduction process were used to t the r(T) data. The equation for thermal activation process for nearest neighbor hopping conduction with activation energy (E a ) is given by Arrhenius equation: …”