Evidence for ferromagnetic clusters at room temperature in Dy and Mn site co-substituted compounds: Dy0.55Sr0.45Mn1-xFexO3

Short-range magnetic behavior in manganites La0.93K0.07Mn1- x Cu x O3 (0.0 ⩽ x ⩽ 0.09) above the Curie temperature

“…Simultaneously, Mn 4+ reduction leads, in turn, to reduction of the doubleexchange FM interactions responsible for the formation of magnetic clusters above T C . This behavior has been reported by other authors in similar systems [7]. The maximum of d (H/M) / dT was used to obtain Griffith's temperature [9] T G , as shown in the inset of figures 5 ) is clearly bigger than the one obtained for T ⩾ T * CW .…”

“…The experimental and theoretical values for µ eff are presented in table 3. It can be seen that µ eff experimental values are higher than the theoretical ones, as reported for other manganites[4,6,7,9,31]. This result is a signal of formation of clusters of short range magnetic order in the PM phase, which is widely faced in the polycrystalline manganites.…”

“…Some of the most interesting effects observed are the inhomogeneities in the magnetic phases and the coexistence of phases. Therefore, studies of the magnetic properties of La 1−x A x Mn 1−y B y O 3 manganites by doping at the A sites with alkaline ions [5] and B sites with transition metals [6][7][8], have contributed to understanding the already mentioned correlations for T > T C . Some of these doped manganites show short-range local FM structures above T C [9,10], analogous to the randomly diluted Ising ferromagnets described by [11].…”

Anomalous behavior above the Curie temperature in (Nd1−xGdx)0.55Sr0.45MnO3 (x = 0, 0.1, 0.3 and 0.5)

“…Among the various forms of phase separation, the concept of preformation of FM ordered clusters at some well defined temperature T * much above the FM long-range ordering temperature ( T C ) ( i.e ., still in the PM phase) is a widely accepted phenomenon. 6 This regime between T * and T C , was predicted by Griffiths 7 in diluted Ising ferromagnets and has since generated vested interests. 8 In its simplest form, the original problem considered the percolative nature of an Ising system to have the nearest neighbor (exchange) bonds characterized by a strength J occurring with a probability p ; otherwise, the bond strength is zero.…”

Influence of Nonmagnetic Dilution on the Magnetic Properties of La1−xDyxMn1−yZnyO3 Perovskites at High Temperature

“…These clusters have been, in all cases, related to the mentioned random magnetic disorder. [ 10–16 ] Also, it has been observed that in most of the ceramics doped, both at the site as in the Mn site, the inverse magnetic susceptibility in a certain regime above long‐range order, does not follow the Curie Weiss (CW) law, where C and are Curie constant and paramagnetic (PM) CW temperature, respectively. This law is the asymptotic behavior of magnetization at .…”