Antiferromagnetic rare region effect in Pr0.5Ca0.5MnO3

Abstract

We present evidence of coexistence of electron paramagnetic resonance signal and anti-ferromagnetic resonance signals above the antiferromagnetic (AFM) transition (TN ) in P r0.5Ca0.5M nO3. We identify the latter with AFM rare regions within the 'Griffiths-like' phase scenario with the associated temperature scale T * extending above room temperature.

Disorder perturbed flat bands: Level density and inverse participation ratio

“…This is because a comparison of the fluctuations of two different systems require a prior rescaling leading to same background behavior on which fluctuations are imposed. As discussed later in section IV as well as in [1], the rescaling depends on the local mean level spacing which is in general different for non-interacting and interacting cases.…”

“…The effect of disorder on the level density for case (c) is displayed in figure 2 (also see figures 2(a) -5(a) of [1]). Clearly for w < 1, R 1 /N is independent of disorder w as well as size N in the flat band but its behavior in dispersive band depends on the size.…”

“…Due to technical complications, the details of this case will be discussed elsewhere. For a clear visualization, the Gaussian fit for various disorder is not displayed here but is shown in [1] by the solid line fits in parts(a) of figures 2,3,4,5. The latter also confirms the size-independence of R 1 (e)/N for both all energy-ranges.…”

“…The information given in section IV is used in section V to derive the complexity parameter formulation of the density and the inverse participation ratio. As discussed in [1] (part II of this work), a knowledge of these measures is necessary to seek the criticality in disordered flat bands. We conclude in section VI with a brief summary of our main results.…”

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

“…On the other hand, the absence of GP for x ¼ 0, yet GP is observed near half-doped. 30 Indeed, the disorder arising from local lattice distortion is less likely to give rise to an inhomogeneous state and GP.…”