Evidence of collective relaxation behavior in the reentrant phase of oxygen-rich LaMnO3

Nonequilibrium magnetic properties in oxygen-rich LaMnO3 nanoparticles

“…Then δ ≈ 0.21 was obtained via the equation: %Mn 4+ = 2 × 100δ [17]. These results are well consistent with the literature data for LaMnO 3+δ samples with the rhom bohedral structure [17,18,20]. According to the magnetic phase diagram [17,18], LaMnO 3.21 falls in the MCS region.…”

“…Slightly below T g the FC curves exhibit a less pronounced cusp and plateau, which is also an indication of the SSG in nanoparticle systems [25]. Similar behavior is reported in the oxygenrich LaMnO 3 crystals and nanoparti cles [17][18][19][20][21], indicating that the behaviour could be a general character in the oxygenrich samples. In order to find out the underlining natures of the low temperature state, it should be firstly to clarify whether the freezing behavior results from the collective frozen of the glassy state or merely the simple blocking state of the LaMnO 3+δ nanoparticles.…”

“…As seen from figure 5(b), the experimental data can be fitted by the function. But the fitting yields T 0 = 25.3 K. This does not agree with the memory effect at T 1 = 26 K. More importantly, the fitting parameter τ 0 = 5 × 10 −15 s is six order smaller than the typical value for cluster glass systems in LaMnO 3 [20]. Since the Vogel-Fulcher law is an approach to describe the SSG or CS, the failure of fitting here means that the glassy behaviors would have other origin.…”

“…A reentrant glassy behaviour from the hightemperature anti ferromagnetic or ferromagnetic states has been evidenced in oxygenrich LaMnO 3+δ crystal and nanoparticle samples with δ ranging from 0.05 to 0.22. It is usually ascribed to the CG originating from the interaction between ferromagnetic clusters via the matrix [17][18][19][20]. For some other nanoparticle samples, SSG behaviour is reported to rise from the coupling between ferromagnetic nanoparticles as well [12].…”