Magnetic Glassiness below Curie Temperature in La_0.8Ca_0.2MnO₃

Abstract

The magnetic and structural behaviors of a single crystal of La 0:8 Ca 0:2 MnO 3 were investigated in terms of magnetic and neutron diffraction measurements. The frequency-dependent ac magnetic susceptibility reveals that cluster-glassy phase evolves below the Curie temperature (T C ) in this system, suggesting the existence of short-range correlation below T C embedded in the ferromagnetic (FM) background. A correlation of the magnetic properties in La 0:8 Ca 0:2 MnO 3 with the buckling of MnO 6 octahedra is discussed based on its temperature-dependent neutron and magnetization data.

Magnetic phase transition and clustered state in Ca-doped lanthanum cobaltite and manganite with insulator ground states

“…The temperature dependences of |M 3 | and phase components of χ are presented in figures 5(b) and (a), respectively. The temperature position of the maximum at the largest temperature in |M 3 (T )| indicates T C ≈ 177 K which coincides with kinks in χ (T ), χ (T ) dependences (figure 5(a)) and is remarkably close to that (≈176 K) found in manganite with the same composition [25]. The behavior of χ (τ )(τ = (T − T C )/T C ) at τ > 0.04 corresponds to that of a 3D isotropic ferromagnet, χ (τ ) ∝ 1/τ −γ , with the critical index γ ≈ 4/3 (inset in figure 5(a)).…”

“…Changing the regime of temperature treatment of the LC02MO crystal from slow cooling to slow heating is not accompanied by any noticeable changes in temperature dependences of the M 2 response parameters, as the insets in figure 8 and figure 9 show. Such behavior of our manganite is more surprising than that of the LC02CO cobaltite because of the probable presence of the cooperative JT distortions in the LC02MO since they were found in the compound with the same composition and T C [25]. This result indicates again the weak coupling of the cluster moments with the lattice and suggest a symmetrization of the structure inside FMM clusters due to a decreasing of the amount of Mn 3+ ions with localized e g electrons at their origination.…”

“…They are insulators, to distinguish them from the previous LaSr pair of x = 0.18 cobaltite and x = 0.17 manganite. The LC02MO reveals orthorhombic Pbnm symmetry with coherent Jahn-Teller distortions below room temperature [25], whereas in LC02CO the structural transition from rhombohedral (R-3c) to orthorhombic (Pbnm) lattice symmetry without cooperative JT distortions occurs around 150 K [8]. Local JT distortions are very much small in the last and are not detected by the pair density function (PDF) approach [24].…”

Reentrant Superspin Glass Phase in aLa0.82Ca0.18MnO3Ferromagnetic Insulator

“…An enlightening report on the magnetic properties of a single crystal of La 0.8 Ca 0.2 MnO 3 , which is closer to the FMM composition, using ac techniques is found in Ref. [17], however without considering nonequilibrium (aging) and nonlinear field effects. Here, we investigate in detail the static and dynamical magnetic properties of a single crystal of La 0.82 Ca 0.18 MnO 3 (LCMO18) whose composition lies within the FMI regime (0.05 < x < 0.22).…”