Anomalous spin dynamics in the charge-ordered two-electron doped manganiteCa0.9Ce0.1MnO3: Possibility of a spin-liquid phase

Abstract

The 'two-electron' doped rare earth manganites Ca 1-x Ce x MnO 3 (x = 0.1, 0.2) are probed using resistivity, ac susceptibility and electron paramagnetic resonance (EPR) measurements across their respective charge ordering (CO) temperatures T CO = 180 K and 250 K. The EPR 'g' factor and intensity as well as the transport and magnetic behaviors of the two compositions are qualitatively similar and are as expected for CO systems.However, the EPR linewidth, reflective of the spin dynamics, for x = 0.1, shows a strongly anomalous temperature dependence, decreasing with decreasing temperature below T CO in contrast with the sample with x = 0.2 and other CO systems. Keeping in view the evidence for magnetic frustration in the system, we propose that the anomalous temperature dependence of the linewidth is the signature of the occurrence of a disorder driven spin liquid phase, present along with charge ordering.

Electron spin resonance study of spin correlations in charge-ordered La2−2xSr1+2xMn2O7(x=0.6)

“…A rectangular piece of sample with a of size of 2 ϫ 1 ϫ 0.5 mm 3 was cut to take magnetization and ESR measurements. This behavior is observed in other CO manganites as well 14,15 and is also consistent with the dc susceptibility data shown in Fig. The magnetization was measured using a superconducting quantum interference device magnetometer ͑Quantum Design, MPMS-7͒.…”

Realizing the ‘hindered charge ordered phase’ in nanoscale charge ordered manganites: magnetization, magneto-transport and EPR investigations

“…where H 0 is the centre field, H is the full width at half maximum, when divided by a factor of √ 3 it gives H pp (peak to peak linewidth), and A is a quantity proportional to the area under the curve. The two terms in the above equation describe the contributions from the clockwise and anti-clockwise circularly polarized components of microwave radiation and is necessary to include these because of the large width of the signals, typical for charge ordered perovskite manganites [22,23,40,41,18]. This particular equation has been shown to give excellent fits for the broad EPR lines observed from the charge ordered manganites [22,23,40,41,18].…”

Coexistence of ferromagnetic and antiferromagnetic phases in Nd0.5CaxSr0.5−xMnO3manganites

“…In manganites, the temperature dependent anomalous behavior of the linewidth is due to the contributions from dipolar interaction, demagnetizing fields, crystal field effects and antisymmetric exchange interactions. However, the observed magnitude of the linewidth arising from the dipolar interaction and demagnetizing fields is negligible [35]. The temperature dependent narrowed linewidth in the manganites is due to anisotropic interactions as well as DM interactions.…”

“…The values of E show that the Ca-rich and Sr-rich compositions of NCSMO have stronger intra-cluster interactions than those of the other compositions [13]. The ESR intensity deviates from the Curie-Weiss law, indicating that spin-lattice interaction is present in the vicinity of T C which results in the formation Jahn-Teller polarons [30,35]. This electron-phonon coupling or the Jahn-Teller coupling arises from real space ordering of Mn 3+ and Mn 4+ ions.…”