Crystal and magnetic structure of La${}_{1-x}$Ca${}_x$MnO${}_3$ compound $(0.11\leq x\leq 0.175

Abstract

We studied the crystal and magnetic structure of the La${}_{1-x}$Ca${}_x$MnO${}_3$ compound for $(0.11\le x\le 0.175)$ using stoichiometric samples. For $x<0.13$ the system's ground state is insulating canted antiferromagnetic. For $0.13\le x\le 0.175$ e below the Jahn Teller transition temperature ($T_{\mathrm{JT}}$) the crystal structure undergoes a monoclinic distortion. The crystal structure can be described with $P{2}_1/c$ space group which permits two Mn sites. The unit cell strain parameter $s=2(a-c)/(a+c)$ increases for $T<T_{\mathrm{JT}}$, taking the maximum value at the Curie point, and then decreases. Below $T_{{\mathrm{M}}^{/}{\mathrm{M}}^{//}}\approx 60$ K $s$ abruptly changes slope and finally approaches T=0 K with nearly zero slope. The change of $s$ at $T_{{\mathrm{M}}^{/}{\mathrm{M}}^{//}}$ is connected to a characteristic feature in the magnetic measurements. As $x$ increases towards the ferromagnetic metallic boundary, although $s$ is reduced appreciably, the monoclinic structure is preserved. The monoclinic structure is discussed with relation to the orbital ordering, which can produce the ferromagnetic insulating ground state. We also studied samples that were prepared in air atmosphere. This category of samples shows ferromagnetic insulating behavior without following the particular variation of the $s$ parameter. The crystal structure of these samples is related to the so-called O${}^{\ast }$ ($c>a>b/\sqrt{2}$) structure.

References in corpus (10)

• Unconventional Ferromagnetic Transition in La1-xCaxMnO3
• Transition between two ferromagnetic states driven by orbital ordering in La_{0.88}Sr_{0.12}MnO_3
• Approach to the metal-insulator transition in La(1-x)CaxMnO3 (0<x<.2): magnetic inhomogeneity and spin wave anomaly
• Two ferromagnetic phases in La1-xSrxMnO3(x ~1/8)
• Charge and orbital ordering in underdoped La1-xSrxMnO3
• Strain selection of charge and orbital ordering patterns in half-doped manganites
• Vertical Boundary at x ~ 0.11 in the Structural Phase Diagram of the La1-xSrxMnO3 System (0.08 <= x <= 0.125)
• Orbital domain state and finite size scaling in ferromagnetic insulating manganites
• Phase diagram and magnetic properties of La${}_{1-x}$Ca${}_x$MnO${}_3$ compound for $0\le x\le 0.23$
• Orbital dynamics: The origin of the anomalous optical spectra in ferromagnetic manganites

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• Relationship between macroscopic physical properties and local distortions of low doping La{1-x}Ca{x}MnO3: an EXAFS study
• Effect of oxygen isotope substitution and crystal micro-structure on magnetic ordering and phase separation in {$(\mathrm{L}{\mathrm{a}}_{1-\mathrm{y}}\mathrm{P}{\mathrm{r}}_{\mathrm{y}}{)}_{0.7}\mathrm{C}{\mathrm{a}}_{0.3}\mathrm{Mn}{\mathrm{O}}_3$}
• Ferromagnetic Domain Structure of La0.78Ca0.22MnO3 Single Crystals
• Interplay of magnetic order and Jahn-Teller distortion in a model with strongly correlated electron system
• Spin-charge and spin-orbital coupling effects on spin dynamics in ferromagnetic manganites