arXiv subjects

R. Bindu

Publications and source records attributed to R. Bindu.

21 records · Page 2Linked to original sources

arXiv2007

Electronic and structural transition in $La_{0.2} Sr_{0.8} Mn O_3$

We investigate the interplay of the electronic and structural transition in La$_{0.2}$Sr$_{0.8}$MnO$_{3}$. The transport and specific heat measurements exhibit unusual evolutions and signature of a first order phase transition around 265 K. Mn K-edge extended $x$-ray absorption fine structure results reveal distortion in the MnO$_6$ octahedra even in the cubic phase and a remarkable evolution of the distortion across the phase transition. These results manifest the importance of fluctuations in Mn 3$d$ orbital occupancy and disorder in their electronic properties, which may help in understanding the orbital and spin ordering proposed in these systems.

cond-mat.str-el↗

arXiv2007

Doping and bond length contributions to Mn K-edge shift in La$_{1-x}$Sr$_x$MnO$_{3}$ and their correlation with electrical transport properties

The experimental Mn K-edge x-ray absorption spectra of La$_{1-x}$Sr$_x$MnO$_{3}$, $x$ = 0 - 0.7 are compared with the band structure calculations using spin polarized density functional theory. It is explicitly shown that there is a correspondence between the inflection point on the absorption edge and the centre of gravity of the unoccupied Mn 4$p$-band. This correspondence has been used to separate the doping and size contributions to edge shift due to variation in number of electrons in valence band and Mn-O bond lengths, respectively when Sr is doped into LaMnO$_3$. Such separation is helpful to find the localization behaviour of charge carriers and to understand the observed transport properties of these compounds.

cond-mat.str-el↗

arXiv2006

Local distortion of MnO$_6$ octahedron in La$_{1-x}$Sr$_x$MnO$_{3+δ}$ (x = 0.1 to 0.9): an EXAFS study

Room temperature Mn K-edge extended x-ray absorption fine structure (EXAFS) studies were carried out on La$_{1-x}$Sr$_x$MnO$_{3+δ}$ (x = 0.1 to 0.9) compounds. It is found from the detailed EXAFS analysis that the local structure around Mn sites is different from the global structure inferred from x-ray diffraction, especially for x <= 0.4, indicating presence of local distortions in MnO$_6$ octahedra. For the rhombohedral compounds, x = 0.1 to 0.3 the distortion is maximum for x = 0.1 and two bond lengths are seen- short one in basal plane and long one in apical plane. For compounds with x = 0.4 to 0.8 two short bonds in basal plane and four long bonds- two in the basal plane and remaining two in the apical plane are seen. For the compounds up to x = 0.3 compositions long bond length decreases and short bond length increases with increase in x whereas for the compounds 0.4 <= x <= 0.8 both types of bond lengths decrease. Such behaviour of bond lengths is an indication of the changed nature of distortion from Jahn-Teller type to breathing type at x = 0.4 composition.

cond-mat.mtrl-sci↗