Electron Magnetic Resonance Studies of Nanosized Nd0.65Ca0.35 Mn1−xCrxO3 (x = 0, 0.06, 0.1) Manganite

• Published in: Applied magnetic resonance Vol. 46; no. 9; pp. 1059 - 1068
• Main Authors: Paul, Daly, Anuradha, K. N., S Bhagyashree, K., Bhat, S. V.
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01-09-2015; Springer Nature B.V
• Subjects: Atoms and Molecules in Strong Fields; Chromium; Doping; Ferromagnetic resonance; Ferromagnetism; Laser Matter Interaction; Magnetic fields; Nanoparticles; Organic Chemistry; Particle size; Physical Chemistry; Physics; Physics and Astronomy; Scanning electron microscopy; Sol-gel processes; Solid State Physics; Spectroscopy/Spectrometry; Temperature; Temperature dependence; Ferromagnetic Transition; Chromium Doping; Manganite; Resonance Field; Electron Magnetic Resonance
• ISSN: 0937-9347; 1613-7507
• DOI: 10.1007/s00723-015-0682-3

We report a systematic investigation of the temperature dependence of electron magnetic resonance (EMR) line width, intensity and resonance field for ~25 nm Nd
0.65
Ca
0.35
MnO
3
(NCMO1), Nd
0.65
Ca
0.35
Mn
0.94
Cr
0.06
O
3
(NCMO2) and Nd
0.65
Ca
0.35
Mn
0.9
Cr
0.1
O
3
(NCMO3) nanoparticles prepared by sol–gel method. The EMR line widths for the three nano-samples differ significantly from one another below a temperature
T
min
where the line width has a minimum.
T
min
was found to be 130, 100 and 120 K for NCMO1, NCMO2 and NCMO3, respectively. Well above
T
min
the line width values for the three samples are close to one another. The sharp upturn of EMR line width below
T
min
is attributed to the formation of short range, ferromagnetically ordered clusters. Temperature dependence of EMR intensity shows a residual CO transition in NCMO1 and NCMO2 and a complete disappearance of it in NCMO3. The intensity undergoes significant increase below 120, 80 and 100 K for NCMO1, NCMO2 and NCMO3, respectively, indicating the onset of ferromagnetic transitions. The occurrence of ferromagnetic transition is further confirmed by magnetization hysteresis measurements. The decrease in
T
C
in NCMO2 and NCMO3 compared to NCMO1 nanoparticles is understood to be due to the destruction of the double-exchange interaction by chromium doping. The resonance field decreases below the ferromagnetic onset temperatures for all the samples as expected. The combined effects of the reduction in size and of chromium doping in Mn site are discussed.