Structural, electrical, magnetic, and thermal studies of Cr-doped La 0.7 Ca0.3 Mn1-x CrxO3 (0≤x≤1) manganites

Neeraj Kumar, H. Kishan, Ashok Rao, V. P.S. Awana

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Abstract

We report detailed structural, electrical, magnetic, and specific heat studies on La0.7 Ca0.3 Mn1-x Crx O3 manganites. Rietveld analysis of fitted and observed x-ray diffraction patterns exhibited the single-phase nature of all the studied materials, which crystallize in Pbnm space group. Successive substitution of Cr at Mn-site in La0.7 Ca0.3 Mn1-x Crx O3 manganites increases the electrical resistivity and decreases the characteristic insulator-metal transition temperature (TIM) of the parent compound along with a humplike feature for higher Cr-content (x>0.06) samples. The hump structure basically signifies the onset of antiferromagnetic (AFM) interactions as inferred by both the magnetic and infrared (IR) spectroscopy studies. The systematic suppression of FM state results in a spin glass (SG)-like behavior. IR studies revealed that the vibration mode at 413 cm-1 being associated with internal bending of MnO6 octahedra, becomes softer, indicating an increase in distortion and hence the possible SG behavior. The critical exponents (α, Β, and γ) are calculated from the heat capacity (CP) data near the TIM / TFM. The same exhibited variations of their values with doping. In particular, the value of Β increases from 0.37 (x=0.0) to 0.43 (x=0.04), clearly indicating the coexistence of both long and short range magnetic orders, i.e., tendency toward SG state for Cr-doped samples. On the basis of present results, it is suggested that Cr dilutes double-exchange based FM and rather promotes the AFM based superexchange interactions via Cr3+ / Mn4+ ions. Substitution of Cr systematically destroys both the metallic state and long range FM order.

Original languageEnglish
Article number083905
JournalJournal of Applied Physics
Volume107
Issue number8
DOIs
Publication statusPublished - 15-04-2010

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frequency modulation
spin glass
heat
magnetic spectroscopy
transition temperature
specific heat
substitutes
vibration mode
tendencies
x ray diffraction
diffraction patterns
infrared spectroscopy
retarding
insulators
interactions
exponents
electrical resistivity
metals
ions

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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title = "Structural, electrical, magnetic, and thermal studies of Cr-doped La 0.7 Ca0.3 Mn1-x CrxO3 (0≤x≤1) manganites",
abstract = "We report detailed structural, electrical, magnetic, and specific heat studies on La0.7 Ca0.3 Mn1-x Crx O3 manganites. Rietveld analysis of fitted and observed x-ray diffraction patterns exhibited the single-phase nature of all the studied materials, which crystallize in Pbnm space group. Successive substitution of Cr at Mn-site in La0.7 Ca0.3 Mn1-x Crx O3 manganites increases the electrical resistivity and decreases the characteristic insulator-metal transition temperature (TIM) of the parent compound along with a humplike feature for higher Cr-content (x>0.06) samples. The hump structure basically signifies the onset of antiferromagnetic (AFM) interactions as inferred by both the magnetic and infrared (IR) spectroscopy studies. The systematic suppression of FM state results in a spin glass (SG)-like behavior. IR studies revealed that the vibration mode at 413 cm-1 being associated with internal bending of MnO6 octahedra, becomes softer, indicating an increase in distortion and hence the possible SG behavior. The critical exponents (α, Β, and γ) are calculated from the heat capacity (CP) data near the TIM / TFM. The same exhibited variations of their values with doping. In particular, the value of Β increases from 0.37 (x=0.0) to 0.43 (x=0.04), clearly indicating the coexistence of both long and short range magnetic orders, i.e., tendency toward SG state for Cr-doped samples. On the basis of present results, it is suggested that Cr dilutes double-exchange based FM and rather promotes the AFM based superexchange interactions via Cr3+ / Mn4+ ions. Substitution of Cr systematically destroys both the metallic state and long range FM order.",
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Structural, electrical, magnetic, and thermal studies of Cr-doped La 0.7 Ca0.3 Mn1-x CrxO3 (0≤x≤1) manganites. / Kumar, Neeraj; Kishan, H.; Rao, Ashok; Awana, V. P.S.

In: Journal of Applied Physics, Vol. 107, No. 8, 083905, 15.04.2010.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Structural, electrical, magnetic, and thermal studies of Cr-doped La 0.7 Ca0.3 Mn1-x CrxO3 (0≤x≤1) manganites

AU - Kumar, Neeraj

AU - Kishan, H.

AU - Rao, Ashok

AU - Awana, V. P.S.

PY - 2010/4/15

Y1 - 2010/4/15

N2 - We report detailed structural, electrical, magnetic, and specific heat studies on La0.7 Ca0.3 Mn1-x Crx O3 manganites. Rietveld analysis of fitted and observed x-ray diffraction patterns exhibited the single-phase nature of all the studied materials, which crystallize in Pbnm space group. Successive substitution of Cr at Mn-site in La0.7 Ca0.3 Mn1-x Crx O3 manganites increases the electrical resistivity and decreases the characteristic insulator-metal transition temperature (TIM) of the parent compound along with a humplike feature for higher Cr-content (x>0.06) samples. The hump structure basically signifies the onset of antiferromagnetic (AFM) interactions as inferred by both the magnetic and infrared (IR) spectroscopy studies. The systematic suppression of FM state results in a spin glass (SG)-like behavior. IR studies revealed that the vibration mode at 413 cm-1 being associated with internal bending of MnO6 octahedra, becomes softer, indicating an increase in distortion and hence the possible SG behavior. The critical exponents (α, Β, and γ) are calculated from the heat capacity (CP) data near the TIM / TFM. The same exhibited variations of their values with doping. In particular, the value of Β increases from 0.37 (x=0.0) to 0.43 (x=0.04), clearly indicating the coexistence of both long and short range magnetic orders, i.e., tendency toward SG state for Cr-doped samples. On the basis of present results, it is suggested that Cr dilutes double-exchange based FM and rather promotes the AFM based superexchange interactions via Cr3+ / Mn4+ ions. Substitution of Cr systematically destroys both the metallic state and long range FM order.

AB - We report detailed structural, electrical, magnetic, and specific heat studies on La0.7 Ca0.3 Mn1-x Crx O3 manganites. Rietveld analysis of fitted and observed x-ray diffraction patterns exhibited the single-phase nature of all the studied materials, which crystallize in Pbnm space group. Successive substitution of Cr at Mn-site in La0.7 Ca0.3 Mn1-x Crx O3 manganites increases the electrical resistivity and decreases the characteristic insulator-metal transition temperature (TIM) of the parent compound along with a humplike feature for higher Cr-content (x>0.06) samples. The hump structure basically signifies the onset of antiferromagnetic (AFM) interactions as inferred by both the magnetic and infrared (IR) spectroscopy studies. The systematic suppression of FM state results in a spin glass (SG)-like behavior. IR studies revealed that the vibration mode at 413 cm-1 being associated with internal bending of MnO6 octahedra, becomes softer, indicating an increase in distortion and hence the possible SG behavior. The critical exponents (α, Β, and γ) are calculated from the heat capacity (CP) data near the TIM / TFM. The same exhibited variations of their values with doping. In particular, the value of Β increases from 0.37 (x=0.0) to 0.43 (x=0.04), clearly indicating the coexistence of both long and short range magnetic orders, i.e., tendency toward SG state for Cr-doped samples. On the basis of present results, it is suggested that Cr dilutes double-exchange based FM and rather promotes the AFM based superexchange interactions via Cr3+ / Mn4+ ions. Substitution of Cr systematically destroys both the metallic state and long range FM order.

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