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Please use this identifier to cite or link to this item: http://repository.iitr.ac.in/handle/123456789/24558
Title: Evolution of the magnetic and charge orders in La0.15Pr0.45Ca0.40MnO3: Assessing the role of particle size and magnetic field
Authors: Raghav D.S.
Kumari S.
Singh H.K.
Siwach P.K.
Varma, Ghanshyam Das
Published in: Journal of Magnetism and Magnetic Materials
Abstract: The evolution of the ferromagnetic (FM)/antiferromagnetic (AFM) orders and charge order (CO) as a function of the particle size and applied magnetic field (H) has been studied in detail in the canonical phase-separated system La1−x−yPryCaxMnO3 with larger Pr content (La0.15Pr0.45Ca0.40MnO3). At lower particle size (~ 45 nm) a low TC FM phase dominates with no direct evidence of the AFM and CO phases in the magnetization (M) data. As the particle size increases, the AFM and CO grow with a concomitant decrease in the FM fraction, as shown by a decrease in the magnetization and explicit transitions. All three electronic orders become distinctly visible at particle size ~ 139 nm, with TCO ~ 213 K, TN ~ 173 K, and TC ~ 58 K. At larger sizes, e.g., ~ 370 nm, FM appears as the robust phase while the AFM and CO are quenched. However, the presence of the AFM/CO clusters in this sample is signed by the hysteresis in the FCC and FCW magnetization in the FM regime. The paramagnetic (PM) region susceptibility as a function of temperature exhibits scaling of the type χ=[Formula presented], where TCON is the temperature at which the FM response becomes visible. The exponent remains γ ≈ 1.17 for samples with less dominant CO. At the ~ 139 nm, the CO is the most robust, and the exponent takes a value γ ≈ 1.31. The effect of the magnetic field in the case of the ~ 139 nm samples shows that the AFM melts at HAFM ~ 40 kOe, while the CO melts at HCO ~ 50 kOe. The scaling of the paramagnetic regime susceptibility (H/M) at different H shows that γ remains confined to the range 1.30–1.34 up to 20 kOe, and then decreases slightly to ≈1.24 at 30 kOe. At the AFM melting magnetic field ~ 40 kOe, it drops to ≈1.13, and at further higher fields, the above scaling breaks down. Thus TCON remains a good substitute for the canonical TC in the scaling law χ=[Formula presented] in strongly phase-separated manganite. Our results show that a phase-separated system with FM dominance deviates from the Curie-Weiss law valid for canonical ferromagnets. However, the presence of explicit CO makes the H/M – T scaling akin to a 3D Heisenberg ferromagnet. © 2021 Elsevier B.V.
Citation: Journal of Magnetism and Magnetic Materials, 536
URI: https://doi.org/10.1016/j.jmmm.2021.168126
http://repository.iitr.ac.in/handle/123456789/24558
Issue Date: 2021
Publisher: Elsevier B.V.
Keywords: Antiferromagnetic charge ordering
Charge-ordering
Insulator-metal transition
Manganite
Phase separation
Rietveld-refinement
ISSN: 3048853
Author Scopus IDs: 57201685275
57200296956
55256917900
6507772782
14040828900
Author Affiliations: Raghav, D.S., Department of Physics, Indian Institute of Technology Roorkee, Roorkee, 247667, India
Kumari, S., CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi, 110012, India
Singh, H.K., CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi, 110012, India
Siwach, P.K., CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi, 110012, India
Varma, G.D., Department of Physics, Indian Institute of Technology Roorkee, Roorkee, 247667, India
Funding Details: D. S. Raghav acknowledges the University Grant Commission (UGC), New Delhi, for the award of the research fellowship. Suman Kumari acknowledges DST (Govt. of India) for the award of INSPIRE-JRF/SRF. Department of Science and Technology, Ministry of Science and Technology, India, डीएसटी; University Grants Commission, UGC
Corresponding Author: Varma, G.D.; Department of Physics, India; email: gdvarfph@gmail.com
Appears in Collections:Journal Publications [PH]

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