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Underpinnings behind the magnetic order-to-disorder transition and property anomaly of disproportionated insulating samarium nickelate

Journal Article · · Acta Materialia
Perovskite nickelates (RNiO3), as benchmark materials for exploring underlying physics of phase transitions in strong correlated systems, are well-known for their rich structural characteristics and physicochemical properties. Understanding phase transition from the spin-ordered antiferromagnetic (AFM) state to the spin-disordered paramagnetic (PM) state of RNiO3 requires accurate models at finite temperatures. Here, we investigate the underpinning physics behind the property anomaly and AFM-to-PM transition in samarium nickelate (SmNiO3) using a thermodynamic zentropy approach, which depicts the temperature-dependent total entropy for a system of interest via a nested formula through integration of quantum mechanics and statistical mechanics. The SmNiO3 displays the ground-state of AFM insulator as well as the PM metal and PM insulator at elevated temperatures. It turns out that the magnetic configurational entropy induced by competition among different spatially fluctuating polymorphous spin configurations, contributes to the specific-heat anomaly and the phase transition of SmNiO3 from AFM to PM state. Here, the predicted Néel temperature of 241±25 K for SmNiO3 is in satisfactory agreement with the experimental value. Unlike empirical interpretations in literature, the present work indicates that the magnetic order-to-disorder transition in SmNiO3 is associated with the magnetic configurational entropy due to thermal mixture of multiple spin configurations at elevated temperatures, which can be quantitively captured by the first-principles based thermodynamic zentropy approach.
Research Organization:
Chongqing University (China); Northwestern Polytechnical University, Shaanxi (China); The Pennsylvania State University, University Park, PA (United States)
Sponsoring Organization:
China Association for Science and Technology; Fundamental Research Funds for the Central Universities; National Natural Science Foundation of China; Natural Science Foundation of Chongqing; Research Fund of the State Key Laboratory of Solidification Processing (NPU) China; USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES)
Grant/Contract Number:
SC0023185
Other Award/Contract Number:
3102020QD0412
CSTB2022NSCQ-MSX0369
52171013
52130110
2023-QZ-03
2020QNR001
OSTI ID:
3022571
Alternate ID(s):
OSTI ID: 2369780
OSTI ID: 2576329
Journal Information:
Acta Materialia, Journal Name: Acta Materialia Vol. 268; ISSN 1359-6454
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English