Evolution of magnetic phases in SmCrO3: A neutron diffraction and magnetometric study

The classical belief about the mechanism of spin reorientation phase transition (SRPT) and ground-state magnetic structure in SmCrO3 has become intriguing because of inconsistent bulk magnetization observations. The presence of highly neutron-absorbing Sm atom has so far evaded the determination of...

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Bibliographic Details
Published in:Physical review. B 2017-11, Vol.96 (17)
Main Authors: Tripathi, Malvika, Choudhary, R J, Phase, D M, Chatterji, T, Fischer, H E
Format: Article
Language:English
Subjects:
Absorption
Anisotropy
Antiferromagnetism
Chromium
Configurations
Crystallography
Free energy
Magnetic structure
Neutron diffraction
Neutrons
Phase transitions
Phases
Thermal evolution
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Summary:The classical belief about the mechanism of spin reorientation phase transition (SRPT) and ground-state magnetic structure in SmCrO3 has become intriguing because of inconsistent bulk magnetization observations. The presence of highly neutron-absorbing Sm atom has so far evaded the determination of microscopic magnetic structure. In the present report, we have utilized very high-energy “hot neutrons” to overcome the Sm absorption and to determine the thermal evolution of magnetic configurations. Unambiguously, three distinct phases are observed: the uncompensated canted antiferromagnetic structure Γ4(Gx,Ay,Fz;FzR) occurring below the Néel temperature (TN=191 K), the collinear antiferromagnetic structure Γ1(Ax,Gy,Cz;CzR) occurring below 10 K, and a nonequilibrium configuration with cooccurring Γ1 and Γ4 phases in the neighborhood of the SRPT (10 K ≤T≤ 40 K). In differing to the earlier predictions, we divulge the SRPT to be a discontinuous transition where chromium spins switch from the a−b crystallographic plane to the b−c crystallographic plane in a discrete manner with no allowed intermediate configuration. The canting angle of chromium ions in the a−b plane is unusually not a thermal constant, rather it is empirically discerned to follow exponential behavior. The competition between magnetocrystalline anisotropy and free energy derived by isotropic and antisymmetric exchange interactions between different pairs of magnetic ions is observed to govern the mechanism of SRPT.
ISSN:2469-9950
2469-9969
DOI:10.1103/PhysRevB.96.174421