Enhancement of local magnetic ordering temperature due to non-magnetic disorder in anti-Heusler alloy Al2MnCu
Abstract
Structural disorder is generally regarded as detrimental to magnetism. Since magnetic properties are governed by both the arrangement of magnetic atoms and the crystal environment, including non-magnetic atoms that mediate exchange interactions, the distinct role of magnetic and non-magnetic disorder remains less understood. The recently reported anti-Heusler alloy, Al2MnCu, forming with ∼50\% intra-symmetry site disorder (B2) involving the magnetic Mn atom and ∼5\% inter-symmetry site disorder associated with non-magnetic Al and Cu atoms, offers a good platform to disentangle the individual roles of magnetic and non-magnetic atomic disorder. Our magnetic critical analysis, in the vicinity of the Curie temperature (TC), does not lead to any conventional single universality class expected for a standard ferromagnet; instead, the non-monotonic temperature dependence of effective critical exponents points towards more complex magnetic interactions, akin to inhomogeneous ferromagnets. Dc magnetometry complemented by higher-harmonic ac magnetic susceptibility data, further confirms the persistence of locally ordered magnetic clusters above TC. Theoretical analysis establishes that the enhancement of the local magnetic ordering temperature arises directly from the strengthening of exchange interactions due to the small degree of non-magnetic disorder, whereas TC is hardly influenced by the much larger level of magnetic-atom disorder. The combined experimental and theoretical investigations on the anti-Heusler alloy Al2MnCu reveal and explain the unusual observation of nonmagnetic disorder-induced elevation of TC, providing a paradigm for the counterintuitive role of disorder in magnetic materials.
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BibTeX
@misc{bhowmik2026enhancement,
title = {{Enhancement of local magnetic ordering temperature due to non-magnetic disorder in anti-Heusler alloy Al$_2$MnCu}},
author = {Soumya Bhowmik and Suvayan Saha and Saikat Debnath and Arka Patra and Biswarup Satpati and Maxim Avdeev and Shishir Kumar Pandey and Chandan Mazumdar},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.15622},
eprint = {2610.15622},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.15622},
}
RIS
TY - UNPB
TI - Enhancement of local magnetic ordering temperature due to non-magnetic disorder in anti-Heusler alloy Al_2MnCu
AU - Soumya Bhowmik
AU - Suvayan Saha
AU - Saikat Debnath
AU - Arka Patra
AU - Biswarup Satpati
AU - Maxim Avdeev
AU - Shishir Kumar Pandey
AU - Chandan Mazumdar
PY - 2026
DA - 2026/10/11
PB - arXiv
DO - 10.48550/arxiv.2610.15622
UR - https://arxiv.org/abs/2610.15622
AB - Structural disorder is generally regarded as detrimental to magnetism. Since magnetic properties are governed by both the arrangement of magnetic atoms and the crystal environment, including non-magnetic atoms that mediate exchange interactions, the distinct role of magnetic and non-magnetic disorder remains less understood. The recently reported anti-Heusler alloy, Al_2MnCu, forming with ∼50\% intra-symmetry site disorder (B2) involving the magnetic Mn atom and ∼5\% inter-symmetry site disorder associated with non-magnetic Al and Cu atoms, offers a good platform to disentangle the individual roles of magnetic and non-magnetic atomic disorder. Our magnetic critical analysis, in the vicinity of the Curie temperature (T_C), does not lead to any conventional single universality class expected for a standard ferromagnet; instead, the non-monotonic temperature dependence of effective critical exponents points towards more complex magnetic interactions, akin to inhomogeneous ferromagnets. Dc magnetometry complemented by higher-harmonic ac magnetic susceptibility data, further confirms the persistence of locally ordered magnetic clusters above T_C. Theoretical analysis establishes that the enhancement of the local magnetic ordering temperature arises directly from the strengthening of exchange interactions due to the small degree of non-magnetic disorder, whereas T_C is hardly influenced by the much larger level of magnetic-atom disorder. The combined experimental and theoretical investigations on the anti-Heusler alloy Al_2MnCu reveal and explain the unusual observation of nonmagnetic disorder-induced elevation of T_C, providing a paradigm for the counterintuitive role of disorder in magnetic materials.
ER -