Ferromagnetism in 5f-band metamagnet UCoAl induced by Os doping

UCoAl is a 5f-band metamagnet with a uniquely low paramagnetic-to-ferromagnetic transition field, 0.7 T, extremely sensitive to any perturbation such as elemental substitution. Here, we study variations of magnetic properties in the UCoAl-UOsAl system on single- and polycrystalline samples with diff...

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Bibliographic Details
Published in:Journal of alloys and compounds 2016-10, Vol.681, p.275-282
Main Authors: Andreev, A.V., Shirasaki, K., Šebek, J., Vejpravová, J., Gorbunov, D.I., Havela, L., Daniš, S., Yamamura, T.
Format: Article
Language:English
Subjects:
Alloys
Curie temperature
Doping
Ferromagnetism
Itinerant metamagnetism
Laves phase
Magnetic fields
Magnetic properties
Phase shift
UCoAl
Uranium intermetallics
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Summary:UCoAl is a 5f-band metamagnet with a uniquely low paramagnetic-to-ferromagnetic transition field, 0.7 T, extremely sensitive to any perturbation such as elemental substitution. Here, we study variations of magnetic properties in the UCoAl-UOsAl system on single- and polycrystalline samples with different concentration of Os. We found that osmium can substitute Co in UCoAl up to 20%, while preserving the ZrNiAl structure type. Pure UOsAl was identified as a hexagonal Laves phase, MgZn2 type. It is a weak Pauli paramagnet. Even a 2%-substitution of Os for Co in the 5f band metamagnet stabilizes ferromagnetism with the Curie temperature TC = 26 K and uranium magnetic moment μU = 0.4 μB and shifts the critical metamagnetic field to zero. Higher Os concentrations enhance both TC and μU. All magnetic response is concentrated into the c-axis; the susceptibility for magnetic field perpendicular to c is low and practically temperature-independent. Our study reflects the decisive role of the 5f-5d hybridization in the magnetism of the UCoAl-UOsAl system. This work completes the study of the alloying of UCoAl with late transition metals and indicates that the non-magnetic phase exhibiting band metamagnetism is very limited in the concentration range. •This work completes the study of the alloying of UCoAl with late transition metals.•Even 2% Os doping in the 5f band metamagnet UCoAl stabilizes ferromagnetism.•At solubility limit 20% Os the compound is strong ferromagnet with Tc = 55 K.
ISSN:0925-8388
1873-4669
DOI:10.1016/j.jallcom.2016.04.226