TY - JOUR
T1 - Understanding magnetic phase coexistence in Ru2Mn1-xFexSn Heusler alloys
T2 - A neutron scattering, thermodynamic, and phenomenological analysis
AU - McCalla, Eric
AU - Levin, Emily E.
AU - Douglas, Jason E.
AU - Barker, John G.
AU - Frontzek, Matthias
AU - Tian, Wei
AU - Fernandes, Rafael M.
AU - Seshadri, Ram
AU - Leighton, Chris
N1 - Publisher Copyright:
© 2021 American Physical Society.
PY - 2021/6
Y1 - 2021/6
N2 - The random substitutional solid solution between the antiferromagnetic (AFM) full-Heusler alloy Ru2MnSn and the ferromagnetic (FM) full-Heusler alloy Ru2FeSn provides a rare opportunity to study FM-AFM phase competition in a near-lattice-matched, cubic system, with full solubility. At intermediate x in Ru2Mn1-xFexSn this system displays suppressed magnetic ordering temperatures, spatially coexisting FM and AFM order, and strong coercivity enhancement, despite rigorous chemical homogeneity. Here, we construct the most detailed temperature- and x-dependent understanding of the magnetic phase competition and coexistence in this system to date, combining wide-temperature-range neutron diffraction and small-angle neutron scattering with magnetometry and specific heat measurements on thoroughly characterized polycrystals. A complete magnetic phase diagram is generated, showing FM-AFM coexistence between x≈0.30 and x≈0.70. Important insight is gained from the extracted length scales for magnetic phase coexistence (25-100 nm), the relative magnetic volume fractions and ordering temperatures, and remarkable x-dependent trends in magnetic and electronic contributions to specific heat. An unusual feature in the magnetic phase diagram (an intermediate FM phase) is also shown to arise from an extrinsic effect related to a minor Ru-rich secondary phase. The established magnetic phase diagram is then discussed with the aid of phenomenological modeling, clarifying the nature of the mesoscale phase coexistence with respect to the understanding of disordered Heisenberg models.
AB - The random substitutional solid solution between the antiferromagnetic (AFM) full-Heusler alloy Ru2MnSn and the ferromagnetic (FM) full-Heusler alloy Ru2FeSn provides a rare opportunity to study FM-AFM phase competition in a near-lattice-matched, cubic system, with full solubility. At intermediate x in Ru2Mn1-xFexSn this system displays suppressed magnetic ordering temperatures, spatially coexisting FM and AFM order, and strong coercivity enhancement, despite rigorous chemical homogeneity. Here, we construct the most detailed temperature- and x-dependent understanding of the magnetic phase competition and coexistence in this system to date, combining wide-temperature-range neutron diffraction and small-angle neutron scattering with magnetometry and specific heat measurements on thoroughly characterized polycrystals. A complete magnetic phase diagram is generated, showing FM-AFM coexistence between x≈0.30 and x≈0.70. Important insight is gained from the extracted length scales for magnetic phase coexistence (25-100 nm), the relative magnetic volume fractions and ordering temperatures, and remarkable x-dependent trends in magnetic and electronic contributions to specific heat. An unusual feature in the magnetic phase diagram (an intermediate FM phase) is also shown to arise from an extrinsic effect related to a minor Ru-rich secondary phase. The established magnetic phase diagram is then discussed with the aid of phenomenological modeling, clarifying the nature of the mesoscale phase coexistence with respect to the understanding of disordered Heisenberg models.
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U2 - 10.1103/PhysRevMaterials.5.064417
DO - 10.1103/PhysRevMaterials.5.064417
M3 - Article
AN - SCOPUS:85109033702
SN - 2475-9953
VL - 5
JO - Physical Review Materials
JF - Physical Review Materials
IS - 6
M1 - 064417
ER -