Coexistence of Antiferromagnetic Cubic and Ferromagnetic Tetragonal Polymorphs in Epitaxial CuMnSb

Abstract

High-resolution transmission electron microscopy and superconducting quantum interference device magnetometry shows that epitaxial CuMnSb films exhibit a coexistence of two magnetic phases, coherently intertwined in nanometric scales. The dominant $\alpha$~phase is half-Heusler cubic antiferromagnet with the Néel temperature of 62~K, the equilibrium structure of bulk CuMnSb. The secondary phase is its ferromagnetic tetragonal $\beta$ polymorph with the Curie temperature of about 100~K. First principles calculations provide a consistent interpretation of experiment, since (i) total energy of $\beta$--CuMnSb is higher than that of $\alpha$--CuMnSb only by 0.12~eV per formula unit, which allows for epitaxial stabilization of this phase, (ii) the metallic character of $\beta$--CuMnSb favors the Ruderman-Kittel-Kasuya-Yoshida ferromagnetic coupling, and (iii) the calculated effective Curie-Weiss magnetic moment of Mn ions in both phases is about $5.5{\mu }_{\mathrm{B}}$, favorably close to the measured value. Calculated properties of all point native defects indicate that the most likely to occur are ${\mathrm{Mn}}_{\mathrm{Cu}}$ antisites. They affect magnetic properties of epilayers, but they cannot induce the ferromagnetic order in CuMnSb. Combined, the findings highlight a practical route towards fabrication of functional materials in which coexisting polymorphs provide complementing functionalities in one host.

14 pages, 8 figures, 5 tables

References in corpus (14)

• Role of the conduction electrons in mediating exchange interactions in Heusler alloys
• Heusler 4.0: Tunable Materials
• Imaging current-induced switching of antiferromagnetic domains in CuMnAs
• Crossover from antiferromagnetic to ferromagnetic ordering in semi-Heusler alloys Cu1-xNixMnSb with increasing Ni concentration
• Wurtzite vs rock-salt MnSe epitaxy: electronic and altermagnetic properties
• Defect-driven antiferromagnetic domain walls in CuMnAs films
• Physical properties of the tetragonal CuMnAs: a first-principles study
• Modeling magnetic evolution and exchange hardening in disordered magnets: The example of Mn${}_{1-x}$Fe${}_x$Ru${}_2$Sn Heusler alloys
• Magnetic properties of wurtzite (Ga,Mn)As
• Transition metal ions in ZnO: effects of intrashell Coulomb repulsion on electronic properties
• Magnetic Constitution of Topologically Trivial Thermoelectric PbTe:Cr
• Understanding Magnetic Phase Coexistence in Ru${}_2$Mn${}_{1-x}$Fe${}_x$Sn Heusler Alloys: A Neutron Scattering, Thermodynamic, and Phenomenological Analysis
• Bulk-like magnetic properties in MBE-grown unstrained, antiferromagnetic CuMnSb
• Probing the Manipulation of Antiferromagnetic Order in CuMnAs Films Using Neutron Diffraction

Cited by in corpus (1)

• Magnetic Phase Diagram of Mn3+xSn1-x Epitaxial Thin Films: Extending the Anomalous Hall Effect to Low Temperatures via Intrinsic Alloying