物理学报2026，Vol.75Issue(7)：328-336,9.DOI:10.7498/aps.75.20251581
费米能级调控半金属Co基Heusler合金的磁致伸缩效应
Magnetostriction in Fermi-level-tuned half-metallic Co-based Heusler alloys
摘要
Abstract
Magnetostriction and spin polarization are two fundamental yet typically uncorrelated properties of magnetic materials.While magnetostriction reflects the strength of magnetoelastic coupling,spin polarization is determined by the spin-resolved electronic states near the Fermi level.Establishing a link between these two properties remains a significant challenge.In this work,we demonstrate that Fermi-level engineering in Co2FeAlxSi1-x.Heusler alloys provides an effective route to simultaneously enhance spin polarization,magnetostriction and temperature stability.First-principles calculations reveal that Co2FeAlxSi1-x exhibits a strongly suppressed density of states in the minority-spin channel near the Fermi level across the entire composition range,characteristic of a minority-spin pseudogap.With increasing Al/Si ratio,the Fermi level shifts continuously from the lower edge of the pseudogap(x=1)to the upper edge(x=0),and resides close to the center of the pseudogap at x≈0.5.This electronic configuration leads to the highest calculated spin polarization and the maximum magnetostriction coefficient,both showing pronounced non-monotonic composition dependence.Polycrystalline samples across x=0-1 were synthesized to verify these predictions.Room-temperature magnetostriction measurements confirm that the saturation magnetostriction λs peaks at x ≈ 0.5,in excellent agreement with theoretical calculations.Temperature-dependent measurements(80-300 K)show that the magnetostriction of all compositions follows the Bloch T3/2 law,indicating that thermal excitation of spin waves is one of the primary mechanisms responsible for the temperature-induced reduction of magnetostriction.The extracted decay constant β is significantly reduced for intermediate compositions compared with the end-member alloys,and the low-temperature enhancement ratio R is also markedly smaller in this composition range,reflecting superior magnetostriction stability against thermal excitations.This enhanced stability can be attributed to the improved stability of spin polarization when the Fermi level resides near the center of the minority-spin pseudogap,which in turn weakens the impact of thermally excited spin waves on the magnetoelastic response.Further analysis indicates that the enhanced effectiveness of spin-orbit-coupling-induced modulation of magnetocrystalline anisotropy in this electronic configuration constitutes the key microscopic mechanism linking spin and lattice degrees of freedom,thereby enabling strong magnetoelastic coupling.These results establish an electronic-structure-based mechanism linking magnetostriction and spin polarization and provide a design principle for multifunctional Heusler materials with coupled magnetic and magnetoelastic performance.关键词
磁致伸缩/自旋极化率/Co基Heusler合金Key words
magnetostriction/spin polarization/Co-based Heusler alloys引用本文复制引用
姚亮,吴鹏举,杜杰,刘永昌,郗学奎,王文洪..费米能级调控半金属Co基Heusler合金的磁致伸缩效应[J].物理学报,2026,75(7):328-336,9.基金项目
国家重点研发计划(批准号:2024YFF0726700)和国家自然科学基金(批准号:12274321,12361141823)资助的课题. Project supported by the National Key Research and Development Program of China(Grant No.2024YFF0726700)and the National Natural Science Foundation of China(Grant Nos.12274321,12361141823). （批准号:2024YFF0726700）
