Giant volume magnetostriction in La0.85Ce0.15Fe12B6

We report the discovery of giant magnetostriction and huge negative thermal expansion (NTE) in the itinerant-electron metamagnetic compound La0.85Ce0.15Fe12B6. This system presents multiple magnetic transformations, antiferromagnetic–ferromagnetic (AFM–FM) and ferromagnetic–paramagnetic (FM–PM), driven by changes in both external field and temperature. The magnetic-field–dependent magnetostriction exhibits irreversible abrupt jumps at T ≤ 5 K, while it evolves smoothly with applied field above 5 K. A giant positive volume magnetostriction of ΔV/V (20 K, 6 T) = 0.80% is observed across the field-induced first-order AFM–FM metamagnetic transition. It is further revealed that the FM–PM transition is accompanied by a remarkably large NTE with a coefficient of linear thermal expansion αL = −34 × 10−6 K−1 over a temperature window of ΔT ∼ 63 K.