Regensburg 2019 – scientific programme

Parts | Days | Selection | Search | Updates | Downloads | Help

MA: Fachverband Magnetismus

MA 23: Soft and hard permanent bulk magnets

MA 23.6: Talk

Tuesday, April 2, 2019, 15:15–15:30, H53

Coercivity and anisotropy measurements on GdCo_5−xCu_x single crystals — •Stefan Giron, Léopold V.B. Diop, Iliya A. Radulov, Konstantin P. Skokov, and Oliver Gutfleisch — TU Darmstadt, FB Materialwissenschaft, Alarich-Weiss-Str. 16, 64287 Darmstadt, Germany

Rare-earth transition-metal permanent-magnets possess remarkably high anisotropy energies and therefore may express high coercivities necessary for permanent-magnet applications. Nonetheless, coercivity is limited to approximately one third of the anisotropy field (Brown’s paradox). Coercivity mechanisms driven by exchange interaction (e.g. exchange bias) recently observed in compensated bulk Heuslers [1] and Heusler segregations [2] provide the means necessary to overcome Brown’s paradox. Though not fully understood, the coexistence of FM and AFM clusters seems to be necessary in these systems. Materials with a compensation point (e.g. GdCo_5−xCu_x [3]) present themselves as model objects to study giant coercivity near the FM-AFM transition. We investigated a series of ferrimagnetic GdCo_5−xCu_x single crystals (x ∈ 0.5,1,1.5,2), which traverse a composition dependent compensation point. We show that the fields needed to demagnetize the samples approach their maximum (above 14T) near the compensation point, where the respective anisotropy fields reach minimum values.

[1] Nayak et al. Nature Materials, 2015, 14, 679

[2] Çakir, Scientific Reports, 2016, 6

[3] Grechishkin et al. Applied Physics Letters, 2006, 89, 122505