Origin of the large positive magnetoresistance in Ge1-xMnx granular thin films

Abstract

GeMn granular thin films are a unique and promising material for spintronics applications due to large positive magnetoresistance (MR). Previous studies on GeMn have suggested that the large MR is related to nanospinodal decomposition of GeMn into Mn-rich ferromagnetic nanoparticles and Mn-poor paramagnetic matrix. However, its microscopic origin of the MR has not been clarified yet. Here, using X-ray magnetic circular dichroism (XMCD), which is extremely sensitive to the local magnetic state of each atom, we investigate the magnetic properties of the nanoparticles and the matrix in GeMn separately. We find that the MR ratio is proportional to the product of the magnetizations originating from the nanoparticles and the matrix. This result indicates that spin-polarized holes in the nanoparticles penetrate into the matrix and that these holes undergo spin-disorder magnetic scattering by the paramagnetic Mn atoms in the matrix, which induces the large MR.

References in corpus (5)

• Spin-glass-like behavior of Ge:Mn
• Nature of magnetic coupling between Mn ions in as-grown Ga${}_{1-x}$Mn${}_x$As studied by x-ray magnetic circular dichroism
• Room temperature local ferromagnetism and nanoscale domain growth in the ferromagnetic semiconductor GeFe
• Interplay between the electrical transport properties of GeMn thin films and Ge substrates
• Core-shell nanostructure in a Ge_0.9Mn_0.1 film from structural and magnetic measurements

Cited by in corpus (3)

• Electronic structure and magnetic properties of magnetically dead layers in epitaxial CoFe2O4/Al2O3/Si(111) films studied by X-ray magnetic circular dichroism
• Isotropic orbital magnetic moments in magnetically anisotropic SrRuO3 films
• Systematic study of the electronic structure and the magnetic properties of a few-nm-thick epitaxial (Ni1-xCox)Fe2O4 (x = 0 - 1) layers grown on Al2O3(111)/Si(111) using soft X-ray magnetic circular dichroism: effects of cation distribution