Regensburg 2010 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 24: Spinelectronics / Spin Injection in Heterostructures

MA 24.6: Vortrag

Donnerstag, 25. März 2010, 11:30–11:45, H22

Growth and characterization of ferromagnetic MnGa on GaN — •Christian Zube, Amilcar Bedoya-Pinto, Daniel Broxtermann, Till Benter, Jörg Malindretos, and Angela Rizzi — IV. Physikalisches Institut Universität Göttingen,D-37077 Göttingen

In the last years, the δ- phase of MnGa, which has a Curie temperature well above 300 K, gained great interest as a spin-injector for GaAs [1], achieving spin injection efficiencies of 5% at 2 K.

Recent results of MnGa growth on GaN [2] showed a nearly perfect epitaxial match between MnGa(111) and GaN(0001) layers exhibiting magnetic anisotropy along out-of-plane and in-plane directions.

We studied the MBE-growth of Mn_xGa_1−x on GaN(0001) templates with the aim of achieving spin injection through the MnGa/GaN interface, varying the Mn content x from 0.3 to 0.6. In order to obtain a smooth interface, different substrate temperatures and annealing methods have been investigated. The growth has been monitored in situ by RHEED. Magnetic and electrical transport properties have been measured in a temperature range from 2 to 400 K and magnetic fields up to 50 kOe. XRD and EDX measurements showed a strong dependence of these properties on stoichiometry and structure. Samples prepared in the van-der-Pauw and Hall-Bar geometry showed an anomalous hall effect, confirming spin polarized carrier transport in the MnGa layer. As a first step to characterize the electrical properties of the MnGa/GaN interface, Schottky diodes have been fabricated.

[1] Adelmann et al, APL 89 (2006),Nr. 11

[2] Lu et al, PRL 97 (2006)