Crossover from Spin Accumulation into Interface States to Spin Injection in the Germanium Conduction Band

A. Jain (1) , C. Rojas-Sánchez (1) , M. Cubukcu (1) , J. Peiro (2) , J. C. Le Breton (2) , E. Prestat (3) , C. Vergnaud (1) , L. Louahadj (1) , C. Portemont (4) , C. Ducruet (4) , Vincent Baltz (5) , A. Barski (1) , Pascale Bayle-Guillemaud (3) , L. Vila (1) , J.-P. Attane (1) , E. Augendre (6) , G. Desfonds (7) , S. Gambarelli (7) , H. Jaffres (2) , J. M. George (2) , M. Jamet (1)

1 NM - Nanostructures et Magnétisme
2 Laboratoire Albert Fert (ex-UMPhy Unité mixte de physique CNRS/Thales)
3 LEMMA - Laboratoire d'Etude des Matériaux par Microscopie Avancée
4 CROCUS Technology
5 SPINTEC - SPINtronique et TEchnologie des Composants
6 CEA-LETI - Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information
7 RM - Magnetic Resonance

Electrical spin injection into semiconductors paves the way for exploring new phenomena in the area of spin physics and new generations of spintronic devices. However the exact role of interface states in the spin injection mechanism from a magnetic tunnel junction into a semiconductor is still under debate. In this Letter, we demonstrate a clear transition from spin accumulation into interface states to spin injection in the conduction band of n-Ge. We observe spin signal amplification at low temperature due to spin accumulation into interface states followed by a clear transition towards spin injection in the conduction band from 200 K up to room temperature. In this regime, the spin signal is reduced to a value compatible with the spin diffusion model. More interestingly, the observation in this regime of inverse spin Hall effect in germanium generated by spin pumping and the modulation of the spin signal by a gate voltage clearly demonstrate spin accumulation in the germanium conduction band.

Domaines: Matière Condensée [cond-mat]

A. Jain, C. Rojas-Sánchez, M. Cubukcu, J. Peiro, J. C. Le Breton, et al.. Crossover from Spin Accumulation into Interface States to Spin Injection in the Germanium Conduction Band. Physical Review Letters, 2012, 109, pp.106603. ⟨10.1103/PhysRevLett.109.106603⟩. ⟨hal-01683673⟩