Dynamic detection of electron spin accumulation in ferromagnet–semiconductor devices by ferromagnetic resonance

• Published in: Nature communications Vol. 7; no. 1; p. 10296
• Main Authors: Liu, Changjiang, Patel, Sahil J., Peterson, Timothy A., Geppert, Chad C., Christie, Kevin D., Stecklein, Gordon, Palmstrøm, Chris J., Crowell, Paul A.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 18-01-2016; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/119/1000; 639/301/119/1001; 639/301/119/2793; Electrons; Experiments; Humanities and Social Sciences; Lifetime; multidisciplinary; Science; Science (multidisciplinary); Temperature; United States > US; Santa Barbara California; California
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms10296

A distinguishing feature of spin accumulation in ferromagnet–semiconductor devices is its precession in a magnetic field. This is the basis for detection techniques such as the Hanle effect, but these approaches become ineffective as the spin lifetime in the semiconductor decreases. For this reason, no electrical Hanle measurement has been demonstrated in GaAs at room temperature. We show here that by forcing the magnetization in the ferromagnet to precess at resonance instead of relying only on the Larmor precession of the spin accumulation in the semiconductor, an electrically generated spin accumulation can be detected up to 300 K. The injection bias and temperature dependence of the measured spin signal agree with those obtained using traditional methods. We further show that this approach enables a measurement of short spin lifetimes (<100 ps), a regime that is not accessible in semiconductors using traditional Hanle techniques.
In semiconductor spintronic devices, Hanle precession allows for electrical detection of spin accumulation however it is inhibited at room temperature in GaAs by magnetic-field effects. Here, the authors present an alternative method for detecting spin accumulation based on ferromagnetic resonance.