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Hall voltages without a magnetic field in a non-uniform two-dimensional electron system
Hwayong Noh1, Seung-Jo Lee, Seung Hyun Chun
1Department of Physics and Graphene Research Institute, Sejong University, Seoul 143-747, Korea. hnoh@sejong.ac.kr
Journal of Physics. Condensed Matter : an Institute of Physics Journal
|December 20, 2012
Summary
Researchers observed giant second-harmonic Hall voltages without a magnetic field in a 2D electron system. This novel spin Hall effect with in-plane spin polarization offers a new explanation for the observed phenomena.
Area of Science:
- Condensed matter physics
- Spintronics
- Semiconductor physics
Background:
- The Hall effect is a fundamental phenomenon in condensed matter physics, typically requiring a magnetic field.
- Second-harmonic Hall voltages are less common and their origins are not fully understood, especially in the absence of external magnetic fields.
Purpose of the Study:
- To investigate the origin of giant second-harmonic Hall voltages observed in a two-dimensional electron system with a transverse density gradient.
- To explore the characteristics of these voltages, including their dependence on electric field, temperature, and magnetic field.
- To propose a theoretical explanation for the observed phenomena.
Main Methods:
- Experimental measurement of Hall voltages in a two-dimensional electron system.
- Application of a transverse density gradient.
- Systematic variation of electric and magnetic fields.
- Temperature-dependent measurements.
Main Results:
- Observation of giant second-harmonic Hall voltages that persist without an external magnetic field.
- These voltages do not change sign upon current reversal.
- A quadratic dependence on the applied electric field was measured.
- Strong temperature dependence and significant magnetic field effects (magnitude and direction) were observed.
Conclusions:
- The observed behavior is consistent with a novel spin Hall effect.
- The proposed mechanism involves in-plane spin polarization.
- This finding opens new avenues for spintronic devices and understanding electron transport phenomena.
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