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Negative resistance state in superconducting NbSe2 induced by surface acoustic waves
Masahiko Yokoi1, Satoshi Fujiwara1, Tomoya Kawamura1
1Department of Physics, Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan.
Science Advances
|September 16, 2020
Summary
We observed negative resistance in niobium diselenide (NbSe2) thin films when exposed to surface acoustic waves (SAWs). This phenomenon, where voltage opposes current, intensifies with higher SAW power and lower temperatures.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Superconductivity
Background:
- Superconductivity is a state of zero electrical resistance in certain materials below a critical temperature.
- Charge density waves (CDWs) are periodic modulations of electron density in some low-dimensional materials.
- Negative resistance is a condition where an increase in voltage leads to a decrease in current.
Purpose of the Study:
- To investigate the effect of surface acoustic waves (SAWs) on the superconducting properties of NbSe2 thin films.
- To explore the phenomenon of negative resistance in the superconducting state of NbSe2.
- To propose a mechanism for the observed negative resistance.
Main Methods:
- Fabrication of NbSe2 thin films.
- Irradiation of NbSe2 thin films with surface acoustic waves (SAWs).
- Measurement of electrical resistance under varying SAW power and temperature.
Main Results:
- Observation of negative resistance in the superconducting gap of NbSe2 thin films under SAW irradiation.
- The amplitude of negative resistance increases with increasing SAW power.
- The amplitude of negative resistance increases with decreasing temperature.
Conclusions:
- SAW-modulated soliton-antisoliton pairs in the CDW may act as a time-dependent capacitance, causing dc negative resistance.
- This finding offers a novel method for manipulating superconductivity under nonequilibrium conditions.
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